Uma equipe formada por astrônomos de Israel, da Europa, da Coreia e dos EUA, anunciou a descoberta de um exoplaneta gigante gasoso circumbinário, na zona habitável de seu par de estrelas, uma ocorrência surpreendentemente comum para os exoplanetas circumbinários descobertos pela missão Kepler/K2 da NASA.
Lembrando o planeta da ficção, Tatooine, exoplanetas circumbinários orbitam duas estrelas e assim têm dois sóis em seu céu.
O exoplaneta circumbinário, recém-descoberto, denominado de Kepler-453b, leva 240.5 dias para orbitar suas estrelas, enquanto as estrelas orbitam uma com relação a outra a cada 27.3 dias.
A estrela maior, a Kepler-453A, é similar ao nosso Sol, contendo 94% da massa do Sol, enquanto que a estrela menor, a Kepler-453B, tem cerca de 20% da massa e é mais fria e mais apagada.
O sistema binário, localiza-se na constelação de Lyra, e está a aproximadamente 1400 anos-luz de distância da Terra. Estima-se que esse sistema tenha entre 1 e 2 bilhões de anos de vida, sendo bem mais novo que o nosso Sistema Solar.
Também conhecido como KIC 9632895b, o Kepler-453b tem um raio 6.2 vezes maior que o da Terra. Sua massa não foi medida nos dados atuais, mas provavelmente ele deve ter cerca de 16 vezes a massa da Terra.
De acordo com os astrônomos, o Kepler-453b, é o terceiro planeta circumbinário da missão Kepler, descoberto na zona habitável de um par de estrelas.
Devido ao seu tamanho, e a sua natureza gasosa, o planeta pouco provavelmente deve abrigar a vida como nós a conhecemos. Contudo, ele pode, como os gigantes gasosos do Sistema Solar, ter grandes luas, e essas luas poderiam ser habitáveis. Sua órbita se manterá estável por 10 milhões de anos, aumentando a possibilidade da vida se formar nas suas luas.
Com o número de exoplanetas circumbinários conhecidos agora em dez, os cientistas podem começar a comparar diferentes sistemas e procurar uma tendência. Os sistemas tendem a ser bem compactos e podem aparecer num grande número de configurações.
Uma vez pensados como sendo raros e até mesmo impossíveis de existir, essa e outras descobertas do Kepler, confirmam que esses planetas são comuns na nossa Via Láctea.
“A diversidade e complexidade desses sistemas circumbinários é algo maravilhoso. Cada novo planeta circumbinário, é uma joia, revelando algo inesperado e desafiador”, disse o Prof. William Welsh da Universidade Estadual de San Diego, e o primeiro autor do artigo que descreve a descoberta, publicado no Astrophysical Journal.
Fonte:
http://www.sci-news.com/astronomy/science-kepler453b-circumbinary-exoplanet-03117.html
This document summarizes the discovery of a transiting circumbinary planet (PH1) in a quadruple star system by volunteers with the Planet Hunters citizen science project. PH1 orbits outside a 20-day eclipsing binary consisting of an F dwarf and an M dwarf star. It has a radius of 6.18 ± 0.17 R⊕ and an upper mass limit of 169 M⊕. Beyond PH1's orbit is a distant visual binary bound to the system, making this the first known case of a transiting planet in a quadruple star configuration. Planet Hunters volunteers identified transit features in the Kepler light curve of KIC 4862625 through visual inspection and discussion, leading to the confirmation and characterization
This document summarizes the discovery of two new circumbinary planets, Kepler-34b and Kepler-35b, found using data from the Kepler spacecraft. Kepler-34b orbits two sun-like stars every 289 days, while Kepler-35b orbits a pair of smaller stars every 131 days. Both planets are gas giants that experience large variations in stellar radiation from the orbital motion of their parent stars. Analysis of Kepler photometry and spectroscopic data determined the orbital and physical parameters of the planets and their host star systems. The discovery of these planets implies that over 1% of close binary star systems have giant planets in aligned orbits, representing millions of planets in the Milky Way galaxy.
1) The document reports the discovery of two new circumbinary planets, Kepler-34b and Kepler-35b, orbiting binary star systems.
2) Kepler-34b orbits two sun-like stars every 289 days, while Kepler-35b orbits a pair of smaller stars every 131 days.
3) Analysis of photometric and spectroscopic data confirms the planetary nature of the transiting bodies and determines system parameters like the planets' masses and radii.
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2Sérgio Sacani
This document reports the discovery of three transiting super-Earth planets orbiting a nearby bright M0 dwarf star, EPIC 201367065, using data from the K2 mission. Photometry from K2 reveals three planetary candidates with orbital periods of 10.056, 24.641, and ~45 days and radii between 1.5-2.1 Earth radii. Spectroscopy of the host star determines it has a mass of 0.601 solar masses, radius of 0.561 solar radii, and is located about 45 parsecs away, making the planets some of the coolest small planets known around a nearby star. The system presents an opportunity to measure the planet masses and constrain atmospheric compositions via future observations
Evidence for reflected_lightfrom_the_most_eccentric_exoplanet_knownSérgio Sacani
Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from AAT and PARAS observations during periastron passage greatly improve our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is > 1.22◦, ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using MOST rule out a transit of the planet and reveal evidence of phase variations during periastron. These possible photometric phase variations may be caused by reflected light from the planet’s atmosphere and the dramatic change in star–planet separation surrounding the periastron passage.
TEMPORAL EVOLUTION OF THE HIGH-ENERGY IRRADIATION AND WATER CONTENT OF TRAPPI...Sérgio Sacani
The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could
harbour liquid water on their surfaces. UV observations are essential to measure their high-energy
irradiation, and to search for photodissociated water escaping from their putative atmospheres. Our
new observations of TRAPPIST-1 Ly-α line during the transit of TRAPPIST-1c show an evolution of
the star emission over three months, preventing us from assessing the presence of an extended hydrogen
exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history
of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the
orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape.
However, TRAPPIST-1e to h might have lost less than 3 Earth oceans if hydrodynamic escape stopped
once they entered the habitable zone. We caution that these estimates remain limited by the large
uncertainty on the planet masses. They likely represent upper limits on the actual water loss because
our assumptions maximize the XUV-driven escape, while photodissociation in the upper atmospheres
should be the limiting process. Late-stage outgassing could also have contributed significant amounts
of water for the outer, more massive planets after they entered the habitable zone. While our results
suggest that the outer planets are the best candidates to search for water with the JWST, they also
highlight the need for theoretical studies and complementary observations in all wavelength domains
to determine the nature of the TRAPPIST-1 planets, and their potential habitability.
Keywords: planetary systems - Stars: individual: TRAPPIST-1
DISCOVERY OF A GALAXY CLUSTER WITH A VIOLENTLY STARBURSTING CORE AT z = 2:506Sérgio Sacani
We report the discovery of a remarkable concentration of massive galaxies with extended X-ray
emission at zspec = 2:506, which contains 11 massive (M & 1011M) galaxies in the central 80kpc
region (11.6 overdensity). We have spectroscopically conrmed 17 member galaxies with 11 from CO
and the remaining ones from H. The X-ray luminosity, stellar mass content and velocity dispersion
all point to a collapsed, cluster-sized dark matter halo with mass M200c = 1013:90:2M, making it
the most distant X-ray-detected cluster known to date. Unlike other clusters discovered so far, this
structure is dominated by star-forming galaxies (SFGs) in the core with only 2 out of the 11 massive
galaxies classied as quiescent. The star formation rate (SFR) in the 80kpc core reaches 3400 M
yr 1 with a gas depletion time of 200 Myr, suggesting that we caught this cluster in rapid build-up
of a dense core. The high SFR is driven by both a high abundance of SFGs and a higher starburst
fraction ( 25%, compared to 3%-5% in the eld). The presence of both a collapsed, cluster-sized
halo and a predominant population of massive SFGs suggests that this structure could represent an
important transition phase between protoclusters and mature clusters. It provides evidence that the
main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster,
providing new insights into massive cluster formation at early epochs. The large integrated stellar
mass at such high redshift challenges our understanding of massive cluster formation.
This document summarizes the discovery of a transiting circumbinary planet (PH1) in a quadruple star system by volunteers with the Planet Hunters citizen science project. PH1 orbits outside a 20-day eclipsing binary consisting of an F dwarf and an M dwarf star. It has a radius of 6.18 ± 0.17 R⊕ and an upper mass limit of 169 M⊕. Beyond PH1's orbit is a distant visual binary bound to the system, making this the first known case of a transiting planet in a quadruple star configuration. Planet Hunters volunteers identified transit features in the Kepler light curve of KIC 4862625 through visual inspection and discussion, leading to the confirmation and characterization
This document summarizes the discovery of two new circumbinary planets, Kepler-34b and Kepler-35b, found using data from the Kepler spacecraft. Kepler-34b orbits two sun-like stars every 289 days, while Kepler-35b orbits a pair of smaller stars every 131 days. Both planets are gas giants that experience large variations in stellar radiation from the orbital motion of their parent stars. Analysis of Kepler photometry and spectroscopic data determined the orbital and physical parameters of the planets and their host star systems. The discovery of these planets implies that over 1% of close binary star systems have giant planets in aligned orbits, representing millions of planets in the Milky Way galaxy.
1) The document reports the discovery of two new circumbinary planets, Kepler-34b and Kepler-35b, orbiting binary star systems.
2) Kepler-34b orbits two sun-like stars every 289 days, while Kepler-35b orbits a pair of smaller stars every 131 days.
3) Analysis of photometric and spectroscopic data confirms the planetary nature of the transiting bodies and determines system parameters like the planets' masses and radii.
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2Sérgio Sacani
This document reports the discovery of three transiting super-Earth planets orbiting a nearby bright M0 dwarf star, EPIC 201367065, using data from the K2 mission. Photometry from K2 reveals three planetary candidates with orbital periods of 10.056, 24.641, and ~45 days and radii between 1.5-2.1 Earth radii. Spectroscopy of the host star determines it has a mass of 0.601 solar masses, radius of 0.561 solar radii, and is located about 45 parsecs away, making the planets some of the coolest small planets known around a nearby star. The system presents an opportunity to measure the planet masses and constrain atmospheric compositions via future observations
Evidence for reflected_lightfrom_the_most_eccentric_exoplanet_knownSérgio Sacani
Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from AAT and PARAS observations during periastron passage greatly improve our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is > 1.22◦, ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using MOST rule out a transit of the planet and reveal evidence of phase variations during periastron. These possible photometric phase variations may be caused by reflected light from the planet’s atmosphere and the dramatic change in star–planet separation surrounding the periastron passage.
TEMPORAL EVOLUTION OF THE HIGH-ENERGY IRRADIATION AND WATER CONTENT OF TRAPPI...Sérgio Sacani
The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could
harbour liquid water on their surfaces. UV observations are essential to measure their high-energy
irradiation, and to search for photodissociated water escaping from their putative atmospheres. Our
new observations of TRAPPIST-1 Ly-α line during the transit of TRAPPIST-1c show an evolution of
the star emission over three months, preventing us from assessing the presence of an extended hydrogen
exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history
of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the
orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape.
However, TRAPPIST-1e to h might have lost less than 3 Earth oceans if hydrodynamic escape stopped
once they entered the habitable zone. We caution that these estimates remain limited by the large
uncertainty on the planet masses. They likely represent upper limits on the actual water loss because
our assumptions maximize the XUV-driven escape, while photodissociation in the upper atmospheres
should be the limiting process. Late-stage outgassing could also have contributed significant amounts
of water for the outer, more massive planets after they entered the habitable zone. While our results
suggest that the outer planets are the best candidates to search for water with the JWST, they also
highlight the need for theoretical studies and complementary observations in all wavelength domains
to determine the nature of the TRAPPIST-1 planets, and their potential habitability.
Keywords: planetary systems - Stars: individual: TRAPPIST-1
DISCOVERY OF A GALAXY CLUSTER WITH A VIOLENTLY STARBURSTING CORE AT z = 2:506Sérgio Sacani
We report the discovery of a remarkable concentration of massive galaxies with extended X-ray
emission at zspec = 2:506, which contains 11 massive (M & 1011M) galaxies in the central 80kpc
region (11.6 overdensity). We have spectroscopically conrmed 17 member galaxies with 11 from CO
and the remaining ones from H. The X-ray luminosity, stellar mass content and velocity dispersion
all point to a collapsed, cluster-sized dark matter halo with mass M200c = 1013:90:2M, making it
the most distant X-ray-detected cluster known to date. Unlike other clusters discovered so far, this
structure is dominated by star-forming galaxies (SFGs) in the core with only 2 out of the 11 massive
galaxies classied as quiescent. The star formation rate (SFR) in the 80kpc core reaches 3400 M
yr 1 with a gas depletion time of 200 Myr, suggesting that we caught this cluster in rapid build-up
of a dense core. The high SFR is driven by both a high abundance of SFGs and a higher starburst
fraction ( 25%, compared to 3%-5% in the eld). The presence of both a collapsed, cluster-sized
halo and a predominant population of massive SFGs suggests that this structure could represent an
important transition phase between protoclusters and mature clusters. It provides evidence that the
main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster,
providing new insights into massive cluster formation at early epochs. The large integrated stellar
mass at such high redshift challenges our understanding of massive cluster formation.
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With...Sérgio Sacani
We are conducting a survey for distant solar system objects beyond the Kuiper
Belt edge ( 50 AU) with new wide-field cameras on the Subaru and CTIO tele-
scopes. We are interested in the orbits of objects that are decoupled from the
giant planet region in order to understand the structure of the outer solar sys-
tem, including whether a massive planet exists beyond a few hundred AU as first
reported in Trujillo and Sheppard (2014). In addition to discovering extreme
trans-Neptunian objects detailed elsewhere, we have found several objects with
high perihelia (q > 40 AU) that differ from the extreme and inner Oort cloud
objects due to their moderate semi-major axes (50 < a < 100 AU) and eccen-
tricities (e . 0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345 have
the third and fourth highest perihelia known after Sedna and 2012 VP113, yet
their orbits are not nearly as eccentric or distant. We found several of these high
perihelion but moderate orbit objects and observe that they are mostly near Nep-
tune mean motion resonances and have significant inclinations (i > 20 degrees).
These moderate objects likely obtained their unusual orbits through combined
interactions with Neptune’s mean motion resonances and the Kozai resonance,
similar to the origin scenarios for 2004 XR190. We also find the distant 2008
ST291 has likely been modified by the MMR+KR mechanism through the 6:1
Neptune resonance. We discuss these moderately eccentric, distant objects along
with some other interesting low inclination outer classical belt objects like 2012
FH84 discovered in our ongoing survey.
WHERE IS THE FLUX GOING? THE LONG-TERM PHOTOMETRIC VARIABILITY OF BOYAJIAN’S ...Sérgio Sacani
We present ∼ 800 days of photometric monitoring of Boyajian’s Star (KIC 8462852) from the AllSky
Automated Survey for Supernovae (ASAS-SN) and ∼ 4000 days of monitoring from the All Sky
Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian’s Star
has steadily decreased at a rate of 6.3 ± 1.4 mmag yr−1
, such that the star is now 1.5% fainter than it
was in February 2015. Moreover, the longer time baseline afforded by ASAS suggests that Boyajian’s
Star has also undergone two brightening episodes in the past 11 years, rather than only exhibiting a
monotonic decline. We analyze a sample of ∼ 1000 comparison stars of similar brightness located in
the same ASAS-SN field and demonstrate that the recent fading is significant at & 99.4% confidence.
The 2015 − 2017 dimming rate is consistent with that measured with Kepler data for the time period
from 2009 to 2013. This long-term variability is difficult to explain with any of the physical models
for the star’s behavior proposed to date
Four new planets_around_giant_stars_and_the_mass_metallicity_correlation_of_p...Sérgio Sacani
Exoplanet searches have revealed interesting correlations between the stellar properties and the occurrence rate of planets.
In particular, different independent surveys have demonstrated that giant planets are preferentially found around metal-rich stars and
that their fraction increases with the stellar mass.
Aims. During the past six years, we have conducted a radial velocity follow-up program of 166 giant stars, to detect substellar
companions, and characterizing their orbital properties. Using this information, we aim to study the role of the stellar evolution in
the orbital parameters of the companions, and to unveil possible correlations between the stellar properties and the occurrence rate of
giant planets.
Methods. We have taken multi-epoch spectra using FEROS and CHIRON for all of our targets, from which we have computed
precision radial velocities and we have derived atmospheric and physical parameters. Additionally, velocities computed from UCLES
spectra are presented here. By studying the periodic radial velocity signals, we have detected the presence of several substellar
companions.
Results. We present four new planetary systems around the giant stars HIP8541, HIP74890, HIP84056 and HIP95124. Additionally,
we study the correlation between the occurrence rate of giant planets with the stellar mass and metallicity of our targets. We find that
giant planets are more frequent around metal-rich stars, reaching a peak in the detection of f = 16.7+15.5
−5.9 % around stars with [Fe/H] ∼
0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M⋆∼ 1.0 - 2.1 M⊙ ,
with a maximum of f = 13.0+10.1
−4.2 %, at M⋆= 2.1 M⊙ .
Conclusions. We conclude that giant planets are preferentially formed around metal-rich stars. Also, we conclude that they are more
efficiently formed around more massive stars, in the stellar mass range of ∼ 1.0 - 2.1 M⊙ . These observational results confirm previous
findings for solar-type and post-MS hosting stars, and provide further support to the core-accretion formation model.
Probing the innermost_regions_of_agn_jets_and_their_magnetic_fields_with_radi...Sérgio Sacani
Desde 1974, observações feitas com o chamado Long Baseline Interferometry, ou VLBI, combinaram sinais de um objeto cósmico recebidos em diferentes rádio telescópios espalhados pelo globo para criar uma antena com o tamanho equivalente à maior separação entre elas. Isso fez com que fosse possível fazer imagens com uma nitidez sem precedentes, com uma resolução 1000 vezes melhor do que Hubble consegue na luz visível. Agora, uma equipe internacional de astrônomos quebrou todos os recordes combinando 15 rádio telescópios na Terra e a antena de rádio da missão RadioAstron, da agência espacial russa, na órbita da Terra. O trabalho, liderado pelo Instituto de Astrofísica de Andalucía, o IAA-CSIC, forneceu novas ideias sobre a natureza das galáxias ativas, onde um buraco negro extremamente massivo engole a matéria ao redor enquanto simultaneamente emite um par de jatos de partículas de alta energia e campos magnéticos a velocidades próximas da velocidade da luz.
Observações feitas no comprimento de onda das micro-ondas são essenciais para explorar esses jatos, já que os elétrons de alta energia se movendo em campos magnéticos são mais proficientes em produzir micro-ondas. Mas a maioria das galáxias ativas com jatos brilhantes estão a bilhões de anos-luz de distância da Terra, de modo que esses jatos são minúsculos no céu. Desse modo a alta resolução é essencial para observar esses jatos em ação e então revelar fenômenos como as ondas de choque e a turbulência que controla o quanto de luz é produzida num dado tempo. “Combinando pela primeira vez rádio telescópios na Terra com rádio telescópios no espaço, operando na máxima resolução, tem permitido que a nossa equipe crie uma antena que tem um tamanho equivalente a 8 vezes o diâmetro da Terra, correspondendo a 20 micro arcos de segundo”, disse José L; Gómez, o líder da equipe no Instituto de Astrofísica de Andalucía, IAA-CSIC.
Proper-motion age dating of the progeny of Nova Scorpii ad 1437Sérgio Sacani
‘Cataclysmic variables’ are binary star systems in which one
star of the pair is a white dwarf, and which often generate bright
and energetic stellar outbursts. Classical novae are one type of
outburst: when the white dwarf accretes enough matter from its
companion, the resulting hydrogen-rich atmospheric envelope
can host a runaway thermonuclear reaction that generates a rapid
brightening1–4. Achieving peak luminosities of up to one million
times that of the Sun5
, all classical novae are recurrent, on timescales
of months6
to millennia7
. During the century before and after an
eruption, the ‘novalike’ binary systems that give rise to classical
novae exhibit high rates of mass transfer to their white dwarfs8
.
Another type of outburst is the dwarf nova: these occur in binaries
that have stellar masses and periods indistinguishable from those
of novalikes9
but much lower mass-transfer rates10, when accretiondisk
instabilities11 drop matter onto the white dwarfs. The coexistence
at the same orbital period of novalike binaries and dwarf
novae—which are identical but for their widely varying accretion
rates—has been a longstanding puzzle9
. Here we report the recovery
of the binary star underlying the classical nova eruption of 11 March
ad 1437 (refs 12, 13), and independently confirm its age by propermotion
dating. We show that, almost 500 years after a classical-nova
event, the system exhibited dwarf-nova eruptions. The three other
oldest recovered classical novae14–16 display nova shells, but lack
firm post-eruption ages17,18, and are also dwarf novae at present.
We conclude that many old novae become dwarf novae for part of
the millennia between successive nova eruptions19,
A nearby yoiung_m_dwarf_with_wide_possibly_planetary_m_ass_companionSérgio Sacani
This document summarizes the identification of two young objects, TYC 9486-927-1 and 2MASS J21265040−8140293, as a likely very wide binary system. It presents revised astrometry showing they have common proper motion. Spectroscopy of the secondary yields a radial velocity consistent with the primary. Analysis of lithium absorption and kinematics suggests an age range of 10-45 Myr, with the secondary having an estimated mass in the planetary mass regime. If confirmed, this would be the widest known exoplanet system at over 4500 AU separation.
A super earth_sized_planet_orbiting_in_or_near_the_habitable_zone_around_sun_...Sérgio Sacani
This document summarizes the discovery of a super-Earth-sized planet orbiting in or near the habitable zone of a Sun-like star called Kepler-69. Using data from the Kepler spacecraft, astronomers detected two planets transiting Kepler-69, called Kepler-69b and Kepler-69c. Kepler-69c is estimated to have a radius of 1.7 Earth radii and orbit every 242.5 days, placing it close to the star's habitable zone where liquid water could exist on the surface. At 1.7 Earth radii, Kepler-69c represents the smallest planet found by Kepler to be potentially habitable, and is an important discovery on the path to finding the first true Earth analog.
Evidence for a_distant_giant_planet_in_the_solar_systemSérgio Sacani
A descoberta de um novo planeta, atualmente não é uma manchete que chama tanto assim a atenção das pessoas. Muito disso, graças ao Telescópio Espacial Kepler, que já descobriu quase 2000 exoplanetas e todo instante uma nova descoberta é anunciada, certo? Mais ou menos, a descoberta anunciada hoje, dia 20 de Janeiro de 2016, é um pouco diferente, pois não se trata de um exoplaneta, e sim de um novo planeta no Sistema Solar, e esse é um fato que intriga os astrônomos a muitos e muitos anos.
Porém, temos que ir com calma com esses anúncios. No artigo aceito para publicação no The Astronomical Journal (artigo no final do post), os autores, Mike Brown e Konstantin Batygin, do Instituto de Tecnologia da Califórnia, apresentaram o que eles dizem ser evidências circunstâncias fortes para a existência de um grande planeta ainda não descoberto, talvez, com uma massa 10 vezes a massa da Terra, orbitando os confins do nosso Sistema Solar, muito além da órbita de Plutão. Os cientistas inferiram sua presença, por meio de anomalias encontradas nas órbitas de seis objetos do chamado Cinturão de Kuiper.
O objeto, que os pesquisadores estão chamando de Planeta Nove, não chega muito perto do Sol, no ponto mais próximo da sua órbita ele fica a 30.5 bilhões de quilômetros, ou seja, cinco vezes a distância entre o Sol e Plutão. Apesar do seu grande tamanho, ele é muito apagado, e por isso ninguém até o momento conseguiu observá-lo.
Não existe ainda uma confirmação observacional da descoberta, mas as evidências são tão fortes que fizeram com que outros especialistas como Chad Trujilo do Observatório Gemini no Havaí e David Nesvorny, do Southwest Research Institute em Boulder no Colorado, ficassem impressionados e bem convencidos de que deve mesmo haver um grande planeta nas fronteiras da nossa vizinhança cósmica.
Kepler-1647b is the largest and longest-period Kepler transiting circumbinary planet discovered to date. It orbits an eclipsing binary star system with an orbital period of approximately 1100 days, making it one of the longest-period transiting planets known. The planet is around 1.06 times the size of Jupiter and perturbes the times of the stellar eclipses, allowing its mass to be measured at 1.52 times that of Jupiter. Despite its long orbital period compared to Earth, the planet resides in the habitable zone of the binary star system throughout its orbit. The discovery of this unusual planetary system provides insights into theories of planet formation and dynamics in multiple star systems.
EXTINCTION AND THE DIMMING OF KIC 8462852Sérgio Sacani
To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star
over a wide wavelength range from the UV to the mid-infrared from October 2015 through December
2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm
fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period
reported is 22.1 ± 9.7 milli-mag yr−1
in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in
the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2
mmag yr−1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at
& 3 σ by three different observatories operating from the UV to the IR. The presence of long-term
secular dimming means that previous SED models of the star based on photometric measurements
taken years apart may not be accurate. We find that stellar models with Tef f = 7000 - 7100 K and
AV ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the
near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from
a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of
the fading favors a relatively neutral color (i.e., RV & 5, but not flat across all the bands) compared
with the extinction law for the general ISM (RV = 3.1), suggesting that the dimming arises from
circumstellar material
The identification of_93_day_periodic_photometric_variability_for_yso_ylw_16aSérgio Sacani
This study identifies a 93 day periodic photometric variability in the Class I young stellar object (YSO) YLW 16A in the Rho Ophiuchus star forming region. Light curve analysis reveals variations of ~0.5 magnitudes in the Ks band over this period. The authors propose a triple system model consisting of an inner binary with a 93 day period eclipsed by a warped circumbinary disk, with a tertiary companion at ~40 AU responsible for warping the disk. This model is similar to one previously proposed for another YSO, WL 4, and may indicate such triple systems with eclipsing disks are common around young stars. Understanding these systems can provide insights into stellar and planetary formation and evolution.
Bright features have been recently discovered by Dawn on Ceres, which extend
previous photometric and Space Telescope observations. These features should produce
distortions of the line profiles of the reflected solar spectrum and therefore an apparent
radial velocity variation modulated by the rotation of the dwarf planet. Here we report
on two sequences of observations of Ceres performed in the nights of 31 July, 26-
27 August 2015 by means of the high-precision HARPS spectrograph at the 3.6-m
La Silla ESO telescope. The observations revealed a quite complex behaviour which
likely combines a radial velocity modulation due to the rotation with an amplitude of
⇡ ±6 m s
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
Is there an_exoplanet_in_the_solar_systemSérgio Sacani
We investigate the prospects for the capture of the proposed Planet 9 from other
stars in the Sun’s birth cluster. Any capture scenario must satisfy three conditions:
the encounter must be more distant than ∼ 150 au to avoid perturbing the Kuiper
belt; the other star must have a wide-orbit planet (a & 100 au); the planet must be
captured onto an appropriate orbit to sculpt the orbital distribution of wide-orbit
Solar System bodies. Here we use N-body simulations to show that these criteria may
be simultaneously satisfied. In a few percent of slow close encounters in a cluster,
bodies are captured onto heliocentric, Planet 9-like orbits. During the ∼ 100 Myr
cluster phase, many stars are likely to host planets on highly-eccentric orbits with
apastron distances beyond 100 au if Neptune-sized planets are common and susceptible
to planet–planet scattering. While the existence of Planet 9 remains unproven, we
consider capture from one of the Sun’s young brethren a plausible route to explain such
an object’s orbit. Capture appears to predict a large population of Trans-Neptunian
Objects (TNOs) whose orbits are aligned with the captured planet, and we propose
that different formation mechanisms will be distinguishable based on their imprint on
the distribution of TNOs
An earth sized_planet_with_an_earth_sized_densitySérgio Sacani
1) Researchers observed the exoplanet Kepler-78b using the HARPS-N spectrograph to measure its mass.
2) They measured Kepler-78b's mass to be 1.86 Earth masses, giving it a density similar to Earth, implying a rocky composition of iron and rock.
3) The small size of Kepler-78b makes it the smallest exoplanet yet measured for both mass and radius, establishing that Earth-sized planets can be terrestrial.
The transit method detects exoplanets by observing periodic dips in a star's light caused by planets passing in front of the star. This method has discovered over 80% of known exoplanets. It allows determining planet properties like radius, atmosphere composition by analyzing light passing through. The Kepler space telescope extensively uses this method to study exoplanet candidates.
The kepler 10_planetary_system_revisited_by_harpsSérgio Sacani
This document discusses observations of the Kepler-10 planetary system made with the HARPS-N spectrograph. The observations resulted in improved precision for the masses of Kepler-10b and Kepler-10c. Kepler-10b's mass was determined to be 3.33 ± 0.49 Earth masses, confirming its rocky composition. Kepler-10c's mass of 17.2 ± 1.9 Earth masses makes it the first strong evidence of a class of more massive solid Neptune-sized planets with longer orbital periods. The improved mass measurements will help constrain models of the internal structure and composition of these planets.
Chiotelis Ioannis, Theodoropoulou Maria, “Searching for Black Holes. Photometry in our Classrooms”, Hellenic Conference on Innovating STEM Education, 16-18 December 2016, Athens, Greece.
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument StudySérgio Sacani
On 19 Feb. 2016 nine Rosetta instruments serendipitously observed an outburst of gas and dust
from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras
and spectrometers ranging from UV over visible to microwave wavelengths, in-situ gas, dust and
plasma instruments, and one dust collector. At 9:40 a dust cloud developed at the edge of an image
in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature
of the outburst that signicantly exceeded the background. The enhancement ranged from 50% of
the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus.
Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest
enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3
and consequently the spacecraft potential changed from 16V to 20V during the outburst. A
clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15
minutes the Star Tracker camera detected fast particles ( 25 ms 1) while 100 m radius particles
were detected by the GIADA dust instrument 1 hour later at a speed of 6 ms 1. The slowest
were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst
originated just outside the FOV of the instruments, the source region and the magnitude of the
outburst could be determined.
The completeness-corrected rate of stellar encounters with the Sun from the f...Sérgio Sacani
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial
velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which
come within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the
Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a
similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars
with large radial velocity uncertainties (>10 km s−1
), and partly because of missing stars in GDR1 (especially at the bright end). The
closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict
a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000–21 000 AU), which will
bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together
with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function
of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars
with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be
545±59 Myr−1
. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds
to 87 ± 9 Myr−1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
A giant ring_like_structure_at_078_z_086_displayed_by_gr_bsSérgio Sacani
This document describes the discovery of a giant ring-like structure in the observable universe displayed by 9 gamma ray bursts (GRBs) between redshifts of 0.78 and 0.86. The ring has a diameter of 1720 Mpc, over five times larger than the expected transition scale to homogeneity. The ring lies at a distance of 2770 Mpc with major and minor diameters of 43° and 30°, respectively. The probability of this structure occurring by random chance is calculated to be 2 × 10-6. This ring-shaped feature contradicts the cosmological principle of large-scale homogeneity and isotropy, and the physical mechanism responsible is unknown.
Confirmation of the_ogle_planet_signature_and_its_characteristics_with_lens_s...Sérgio Sacani
O Telescópio Espacial Hubble e o Observatório W. M. Keck, no Havaí, fizeram confirmações independentes de um exoplaneta orbitando sua estrela central de uma distância bem grande. O planeta foi descoberto através de uma técnica chamada de microlente gravitacional.
Essa descoberta traz uma nova peça para o processo de caçada de exoplanetas: para descobrir planetas longe de suas estrelas, como Júpiter e Saturno estão do Sol. Os resultados obtidos pelo Hubble e pelo Keck apareceram em dois artigos da edição de 30 de Julho de 2015 do The Astrophysical Journal.
A grande maioria dos exoplanetas catalogados são aqueles localizados bem perto de suas estrelas, isso acontece porque as técnicas atuais de se caçar exoplanetas favorecem a descoberta de planetas com curtos períodos orbitais. Mas esse não é o caso da técnica de microlente gravitacional, que pode encontrar planetas mais frios e mais distantes com órbitas de longo período que outros métodos não são capazes de detectar.
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With...Sérgio Sacani
We are conducting a survey for distant solar system objects beyond the Kuiper
Belt edge ( 50 AU) with new wide-field cameras on the Subaru and CTIO tele-
scopes. We are interested in the orbits of objects that are decoupled from the
giant planet region in order to understand the structure of the outer solar sys-
tem, including whether a massive planet exists beyond a few hundred AU as first
reported in Trujillo and Sheppard (2014). In addition to discovering extreme
trans-Neptunian objects detailed elsewhere, we have found several objects with
high perihelia (q > 40 AU) that differ from the extreme and inner Oort cloud
objects due to their moderate semi-major axes (50 < a < 100 AU) and eccen-
tricities (e . 0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345 have
the third and fourth highest perihelia known after Sedna and 2012 VP113, yet
their orbits are not nearly as eccentric or distant. We found several of these high
perihelion but moderate orbit objects and observe that they are mostly near Nep-
tune mean motion resonances and have significant inclinations (i > 20 degrees).
These moderate objects likely obtained their unusual orbits through combined
interactions with Neptune’s mean motion resonances and the Kozai resonance,
similar to the origin scenarios for 2004 XR190. We also find the distant 2008
ST291 has likely been modified by the MMR+KR mechanism through the 6:1
Neptune resonance. We discuss these moderately eccentric, distant objects along
with some other interesting low inclination outer classical belt objects like 2012
FH84 discovered in our ongoing survey.
WHERE IS THE FLUX GOING? THE LONG-TERM PHOTOMETRIC VARIABILITY OF BOYAJIAN’S ...Sérgio Sacani
We present ∼ 800 days of photometric monitoring of Boyajian’s Star (KIC 8462852) from the AllSky
Automated Survey for Supernovae (ASAS-SN) and ∼ 4000 days of monitoring from the All Sky
Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian’s Star
has steadily decreased at a rate of 6.3 ± 1.4 mmag yr−1
, such that the star is now 1.5% fainter than it
was in February 2015. Moreover, the longer time baseline afforded by ASAS suggests that Boyajian’s
Star has also undergone two brightening episodes in the past 11 years, rather than only exhibiting a
monotonic decline. We analyze a sample of ∼ 1000 comparison stars of similar brightness located in
the same ASAS-SN field and demonstrate that the recent fading is significant at & 99.4% confidence.
The 2015 − 2017 dimming rate is consistent with that measured with Kepler data for the time period
from 2009 to 2013. This long-term variability is difficult to explain with any of the physical models
for the star’s behavior proposed to date
Four new planets_around_giant_stars_and_the_mass_metallicity_correlation_of_p...Sérgio Sacani
Exoplanet searches have revealed interesting correlations between the stellar properties and the occurrence rate of planets.
In particular, different independent surveys have demonstrated that giant planets are preferentially found around metal-rich stars and
that their fraction increases with the stellar mass.
Aims. During the past six years, we have conducted a radial velocity follow-up program of 166 giant stars, to detect substellar
companions, and characterizing their orbital properties. Using this information, we aim to study the role of the stellar evolution in
the orbital parameters of the companions, and to unveil possible correlations between the stellar properties and the occurrence rate of
giant planets.
Methods. We have taken multi-epoch spectra using FEROS and CHIRON for all of our targets, from which we have computed
precision radial velocities and we have derived atmospheric and physical parameters. Additionally, velocities computed from UCLES
spectra are presented here. By studying the periodic radial velocity signals, we have detected the presence of several substellar
companions.
Results. We present four new planetary systems around the giant stars HIP8541, HIP74890, HIP84056 and HIP95124. Additionally,
we study the correlation between the occurrence rate of giant planets with the stellar mass and metallicity of our targets. We find that
giant planets are more frequent around metal-rich stars, reaching a peak in the detection of f = 16.7+15.5
−5.9 % around stars with [Fe/H] ∼
0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M⋆∼ 1.0 - 2.1 M⊙ ,
with a maximum of f = 13.0+10.1
−4.2 %, at M⋆= 2.1 M⊙ .
Conclusions. We conclude that giant planets are preferentially formed around metal-rich stars. Also, we conclude that they are more
efficiently formed around more massive stars, in the stellar mass range of ∼ 1.0 - 2.1 M⊙ . These observational results confirm previous
findings for solar-type and post-MS hosting stars, and provide further support to the core-accretion formation model.
Probing the innermost_regions_of_agn_jets_and_their_magnetic_fields_with_radi...Sérgio Sacani
Desde 1974, observações feitas com o chamado Long Baseline Interferometry, ou VLBI, combinaram sinais de um objeto cósmico recebidos em diferentes rádio telescópios espalhados pelo globo para criar uma antena com o tamanho equivalente à maior separação entre elas. Isso fez com que fosse possível fazer imagens com uma nitidez sem precedentes, com uma resolução 1000 vezes melhor do que Hubble consegue na luz visível. Agora, uma equipe internacional de astrônomos quebrou todos os recordes combinando 15 rádio telescópios na Terra e a antena de rádio da missão RadioAstron, da agência espacial russa, na órbita da Terra. O trabalho, liderado pelo Instituto de Astrofísica de Andalucía, o IAA-CSIC, forneceu novas ideias sobre a natureza das galáxias ativas, onde um buraco negro extremamente massivo engole a matéria ao redor enquanto simultaneamente emite um par de jatos de partículas de alta energia e campos magnéticos a velocidades próximas da velocidade da luz.
Observações feitas no comprimento de onda das micro-ondas são essenciais para explorar esses jatos, já que os elétrons de alta energia se movendo em campos magnéticos são mais proficientes em produzir micro-ondas. Mas a maioria das galáxias ativas com jatos brilhantes estão a bilhões de anos-luz de distância da Terra, de modo que esses jatos são minúsculos no céu. Desse modo a alta resolução é essencial para observar esses jatos em ação e então revelar fenômenos como as ondas de choque e a turbulência que controla o quanto de luz é produzida num dado tempo. “Combinando pela primeira vez rádio telescópios na Terra com rádio telescópios no espaço, operando na máxima resolução, tem permitido que a nossa equipe crie uma antena que tem um tamanho equivalente a 8 vezes o diâmetro da Terra, correspondendo a 20 micro arcos de segundo”, disse José L; Gómez, o líder da equipe no Instituto de Astrofísica de Andalucía, IAA-CSIC.
Proper-motion age dating of the progeny of Nova Scorpii ad 1437Sérgio Sacani
‘Cataclysmic variables’ are binary star systems in which one
star of the pair is a white dwarf, and which often generate bright
and energetic stellar outbursts. Classical novae are one type of
outburst: when the white dwarf accretes enough matter from its
companion, the resulting hydrogen-rich atmospheric envelope
can host a runaway thermonuclear reaction that generates a rapid
brightening1–4. Achieving peak luminosities of up to one million
times that of the Sun5
, all classical novae are recurrent, on timescales
of months6
to millennia7
. During the century before and after an
eruption, the ‘novalike’ binary systems that give rise to classical
novae exhibit high rates of mass transfer to their white dwarfs8
.
Another type of outburst is the dwarf nova: these occur in binaries
that have stellar masses and periods indistinguishable from those
of novalikes9
but much lower mass-transfer rates10, when accretiondisk
instabilities11 drop matter onto the white dwarfs. The coexistence
at the same orbital period of novalike binaries and dwarf
novae—which are identical but for their widely varying accretion
rates—has been a longstanding puzzle9
. Here we report the recovery
of the binary star underlying the classical nova eruption of 11 March
ad 1437 (refs 12, 13), and independently confirm its age by propermotion
dating. We show that, almost 500 years after a classical-nova
event, the system exhibited dwarf-nova eruptions. The three other
oldest recovered classical novae14–16 display nova shells, but lack
firm post-eruption ages17,18, and are also dwarf novae at present.
We conclude that many old novae become dwarf novae for part of
the millennia between successive nova eruptions19,
A nearby yoiung_m_dwarf_with_wide_possibly_planetary_m_ass_companionSérgio Sacani
This document summarizes the identification of two young objects, TYC 9486-927-1 and 2MASS J21265040−8140293, as a likely very wide binary system. It presents revised astrometry showing they have common proper motion. Spectroscopy of the secondary yields a radial velocity consistent with the primary. Analysis of lithium absorption and kinematics suggests an age range of 10-45 Myr, with the secondary having an estimated mass in the planetary mass regime. If confirmed, this would be the widest known exoplanet system at over 4500 AU separation.
A super earth_sized_planet_orbiting_in_or_near_the_habitable_zone_around_sun_...Sérgio Sacani
This document summarizes the discovery of a super-Earth-sized planet orbiting in or near the habitable zone of a Sun-like star called Kepler-69. Using data from the Kepler spacecraft, astronomers detected two planets transiting Kepler-69, called Kepler-69b and Kepler-69c. Kepler-69c is estimated to have a radius of 1.7 Earth radii and orbit every 242.5 days, placing it close to the star's habitable zone where liquid water could exist on the surface. At 1.7 Earth radii, Kepler-69c represents the smallest planet found by Kepler to be potentially habitable, and is an important discovery on the path to finding the first true Earth analog.
Evidence for a_distant_giant_planet_in_the_solar_systemSérgio Sacani
A descoberta de um novo planeta, atualmente não é uma manchete que chama tanto assim a atenção das pessoas. Muito disso, graças ao Telescópio Espacial Kepler, que já descobriu quase 2000 exoplanetas e todo instante uma nova descoberta é anunciada, certo? Mais ou menos, a descoberta anunciada hoje, dia 20 de Janeiro de 2016, é um pouco diferente, pois não se trata de um exoplaneta, e sim de um novo planeta no Sistema Solar, e esse é um fato que intriga os astrônomos a muitos e muitos anos.
Porém, temos que ir com calma com esses anúncios. No artigo aceito para publicação no The Astronomical Journal (artigo no final do post), os autores, Mike Brown e Konstantin Batygin, do Instituto de Tecnologia da Califórnia, apresentaram o que eles dizem ser evidências circunstâncias fortes para a existência de um grande planeta ainda não descoberto, talvez, com uma massa 10 vezes a massa da Terra, orbitando os confins do nosso Sistema Solar, muito além da órbita de Plutão. Os cientistas inferiram sua presença, por meio de anomalias encontradas nas órbitas de seis objetos do chamado Cinturão de Kuiper.
O objeto, que os pesquisadores estão chamando de Planeta Nove, não chega muito perto do Sol, no ponto mais próximo da sua órbita ele fica a 30.5 bilhões de quilômetros, ou seja, cinco vezes a distância entre o Sol e Plutão. Apesar do seu grande tamanho, ele é muito apagado, e por isso ninguém até o momento conseguiu observá-lo.
Não existe ainda uma confirmação observacional da descoberta, mas as evidências são tão fortes que fizeram com que outros especialistas como Chad Trujilo do Observatório Gemini no Havaí e David Nesvorny, do Southwest Research Institute em Boulder no Colorado, ficassem impressionados e bem convencidos de que deve mesmo haver um grande planeta nas fronteiras da nossa vizinhança cósmica.
Kepler-1647b is the largest and longest-period Kepler transiting circumbinary planet discovered to date. It orbits an eclipsing binary star system with an orbital period of approximately 1100 days, making it one of the longest-period transiting planets known. The planet is around 1.06 times the size of Jupiter and perturbes the times of the stellar eclipses, allowing its mass to be measured at 1.52 times that of Jupiter. Despite its long orbital period compared to Earth, the planet resides in the habitable zone of the binary star system throughout its orbit. The discovery of this unusual planetary system provides insights into theories of planet formation and dynamics in multiple star systems.
EXTINCTION AND THE DIMMING OF KIC 8462852Sérgio Sacani
To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star
over a wide wavelength range from the UV to the mid-infrared from October 2015 through December
2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm
fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period
reported is 22.1 ± 9.7 milli-mag yr−1
in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in
the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2
mmag yr−1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at
& 3 σ by three different observatories operating from the UV to the IR. The presence of long-term
secular dimming means that previous SED models of the star based on photometric measurements
taken years apart may not be accurate. We find that stellar models with Tef f = 7000 - 7100 K and
AV ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the
near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from
a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of
the fading favors a relatively neutral color (i.e., RV & 5, but not flat across all the bands) compared
with the extinction law for the general ISM (RV = 3.1), suggesting that the dimming arises from
circumstellar material
The identification of_93_day_periodic_photometric_variability_for_yso_ylw_16aSérgio Sacani
This study identifies a 93 day periodic photometric variability in the Class I young stellar object (YSO) YLW 16A in the Rho Ophiuchus star forming region. Light curve analysis reveals variations of ~0.5 magnitudes in the Ks band over this period. The authors propose a triple system model consisting of an inner binary with a 93 day period eclipsed by a warped circumbinary disk, with a tertiary companion at ~40 AU responsible for warping the disk. This model is similar to one previously proposed for another YSO, WL 4, and may indicate such triple systems with eclipsing disks are common around young stars. Understanding these systems can provide insights into stellar and planetary formation and evolution.
Bright features have been recently discovered by Dawn on Ceres, which extend
previous photometric and Space Telescope observations. These features should produce
distortions of the line profiles of the reflected solar spectrum and therefore an apparent
radial velocity variation modulated by the rotation of the dwarf planet. Here we report
on two sequences of observations of Ceres performed in the nights of 31 July, 26-
27 August 2015 by means of the high-precision HARPS spectrograph at the 3.6-m
La Silla ESO telescope. The observations revealed a quite complex behaviour which
likely combines a radial velocity modulation due to the rotation with an amplitude of
⇡ ±6 m s
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
Is there an_exoplanet_in_the_solar_systemSérgio Sacani
We investigate the prospects for the capture of the proposed Planet 9 from other
stars in the Sun’s birth cluster. Any capture scenario must satisfy three conditions:
the encounter must be more distant than ∼ 150 au to avoid perturbing the Kuiper
belt; the other star must have a wide-orbit planet (a & 100 au); the planet must be
captured onto an appropriate orbit to sculpt the orbital distribution of wide-orbit
Solar System bodies. Here we use N-body simulations to show that these criteria may
be simultaneously satisfied. In a few percent of slow close encounters in a cluster,
bodies are captured onto heliocentric, Planet 9-like orbits. During the ∼ 100 Myr
cluster phase, many stars are likely to host planets on highly-eccentric orbits with
apastron distances beyond 100 au if Neptune-sized planets are common and susceptible
to planet–planet scattering. While the existence of Planet 9 remains unproven, we
consider capture from one of the Sun’s young brethren a plausible route to explain such
an object’s orbit. Capture appears to predict a large population of Trans-Neptunian
Objects (TNOs) whose orbits are aligned with the captured planet, and we propose
that different formation mechanisms will be distinguishable based on their imprint on
the distribution of TNOs
An earth sized_planet_with_an_earth_sized_densitySérgio Sacani
1) Researchers observed the exoplanet Kepler-78b using the HARPS-N spectrograph to measure its mass.
2) They measured Kepler-78b's mass to be 1.86 Earth masses, giving it a density similar to Earth, implying a rocky composition of iron and rock.
3) The small size of Kepler-78b makes it the smallest exoplanet yet measured for both mass and radius, establishing that Earth-sized planets can be terrestrial.
The transit method detects exoplanets by observing periodic dips in a star's light caused by planets passing in front of the star. This method has discovered over 80% of known exoplanets. It allows determining planet properties like radius, atmosphere composition by analyzing light passing through. The Kepler space telescope extensively uses this method to study exoplanet candidates.
The kepler 10_planetary_system_revisited_by_harpsSérgio Sacani
This document discusses observations of the Kepler-10 planetary system made with the HARPS-N spectrograph. The observations resulted in improved precision for the masses of Kepler-10b and Kepler-10c. Kepler-10b's mass was determined to be 3.33 ± 0.49 Earth masses, confirming its rocky composition. Kepler-10c's mass of 17.2 ± 1.9 Earth masses makes it the first strong evidence of a class of more massive solid Neptune-sized planets with longer orbital periods. The improved mass measurements will help constrain models of the internal structure and composition of these planets.
Chiotelis Ioannis, Theodoropoulou Maria, “Searching for Black Holes. Photometry in our Classrooms”, Hellenic Conference on Innovating STEM Education, 16-18 December 2016, Athens, Greece.
The 19 Feb. 2016 Outburst of Comet 67P/CG: An ESA Rosetta Multi-Instrument StudySérgio Sacani
On 19 Feb. 2016 nine Rosetta instruments serendipitously observed an outburst of gas and dust
from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras
and spectrometers ranging from UV over visible to microwave wavelengths, in-situ gas, dust and
plasma instruments, and one dust collector. At 9:40 a dust cloud developed at the edge of an image
in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature
of the outburst that signicantly exceeded the background. The enhancement ranged from 50% of
the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus.
Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest
enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3
and consequently the spacecraft potential changed from 16V to 20V during the outburst. A
clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15
minutes the Star Tracker camera detected fast particles ( 25 ms 1) while 100 m radius particles
were detected by the GIADA dust instrument 1 hour later at a speed of 6 ms 1. The slowest
were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst
originated just outside the FOV of the instruments, the source region and the magnitude of the
outburst could be determined.
The completeness-corrected rate of stellar encounters with the Sun from the f...Sérgio Sacani
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial
velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which
come within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the
Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a
similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars
with large radial velocity uncertainties (>10 km s−1
), and partly because of missing stars in GDR1 (especially at the bright end). The
closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict
a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000–21 000 AU), which will
bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together
with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function
of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars
with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be
545±59 Myr−1
. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds
to 87 ± 9 Myr−1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
A giant ring_like_structure_at_078_z_086_displayed_by_gr_bsSérgio Sacani
This document describes the discovery of a giant ring-like structure in the observable universe displayed by 9 gamma ray bursts (GRBs) between redshifts of 0.78 and 0.86. The ring has a diameter of 1720 Mpc, over five times larger than the expected transition scale to homogeneity. The ring lies at a distance of 2770 Mpc with major and minor diameters of 43° and 30°, respectively. The probability of this structure occurring by random chance is calculated to be 2 × 10-6. This ring-shaped feature contradicts the cosmological principle of large-scale homogeneity and isotropy, and the physical mechanism responsible is unknown.
Confirmation of the_ogle_planet_signature_and_its_characteristics_with_lens_s...Sérgio Sacani
O Telescópio Espacial Hubble e o Observatório W. M. Keck, no Havaí, fizeram confirmações independentes de um exoplaneta orbitando sua estrela central de uma distância bem grande. O planeta foi descoberto através de uma técnica chamada de microlente gravitacional.
Essa descoberta traz uma nova peça para o processo de caçada de exoplanetas: para descobrir planetas longe de suas estrelas, como Júpiter e Saturno estão do Sol. Os resultados obtidos pelo Hubble e pelo Keck apareceram em dois artigos da edição de 30 de Julho de 2015 do The Astrophysical Journal.
A grande maioria dos exoplanetas catalogados são aqueles localizados bem perto de suas estrelas, isso acontece porque as técnicas atuais de se caçar exoplanetas favorecem a descoberta de planetas com curtos períodos orbitais. Mas esse não é o caso da técnica de microlente gravitacional, que pode encontrar planetas mais frios e mais distantes com órbitas de longo período que outros métodos não são capazes de detectar.
A 50000 solar_mass_black_hole_in_the_nucleous_of_rgg_118Sérgio Sacani
Astrônomos usando o Observatório de Raios-X Chandra da NASA e o Telescópio Clay de 6.5 metros no Chile, identificaram o menor buraco negro supermassivo já detectado no centro de uma galáxia. Esse objeto paradoxal poderia fornecer pistas sobre qual o tamanho de buracos negros formados juntos com suas galáxias hospedeiras a 13 bilhões de anos atrás, ou mais.
Os astrônomos estimam que esse buraco negro supermassivo tem cerca de 50000 vezes a massa do Sol. Isso é menos da metade do buraco negro anterior de menor massa encontrado no centro de uma galáxia.
O buraco negro está localizado no centro do disco da galáxia anã, chamada de RGG 118, localizada a cerca de 340 milhões de anos-luz de distância da Terra. A imagem principal desse post, foi feita pelo Sloan Digital Sky Survey e o detalhe mostra uma imagem feita pelo Chandra do centro da galáxia. A fonte pontual de raios-X, é produzida pelo gás quente que faz um movimento de redemoinho ao redor do buraco negro.
Os pesquisadores estimaram a massa do buraco negro estudando o movimento do gás frio perto do centro da galáxia, usando dados na luz visível obtidos pelo Telescópio Clay. Eles usaram os dados do Chandra para descobrir o brilho em raios-X do gás quente espiralando na direção do buraco negro. Eles encontraram que a força de empurrão da pressão da radiação desse gás quente é equivalente a cerca de 1% da força de puxão da gravidade interna, o que se ajusta bem com as propriedades de outros buracos negros supermassivos.
Anteriormente, uma relação tinha sido notada entre a massa dos buracos negros supermassivos e o intervalo de velocidades das estrelas no centro da galáxia hospedeira. Essa relação também é mantida para a RGG 118 e seu buraco negro.
O buraco negro na RGG 118 é cerca de 100 vezes menos massivo do que o buraco negro supermassivo encontrado no centro da Via Láctea. Ele é também cerca de 200000 vezes menos massivo do que o buraco negro mais massivo já encontrado no centro de outras galáxias.
Os astrônomos estão tentando entender a formação de buracos negros com bilhões de vezes a massa solar que têm sido detectados a menos de um bilhão de anos depois do Big Bang. O buraco negro na RGG 118 dá aos astrônomos uma oportunidade de estudar um buraco negro supermassivo, pequeno e próximo, pertencente à primeira geração de buracos negros que não são detectáveis pela nossa tecnologia atual.
Os astrônomos acreditam que buracos negros supermassivos podem se formar quando grandes nuvens de gás, com uma massa entre 10000 e 100000 vezes a massa do Sol, colapsa num buraco negro. Muitos desses buracos negros semeiam então fusões para formar buracos negros supermassivos ainda maiores. De maneira alternativa, um buraco negro supermassivo poderia surgir de uma estrela gigante, com cerca de 100 vezes a massa do Sol, que no final da sua vida, depois de consumir todo o seu combustível, colapsa e forma um buraco negro.
Os pesquisadore
Os astrônomos descobriram um processo único sobre como as maiores galáxias elípticas do universo continuam gerando estrelas muito tempo depois do anos de pico de nascimentos estelares. A alta resolução e a sensibilidade à radiação ultravioleta do Hubble, permitiu aos astrônomos observarem nós brilhantes de estrelas azuis, quentes, se formando juntamente com jatos de buracos negros ativos encontrados nos centros das gigantescas galáxias elípticas.
Combinando dados do Huubble com observações feitas por um conjunto de telescópios baseados tanto em Terra como no espaço, duas equipes independentes descobriram que os jatos dos buracos negros, e as estrelas recém-nascidas são todos partes de um ciclo auto-regulado. Jatos de alta energia atirados do buraco negro aquecem um halo de gás circulante, controlando a taxa com a qual o gás esfria e cai na galáxia.
“Pense no gás ao redor da galáxia como uma atmosfera”, explicou o líder do primeiro estudo, Megan Donahue, da Universidade Estadual do Michigan. “Essa atmosfera pode conter material em diferentes estados, do mesmo modo que a nossa atmosfera tem gás, nuvens e chuva. O que nós estamos vendo é um processo parecido com uma tempestade. À medida que os jatos impulsionam o gás para fora do centro da galáxia, parte do gás esfria e precipita em aglomerados frios que caem de volta para o centro da galáxia como gotas de chuvas”.
“As gotas de chuva eventualmente esfriam o suficiente para tornar-se nuvens de formação de estrelas de gás frio molecular, e a capacidade de observar no ultravioleta distante do Hubble, nos permitiu observar diretamente esses chuviscos de formação de estrelas”, explicou o líder do segundo estudo, Grant Tremblay, da Universidade de Yale. “Nós sabemos que esses chuviscos estão linkados com os jatos, pois eles foram encontrados em filamentos que se dobram ao redor dos jatos, ou abraçam as bordas de bolhas gigantes que os jatos inflaram”, disse Tremblay. “E eles terminam fazendo um redemoinho de gás de formação de estrelas ao redor do buraco negro central”.
Far ultraviolet morphology_of_star_forming_filaments_in_cool_core_brighest_cl...Sérgio Sacani
This document presents a multiwavelength morphological analysis of star-forming filaments in 16 cool core brightest cluster galaxies. New Hubble Space Telescope imaging of far-ultraviolet emission from young, massive stars reveals filamentary and clumpy morphologies. These FUV data are compared with X-ray, Lyα, Hα, optical/IR, and radio maps, providing a high-resolution atlas of star formation locales relative to hot and warm gas phases, old stars, and radio-bright AGN outflows. Nearly half of the sample possesses kpc-scale filaments that extend towards and around radio lobes and/or X-ray cavities, which may have been uplifted or formed in situ by
Confirmation of the_planetary_microlensing_signal_and_star_and_planet_mass_de...Sérgio Sacani
This document summarizes follow-up Hubble Space Telescope observations of the planetary microlensing event OGLE-2005-BLG-169. The HST observations confirm the relative proper motion between the source and lens stars predicted by the planetary signal in the original light curve. This provides the first confirmation of a planetary microlensing signal. The HST observations also measure the brightness of the planetary host star, allowing a precise determination of the planet and host star masses as well as their projected separation. Combined with measurements from Keck adaptive optics, the HST observations confirm the identification of the lens star and characterization of the planetary system.
Discovery and spectroscopy_of_the_young_jovian_planet_51_eri_b_with_the_gemin...Sérgio Sacani
Indo além da descoberta e imageamento de um jovem Júpiter, os astrônomos usando o novo instrumento do Observatório Gemini, Planet Imager, o GPI, eles pesquisaram um mundo recém-descoberto com detalhes sem precedentes. O que eles encontraram é um planeta com cerca de duas vezes a massa de Júpiter, e o exoplaneta mais parecido com um planeta do Sistema Solar já imageado diretamente ao redor de outra estrela.
O exoplaneta, conhecido como 51 Eridani b, orbita sua estrela hospedeira a uma distância equivalente a 13 vezes a distância da Terra ao Sol (o equivalente a uma distância entre Saturno e Urano no nosso Sistema Solar). O sistema está localizado a cerca de 100 anos-luz de distância. Os dados do Gemini, também forneceram aos cientistas as detecções espectroscópicas de metano já detectadas na atmosfera de um planeta fora do nosso Sistema Solar, adicionando mais similaridades desse exoplaneta com os planetas gigantes do nosso Sistema Solar.
Early optical spectra_of_nova_v1369_cen_show_the_presence_of_lithiumSérgio Sacani
O elemento químico lítio foi encontrado pela primeira vez em material ejetado por uma nova. Observações da Nova Centauri 2013 obtidas com o auxílio de telescópios no Observatório de La Silla do ESO e perto de Santiago do Chile, ajudaram a explicar por que é que muitas estrelas jovens parecem ter mais quantidade deste elemento químico do que o esperado. Esta nova descoberta acrescenta uma importante peça que faltava ao quebra-cabeças que representa a evolução química da nossa Galáxia e é um enorme passo em frente na compreensão das quantidades dos diferentes elementos químicos nas estrelas da Via Láctea.
O elemento químico leve lítio é um dos poucos elementos que se prevê ter sido criado pelo Big Bang, há 13,8 bilhões de anos atrás. No entanto, tentar compreender as quantidades de lítio observadas nas estrelas que nos rodeiam hoje tem sido um processo muito difícil. Estrelas mais velhas possuem menos lítio do que o esperado [1] e algumas estrelas jovens têm dez vezes mais lítio do que o que pensávamos [2].
Desde os anos 1970 que os astrônomos especulam que a enorme quantidade de lítio encontrado nas estrelas jovens poderá vir de novas — explosões estelares que libertam material para o espaço entre as estrelas, contribuindo assim para a matéria que forma a próxima geração de estrelas. No entanto, observações cuidadas de várias novas não tinham, até agora, fornecido resultados claros.
Uma equipe liderada por Luca Izzo (Universidade Sapienza de Roma e ICRANet, Pescara, Itália) utilizou o instrumento FEROS montado no telescópio MPG/ESO de 2,2 metros instalado no Observatório de La Silla, assim como o espectrógrafo PUCHEROS montado no telescópio de 0,5 metros do ESO, no Observatório da Pontificia Universidad Catolica de Chile em Santa Marina, perto de Santiago, para estudar a nova Nova Centauri 2013 (V1369 Centauri). Esta estrela explodiu no céu austral perto da estrela brilhante Beta Centauri em dezembro de 2013, tratando-se, até agora, da nova mais brilhante deste século — facilmente observada a olho nu [3].
The harps n-rocky_planet_search_hd219134b_transiting_rocky_planetSérgio Sacani
Usando o espectrógrafo HARPS-N acoplado ao Telescopio Nazionale Galileo no Observatório de Roque de Los Muchachos, nas Ilhas Canárias, os astrônomos descobriram três exoplanetas, classificados como Super-Terras e um gigante gasoso orbitando uma estrela próxima, chamada de HD 219134.
A HD 219134, também conhecida como HR 8832 é uma estrela do tipo anã-K de quinta magnitude, localizada a aproximadamente 21 anos-luz de distância da Terra, na constelação de Cassiopeia.
A estrela é levemente mais fria e menos massiva que o nosso sol. Ela é tão brilhante que pode ser observada a olho nu.
O sistema planetário HD 219134, abriga um planeta gigante gasoso externo e três planetas internos classificados como super-Terras, um dos quais transita em frente à estrela.
Uma equipe de astrofísicos usando o Observatório W. M. Keck no Havaí mediu com sucesso a galáxia mais distante já registrada e o mais interessante, capturou sua emissão de hidrogênio vista quando o universo tinha menos de 600 milhões de anos de vida. Adicionalmente, o método pelo qual a galáxia EGSY8p7 foi detectada dá uma ideia importante sobre como as primeiras estrelas no universo se acenderam depois do Big Bang.
Usando o poderoso espectrógrafo infravermelho do Observatório Keck, chamado MOSFIRE, a equipe datou a galáxia detectando sua linha de emissão Lyman-alpha – uma assinatura do gás hidrogênio quente, aquecido pela forte emissão ultravioleta de estrelas recém-nascidas. Embora, frequentemente seja possível detectar essa assinatura em galáxias próximas da Terra, a detecção da emissão Lyman-alpha nessas grandes distâncias é inesperada, já que ela é facilmente absorvida pelos numerosos átomos de hidrogênio que acredita-se existam no espaço entre as galáxias no nascer do universo. O resultado dá uma nova ideia sobre a reionização cósmica, o processo pelo qual nuvens escuras de hidrogênio foram partidas em seus prótons constituintes e elétrons pelas primeiras gerações de galáxias.
“Nós frequentemente observamos a linha de emissão Lyman-alpha do hidrogênio em objetos próximos já que eles são um dos traçadores mais confiáveis da formação de estrelas”, disse o astrônomo Adi Zitrin, do Instituto de Tecnologia da Califórnia, o Caltech, principal autor do estudo. “Contudo, à medida que penetramos mais fundo no universo, e então voltamos a tempos remotos, o espaço entre as galáxias continha um grande número de nuvens escuras de hidrogênio que absorviam esse sinal”.
An over massive_black_hole_in_a_typical_star_forming_galaxy_2_billion_years_a...Sérgio Sacani
Uma equipe internacional de astrofísicos, liderada por Benny Trakhtenbrot, um pesquiador no Instituto para Astronomia de Zurique ETH, descobriu um gigantesco buraco negro em uma galáxia outrora normal, usando o telescópio Keck I de 10 metros de diâmetro do Observatório W. M. Keck no Havaí. A equipe, conduzindo uma pesquisa rotineira de caça por antigos e massivos buracos negros, foi surpreendida quando encontrou um com uma massa mais de 7 bilhões de vezes a massa do Sol, figurando assim entre os buracos negros mais massivos já descobertos. E pelo fato da galáxia onde ele foi descoberto ser uma galáxia típica em tamanho, o estudo levantou algumas questões sobre as premissas prévias no desenvolvimento das galáxias. As descobertas foram publicadas na revista Science.
Os dados, coletado com o novíssimo instrumento MOSFIRE do observatório Keck, revelou um gigantesco buraco negro na galáxia chamada CID-947 que está a 11 bilhões de anos-luz de distância da Terra. A incrível sensibilidade do MOSFIRE acoplada ao maior telescópio óptico/infravermelho do mundo permitiu que os cientistas pudessem observar e caracterizar esse buraco negro como ele era quando o universo tinha somente 2 bilhões de anos de vida, ou seja, apenas 14% da sua idade atual.
Ainda mais surpreendente que a massa recorde do buraco negro, foi a massa relativamente comum da galáxia que o contém.
A maior parte das galáxias abrigam buracos negros com massas de menos de 1% da massa da galáxia. Na CID 947, a massa do buraco negro é 10% da massa total da galáxia hospedeira. Devido a essa grande disparidade, a equipe deduziu que esse buraco negro cresceu tão rapidamente que a galáxia não foi capaz de pará-lo, levantando assim uma questão sobre o pensamento prévio na co-evolução de galáxias e de seus buracos negros centrais.
Radio imaging obserations_of_psr_j1023_0038_in_an_lmxb_stateSérgio Sacani
Uma estrela super densa formada depois da explosão de uma supernova está expelindo poderosos jatos de material no espaço, sugerem pesquisas recentes.
Num estudo publicado no dia 6 de Agosto de 2015, uma equipe de cientistas na Austrália e na Holanda descobriram poderosos jatos sendo expelidos de uma sistema estelar duplo conhecido como PSR J1023+0038.
Pensava-se anteriormente que os únicos objetos no universo capazes de formar jatos poderosos eram os buracos negros.
O sistema PSR J1023+0038 contém uma estrela extremamente densa que os astrônomos chamam de estrela de nêutrons, numa órbita próxima com uma estrela normal.
Ela foi identificada primeiro como uma estrela de nêutrons em 2009, mas foi somente quando a equipe de pesquisa observou a estrela com o rádio telescópio Very Large Array nos EUA em 2013 e 2014 que eles perceberam que a estrela estava produzindo jatos mais fortes do que se esperava.
Os astrônomos James Miller-Jones, do International Centre for Radio Astronomy Research (ICRAR), disse que as estrelas de nêutrons podem ser pensadas como cadáveres estelares.
“Elas são formadas quando uma estrela massiva esgota todo o seu combustível e vira uma supernova, e as partes centrais da estrela colapsam sobre sua própria gravidade”, disse ele.
“Essas coisas tem normalmente entre uma vez e meia a massa do Sol e somente entre 10 a 15 km de diâmetro, de modo que são extremamente densas”.
Chemical cartography with_apogee_metallicity_distribution_functions_and_the_c...Sérgio Sacani
Cientistas usando o Sloan Digital Sky Survey, o SDSS, criaram um novo mapa da Via Láctea e determinaram que cerca de 30% das estrelas têm mudado dramaticamente suas órbitas. Essa descoberta, publicada na edição do The Astrophysical Journal, traz um novo entendimento sobre como as estrelas se formam, e como elas viajam através da galáxia.
“No nosso mundo moderno, muitas pessoas se mudam do seu lugar de nascimento, no mundo todo”, disse Michael Hayden, da Universidade Estadual do Novo México (NMSU), o principal autor do estudo. “Agora, nós descobrimos que o mesmo é verdade para as estrelas na nossa galáxia – cerca de 30% das estrelas na nossa galáxia têm viajado um longo caminho desde as órbitas onde elas nasceram”.
Para construiu um mapa da Via Láctea, os cientistas usaram o espectrógrafo SDSS Apache Point Observatory Galactic Evolution Explorer (APOGEE) para observar 146000 estrelas durante uma campanha de 3 anos.
Galaxy and mass_assembly_gama_panchromatic_data_release_and__the_low_energy_b...Sérgio Sacani
Uma equipe internacional de astrônomos estudou mais de 200 000 galáxias e mediu a energia gerada numa enorme região do espaço com a maior precisão até hoje. Este estudo representa a estimativa mais completa de produção de energia no Universo próximo. A equipe confirmou que a energia produzida nesta região do Universo de hoje é apenas cerca de metade da produzida há dois bilhões de anos atrás e descobriu que este enfraquecimento ocorre em todos os comprimentos de onda que vão desde o ultravioleta ao infravermelho longínquo. O Universo está morrendo lentamente.
O estudo envolve muitos dos telescópios mais poderosos do mundo, incluindo o VISTA e o VST — os telescópios de rastreio do ESO, instalados no Observatório do Paranal, no Chile. Observações de suporte foram obtidas por dois telescópios espaciais operados pela NASA (GALEX e WISE) e por um outro pertencente à Agência Espacial Europeia (Herschel) [1].
Este trabalho realizou-se no âmbito do projeto Galaxy And Mass Assembly (GAMA), o maior rastreio já realizado em múltiplos comprimentos de onda.
“Usamos tantos telescópios terrestres e espaciais quanto nos foi possível para medir a produção de energia de cerca de 200 000 galáxias ao longo do maior intervalo de comprimentos de onda possível,” disse Simon Driver (ICRAR, The University of Western Australia), que lidera a enorme equipe GAMA.
High resolution alma_observations_of_sdp81_the_innermost_mass_profile_of_the_...Sérgio Sacani
A Campanha de Linha de Base Longa do ALMA produziu uma imagem muito detalhada de uma galáxia distante afetada por lente gravitacional. A imagem mostra uma vista ampliada das regiões de formação estelar na galáxia, com um nível de detalhe nunca antes alcançado numa galáxia tão remota. As novas observações são muito mais detalhadas do que as obtidas pelo Telescópio Espacial Hubble da NASA/ESA e revelam regiões de formação estelar na galáxia equivalentes a versões gigantes da Nebulosa de Orion.
A Campanha de Linha de Base Longa do ALMA produziu algumas observações extraordinárias e coletou informação com um detalhe sem precedentes dos habitantes do Universo próximo e longínquo. Foram feitas observações no final de 2014 no âmbito de uma campanha que pretendeu estudar uma galáxia distante chamada HATLAS J090311.6+003906, também conhecida pelo nome mais simples de SDP.81. A radiação emitida por esta galáxia é “vítima” de um efeito cósmico chamado lente gravitacional. Uma galáxia enorme que se situa entre SDP.81 e o ALMA [1] atua como lente gravitacional, distorcendo a radiação emitida pela galáxia mais distante e criando um exemplo quase perfeito do fenômeno conhecido por Anel de Einstein [2].
Pelo menos sete grupos de cientistas [3] analisaram de forma independente os dados do ALMA sobre SDP.81. Esta profusão de artigos científicos deu-nos informação sem precedentes sobre esta galáxia, revelando detalhes sobre a sua estrutura, conteúdo, movimento e outras características físicas.
O ALMA funciona como um interferômetro, isto é, a rede múltipla de antenas trabalha em sintonia perfeita coletando radiação como se de um único e enorme telescópio virtual se tratasse [4]. Como resultado, estas novas imagens de SDP.81 possuem uma resolução até 6 vezes melhor [5] que as imagens obtidas no infravermelho com o Telescópio Espacial Hubble da NASA/ESA.
The xmm newton-view_of_the_central_degrees_of_the_milk_waySérgio Sacani
Novas imagens do Observatório de Raios-X XMM-Newton da ESA revelaram alguns dos processos mais intensos que acontecem no coração da nossa Via Láctea.
As fontes brilhantes e pontuais que se destacam por toda imagem indicam os sistemas estelares binários onde uma das estrelas atingiu o final de sua vida, desenvolvendo para um objeto compacto e denso – uma estrela de nêutrons ou um buraco negro.
A região central da Via Láctea também contém jovens estrelas e aglomerados estelares e algumas dessas fontes são visíveis como pontos brancos e vermelhos brilhando na imagem, que se espalha por 1000 anos-luz.
A maior parte da ação ocorre no centro, onde nuvens difusas de gás estão sendo cavadas por ventos poderosos soprados por estrelas jovens, bem como por supernovas.
Uma espetacular colisão de galáxias foi descoberta além da Via Láctea. O sistema mais próximo já descoberto, a identificação foi anunciada por uma equipe de astrônomos liderada pelo Professor Quentin Parker da Universidade de Hong Kong e pelo Professor Albert Zijlstra na Universidade de Manchester.
A galáxia está a 30 milhões de anos-luz de distância, o que significa que ela é relativamente próxima. Ela foi chamada de Roda de Kathryn, em homenagem à sua semelhança com o famoso fogo de artifício e também em homenagem à esposa do coautor do trabalho.
Esses sistemas são muito raros e nascem da colisão entre duas galáxias de tamanhos similares. As ondas de choque geradas na colisão comprimem o reservatório de gás em cada galáxia e disparam a formação de novas estrelas. Isso cria um espetacular anel de intensa emissão, e ilumina o sistema, do mesmo modo que a Roda Catherine ilumina a noite num show de fogos de artifício.
As galáxias crescem através de colisões, mas é raro registrar esse processo acontecendo, e é extremamente raro ver o anel da colisão em progresso. Pouco mais de 20 sistemas com anéis completos são conhecidos.
Direct imaging and_spectroscopy_of_a_young_extrasolar_kuiper_belt_in_the_near...Sérgio Sacani
O Cinturão de Kuiper, é a região do Sistema Solar situada além da órbita de Neturno, cerca de 40 UA (1 UA – Unidade Astronômica – é a distância média entre a Terra e o Sol). O Cinturão de Kuiper é o local de numeoroso planetas anões, como Plutão, e é também o lar de milhares de remanescentes das fases iniciais da formação de planetas congelados, que podem fornecer um entendimento fundamental, sobre o nosso Sistema Solar no início de sua vida. Para além do Cinturão de Kuiper, está a Nuvem de Oort, uma nuvem esférica de cometas e planetesimais congelados que se estende talvez a cem mil UA. Provavelmente outros sistemas planetários também contêm regiões análogas ao Cinturão de Kuiper, e elas poderiam ajudar a jogar uma luz sobre a evolução e composição do Cinturão de Kuiper do Sistema Solar. Até agora, contudo, os poucos anéis que se tem imageado não são análogos muito confiáveis, eles têm sido vistos ao redor de estrelas próximas, cujo ambiente de nascimento é diferente do complexo estelar massivo onde o Sol, provavelmente foi formado.
A situação recentemente mudou com o advento de uma nova geração de instrumentos de imageamento astronômico, acoplados aos grandes telescópios que usam sistemas de óptica adaptativa para obter imagens com uma alta resolução espacial. O astrônomo Scott Kenyon do CfA e seus colegas usou o novo espectrômetro montado no Telescópio Gemini para estudar uma estrela um pouco maior que o Sol localizada a cerca de 360 anos-luz de distância num complexo relativamente novo de estrelas massivas, uma região aproximadamente parecida com o suposto local de nascimento do Sol. A estrela tem um grande excesso de emissão infravermelha, uma indicação clara que ela abriga um disco de poeira circunstelar que possivelmente está formando um sistema de planetas.
Os astrônomos imagearam o disco, e encontraram que o anel de detritos está confinado a uma estrutura parecida com o Cinturão de Kuiper. Além disso, eles descobriram a partir do espectro da luz refletida que sua poeira tem propriedades consistentes com os maiores constituintes do Cinturão de Kuiper, incluindo gelo de água. O resultado fornece uma referência promissora para se entender a evolução e a composição do Cinturão de Kuiper, e, para se entender também a evolução inicial do Sistema Solar.
Transit timing observations from kepler i. statistical analysis of the first...Sérgio Sacani
This document analyzes transit timing observations from the first four months of Kepler mission data. It finds that at least 12% (~65) of planet candidates show evidence of transit timing variations (TTVs), suggesting non-Keplerian motion likely due to gravitational interactions with other planets. While longer observation time is needed, TTVs could confirm multiple planet systems identified by Kepler and provide insights into planetary system dynamics and planet formation. The analysis measures individual transit times, assesses the significance of any variations compared to linear and quadratic ephemeris models, and identifies planet candidates warranting further TTV study.
This summarizes a scientific study on long-distance quantum teleportation between two laboratories separated by 55 meters but connected by 2 kilometers of fiber optic cable. The key points are:
1) Researchers teleported quantum states (qubits) carried by photons at 1.3 micrometer wavelengths onto photons at 1.55 micrometer wavelengths between the two laboratories.
2) The qubits were encoded in time-bin superpositions and entanglement rather than polarization to make them more robust against decoherence in optical fibers.
3) A partial Bell state measurement was performed using linear optics at the receiving end to probabilistically teleport the quantum states over the long distance.
Alma observations of_sptdiscovered_strongly_lensed_dusty_star_forming_galaxiesSérgio Sacani
This document summarizes ALMA observations of 4 strongly lensed, dusty, star-forming galaxies discovered by the South Pole Telescope (SPT). ALMA imaging at 860 μm reveals multiple images of each submillimeter source separated by 1-3", consistent with strong lensing. Lens modeling indicates that SPT0346-52 at z=5.7 is one of the most luminous and intensely star-forming sources, with a lensing-corrected luminosity of 3.7 × 1013 L☉ and star formation surface density of 4200 M☉/yr/kpc2. Magnification factors range from 5 to 22, with Einstein radii of 1.1-2.0" and
1) NASA's Kepler mission discovered two distinct transit signals around a bright G-type star, Kepler-10.
2) Statistical tests established the planetary nature of the shorter period signal, now called Kepler-10b.
3) Forty precision Doppler measurements confirmed Kepler-10b, finding it has a radius of 1.416+0.033 R⊕ and is the smallest transiting exoplanet discovered.
A closely packed system of low mass, low-density planets transiting kepler-11Sérgio Sacani
The document summarizes the discovery of six transiting exoplanets orbiting the star Kepler-11. Photometry from the Kepler spacecraft revealed periodic dips in the star's brightness consistent with multiple transiting planets. Six planetary candidates were identified, with orbital periods ranging from 10 to 47 days for the inner five planets. Radial velocity measurements confirmed the planetary nature of the five inner planets and allowed for mass estimates. The outermost sixth planet was also validated as a planet. Analysis of the transit times, durations and depths provided insights into the properties, dynamics, and stability of this unique six-planet system.
The document reports on the Kepler-47 system which consists of two planets orbiting an eclipsing binary star system. The inner planet has a radius of 3.0 Earth radii and orbits every 49.5 days, while the outer planet has a radius of 4.6 Earth radii and orbits every 303.2 days. Eighteen transits of the inner planet were observed, allowing for a detailed characterization of its orbit and that of the binary stars. The timing and duration of the transits vary, indicating the planets orbit both stars in the binary system. Kepler-47 establishes that circumbinary planetary systems can exist around close binary star systems.
The Variable Detection of Atmospheric Escape around the Young, Hot Neptune AU...Sérgio Sacani
This document summarizes observations from the Hubble Space Telescope of the young hot Neptune exoplanet AU Mic b, which orbits the nearby M dwarf star AU Mic. The observations aimed to detect atmospheric escape of neutral hydrogen through absorption in the stellar Lyman-alpha emission line. Two visits were obtained, one in 2020 and one in 2021, corresponding to transits of the planet. A stellar flare was observed and removed from the first visit data. In the second visit, absorption was detected in the blue wing of the Lyman-alpha line 2.5 hours before the white light transit, indicating the presence of high-velocity neutral hydrogen escaping the planet's atmosphere and traveling toward the observer. Estimates place the column density of this material
AT 2022aedm and a New Class of Luminous, Fast-cooling Transients in Elliptica...Sérgio Sacani
This document reports the discovery and follow-up observations of a remarkable fast-evolving optical transient called AT 2022aedm. Key points:
- AT 2022aedm was discovered by the ATLAS survey and reached an extremely luminous peak magnitude of Mg ≈ -22 mag.
- It exhibited an unusually fast rise time of 9 days and faded by 2 magnitudes in the following 15 days.
- Most surprisingly, its host galaxy was found to be a massive elliptical galaxy with negligible star formation.
- Extensive follow-up observations including spectroscopy found it shared properties with two other similar transients in passive galaxies, suggesting a new class of "luminous fast coolers." However
Jupiter’s interior and deep atmosphere: The initial pole-to-pole passes with ...Sérgio Sacani
On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter,
passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter’s
poles show a chaotic scene, unlike Saturn’s poles. Microwave sounding reveals weather
features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow
low-latitude plume resembling a deeper, wider version of Earth’s Hadley cell. Near-infrared
mapping reveals the relative humidity within prominent downwelling regions. Juno’s
measured gravity field differs substantially from the last available estimate and is one
order of magnitude more precise. This has implications for the distribution of heavy
elements in the interior, including the existence and mass of Jupiter’s core. The observed
magnetic field exhibits smaller spatial variations than expected, indicative of a rich
harmonic content.
The Search for Distant Objects in the Solar System Using Spacewatch - Astrono...Eric Roe
This document describes a survey conducted by the Spacewatch Project to search for distant and slow-moving bright objects in the outer solar system beyond Neptune. The survey used data taken over 34 months with multiple night detections to achieve sensitivity to motions as slow as 0.012 arcsec/hr. This allowed the survey to be sensitive to Mars-sized objects out to 300 AU and Jupiter-sized planets out to 1200 AU. No large objects were found at low inclinations despite having sufficient sensitivity, allowing the authors to rule out more than one or two Pluto-sized objects to 100 AU and one or two Mars-sized objects to 200 AU for low inclinations.
Deja vu all_over_again_the_reapperance_of_supernova_refsdalSérgio Sacani
O Telescópio Espacial Hubble das agências NASA e ESA registrou a imagem pela primeira vez da explosão prevista de uma supernova. O reaparecimento da supernova Refsdal foi calculado a partir de diferentes modelos de aglomerados de galáxias, cuja imensa gravidade está entortando a luz da supernova.
Muitas estrelas terminam a sua vida com uma explosão, mas somente poucas dessas explosões estelares têm sido registradas no ato que acontecem. Quando isso acontece, é pura sorte, pelo menos até agora. No dia 11 de Dezembro de 2015, os astrônomos não somente fizeram a imagem de uma supernova em ação, como também observaram quando e onde ela estava prevista para acontecer.
A supernova, apelidada de Refsdal, foi registrada no aglomerado de galáxias, conhecido como MACS J1149.5+2223. Enquanto que a luz do aglomerado gasta cerca de cinco bilhões de anos para chegar até nós, a supernova explodiu muito tempo antes, a aproximadamente 10 bilhões de anos atrás.
A história da Refsdal começou em Novembro de 2014, quando os cientistas registraram quatro imagens separadas da supernova num raro arranjo conhecido como Cruz de Einstein, ao redor de uma galáxia dentro do MACS J1149.5+2223. A ilusão de óptica cósmica ocorreu devido ao fato da massa de uma única galáxia dentro do aglomerado estar entortando e ampliando a luz da distante explosão estelar, num processo conhecido como lente gravitacional.
The Possible Tidal Demise of Kepler’s First Planetary SystemSérgio Sacani
We present evidence of tidally-driven inspiral in the Kepler-1658 (KOI-4) system, which consists of a giant planet
(1.1RJ, 5.9MJ) orbiting an evolved host star (2.9Re, 1.5Me). Using transit timing measurements from Kepler,
Palomar/WIRC, and TESS, we show that the orbital period of Kepler-1658b appears to be decreasing at a rate = -
+ P 131 22
20 ms yr−1
, corresponding to an infall timescale P P » 2.5 Myr. We consider other explanations for the
data including line-of-sight acceleration and orbital precession, but find them to be implausible. The observed
period derivative implies a tidal quality factor
¢ = ´ -
+ Q 2.50 10 0.62
0.85 4, in good agreement with theoretical
predictions for inertial wave dissipation in subgiant stars. Additionally, while it probably cannot explain the entire
inspiral rate, a small amount of planetary dissipation could naturally explain the deep optical eclipse observed for
the planet via enhanced thermal emission. As the first evolved system with detected inspiral, Kepler-1658 is a new
benchmark for understanding tidal physics at the end of the planetary life cycle
O Telescópio Espacial Hubble das agências NASA e ESA registrou a imagem pela primeira vez da explosão prevista de uma supernova. O reaparecimento da supernova Refsdal foi calculado a partir de diferentes modelos de aglomerados de galáxias, cuja imensa gravidade está entortando a luz da supernova.
Muitas estrelas terminam a sua vida com uma explosão, mas somente poucas dessas explosões estelares têm sido registradas no ato que acontecem. Quando isso acontece, é pura sorte, pelo menos até agora. No dia 11 de Dezembro de 2015, os astrônomos não somente fizeram a imagem de uma supernova em ação, como também observaram quando e onde ela estava prevista para acontecer.
A supernova, apelidada de Refsdal, foi registrada no aglomerado de galáxias, conhecido como MACS J1149.5+2223. Enquanto que a luz do aglomerado gasta cerca de cinco bilhões de anos para chegar até nós, a supernova explodiu muito tempo antes, a aproximadamente 10 bilhões de anos atrás.
A história da Refsdal começou em Novembro de 2014, quando os cientistas registraram quatro imagens separadas da supernova num raro arranjo conhecido como Cruz de Einstein, ao redor de uma galáxia dentro do MACS J1149.5+2223. A ilusão de óptica cósmica ocorreu devido ao fato da massa de uma única galáxia dentro do aglomerado estar entortando e ampliando a luz da distante explosão estelar, num processo conhecido como lente gravitacional.
T he effect_of_orbital_configuration)_on_the_possible_climates_and_habitabili...Sérgio Sacani
This research article explores how the orbital configuration of Kepler-62f, a potentially habitable exoplanet in a five-planet system, could affect its climate and habitability. N-body simulations were used to determine the stable range of orbital eccentricities for Kepler-62f. Climate simulations using two global climate models then examined the planet's surface habitability across this range of eccentricities and for different atmospheric compositions. The simulations found multiple combinations of orbital and atmospheric parameters that could allow for surface liquid water on Kepler-62f, including higher orbital eccentricities coupled with high planetary obliquity or atmospheric CO2 levels above 3 bars.
We present the 2020 version of the Siena Galaxy Atlas (SGA-2020), a multiwavelength optical and infrared
imaging atlas of 383,620 nearby galaxies. The SGA-2020 uses optical grz imaging over ≈20,000 deg2 from the
Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 9 and infrared imaging in
four bands (spanning 3.4–22 μm) from the 6 year unWISE coadds; it is more than 95% complete for galaxies larger
than R(26) ≈ 25″ and r < 18 measured at the 26 mag arcsec−2 isophote in the r band. The atlas delivers precise
coordinates, multiwavelength mosaics, azimuthally averaged optical surface-brightness profiles, model images and
photometry, and additional ancillary metadata for the full sample. Coupled with existing and forthcoming optical
spectroscopy from the DESI, the SGA-2020 will facilitate new detailed studies of the star formation and mass
assembly histories of nearby galaxies; enable precise measurements of the local velocity field via the Tully–Fisher
and fundamental plane relations; serve as a reference sample of lasting legacy value for time-domain and
multimessenger astronomical events; and more.
Eccentricity from transit_photometry_small_planets_in_kepler_multi_planet_sys...Sérgio Sacani
Artigo descreve estudo que mostra que a órbita dos exoplanetas terrestres são na sua maioria órbitas circulares, o que é bom para se procurar por vida e o que vem causando uma revolução no entendimento sobre os sistemas de exoplanteas.
This document summarizes the results of a deep near-infrared survey of the Carina Nebula complex using the HAWK-I instrument on the VLT. The survey imaged an area of 0.36 square degrees down to magnitudes of J=23, H=22, and Ks=21, detecting over 600,000 infrared sources. Color-magnitude diagrams of the sources were analyzed to determine properties of the low-mass stellar population such as ages and masses. The survey found that about 3200 sources have masses above 1 solar mass, consistent with expectations from the initial mass function. It also found that about half of the young stars in Carina are in a widely distributed, non-clustered configuration. Six
Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massi...Sérgio Sacani
Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining1. Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability2–5. That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.
Artigo que descreve a descoberta do exoplaneta Kepler-432b, um exoplaneta mais massivo que Júpiter que orbita uma estrela gigante vermelha bem próximo e numa órbita extremamente alongada.
Similar to Kic 9632895 the_10_kepler_transiting_circumbinary_planet (20)
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
PPT on Alternate Wetting and Drying presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
CLASS 12th CHEMISTRY SOLID STATE ppt (Animated)eitps1506
Description:
Dive into the fascinating realm of solid-state physics with our meticulously crafted online PowerPoint presentation. This immersive educational resource offers a comprehensive exploration of the fundamental concepts, theories, and applications within the realm of solid-state physics.
From crystalline structures to semiconductor devices, this presentation delves into the intricate principles governing the behavior of solids, providing clear explanations and illustrative examples to enhance understanding. Whether you're a student delving into the subject for the first time or a seasoned researcher seeking to deepen your knowledge, our presentation offers valuable insights and in-depth analyses to cater to various levels of expertise.
Key topics covered include:
Crystal Structures: Unravel the mysteries of crystalline arrangements and their significance in determining material properties.
Band Theory: Explore the electronic band structure of solids and understand how it influences their conductive properties.
Semiconductor Physics: Delve into the behavior of semiconductors, including doping, carrier transport, and device applications.
Magnetic Properties: Investigate the magnetic behavior of solids, including ferromagnetism, antiferromagnetism, and ferrimagnetism.
Optical Properties: Examine the interaction of light with solids, including absorption, reflection, and transmission phenomena.
With visually engaging slides, informative content, and interactive elements, our online PowerPoint presentation serves as a valuable resource for students, educators, and enthusiasts alike, facilitating a deeper understanding of the captivating world of solid-state physics. Explore the intricacies of solid-state materials and unlock the secrets behind their remarkable properties with our comprehensive presentation.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
1. Draft version September 8, 2014
Preprint typeset using LATEX style emulateapj v. 5/2/11
KIC 9632895 – THE 10T H
KEPLER TRANSITING CIRCUMBINARY PLANET
William F. Welsh, Jerome A. Orosz, Donald R. Short
Department of Astronomy, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1221
William D. Cochran, Michael Endl, Erik Brugamyer
McDonald Observatory, The University of Texas as Austin, Austin, TX 78712-0259
Nader Haghighipour
Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822, USA
Lars A. Buchhave
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA, and Centre for Star and Planet Formation,
Natural History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark
Laurance R. Doyle
SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043; and Principia College, IMoP, One Maybeck Place, Elsah, Illinois
62028
Daniel C. Fabrycky
Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637
Tobias Cornelius Hinse
Korea Astronomy and Space Science Institute, 776 Daedukdae-ro, Yuseong-gu 305-348, Daejeon, Republic of Korea, and Armagh
Observatory, College Hill,BT61 9DG, Armagh, NI, UK
Stephen Kane
Department of Physics & Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
Veselin Kostov
Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218
Tsevi Mazeh
School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
Sean M. Mills
Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637
Tobias W. A. Mueller
Institute for Astronomy and Astrophysics, University of Tuebingen, Auf der Morgenstelle 10, D-72076 Tuebingen, Germany
Billy Quarles
NASA Ames Research Center, Moffet Field, CA 94035, USA
Samuel N. Quinn
Department of Physics & Astronomy, Georgia State University, 25 Park Place NE Suite 600, Atlanta, GA 30303; NSF Graduate
Research Fellow
Darin Ragozzine
Florida Institute of Technology, Department of Physics and Space Sciences, 150 W. University Blvd., Melbourne, FL 32901
Avi Shporer1
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA; and Division of
arXiv:1409.1605v1[astro-ph.EP]4Sep2014
2. 2
Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
Jason H. Steffen
Lindheimer Fellow, CIERA, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
Lev Tal-Or
School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
Guillermo Torres
Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138
Gur Windmiller
Department of Astronomy, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1221
William J. Borucki
NASA Ames Research Center, Moffet Field, CA 94035, USA
Draft version September 8, 2014
ABSTRACT
We present the discovery of KIC 9632895b, a 6.2 R⊕-radius planet in a low-eccentricity, 240.5-day
orbit about an eclipsing binary. The binary itself consists of a 0.93 and 0.194 M pair of stars with
an orbital period of 27.3 days. The plane of the planet’s orbit is rapidly precessing, and its inclination
only becomes sufficiently aligned with the primary star in the latter portion of the Kepler data. Thus
three transits are present in the latter half of the light curve, but none of the three conjunctions that
occurred during the first half of the light curve produced transits. The precession period is ∼103 years,
and during that cycle, transits are visible only ∼8% of the time. This has the important implication
that for every system like KIC 9632895 that we detect, there are ∼12 circumbinary systems that exist
but are not currently exhibiting transits. The planet’s mass is too small to noticeably perturb the
binary, consequently its mass is not measurable with these data; but our photodynamical model places
a 1-σ upper limit of 16 M⊕. With a period 8.8 times that of the binary, the planet is well outside the
dynamical instability zone. It does, however, lie within the habitable zone of the binary, and making
it the third of ten Kepler circumbinary planets to do so.
Subject headings: binaries: close, eclipsing — planets and satellites: detection, dynamical evolution
and stability — stars: individual (KIC 9632895, Kepler-nnnn)
1. INTRODUCTION
In its quest to find habitable worlds, the Kepler Mission
(Borucki et al. 2010; Koch et al. 2010) has observed over
2600 eclipsing binary star systems. Cataloged in Prˇsa et
al. (2011), Slawson et al. (2011), and Kirk et al. (2014),
the vast majority of these are new systems discovered by
Kepler, and have orbital periods between 1.8 hours to 670
days. A sizeable fraction (∼20-30%) exhibit evidence for
being triple or higher multiplicity stellar systems (Con-
roy et al. 2013; Rappaport et al. 2013; Gies, et al. 2012;
Orosz et al. in prep). In addition, there is a rapidly grow-
ing subset where the third body is a planet rather than
a star. Beyond providing challenges to planet-formation
theory (e.g. Kley & Haghighipour 2014), these circumbi-
nary planets are particularly important because the or-
bital configurations and 3-body gravitational interactions
allow direct and precise measurements of the mass and
radius of the bodies. For example, in the Kepler-34 sys-
wwelsh@mail.sdsu.edu, jorosz@mail.sdsu.edu
1 Sagan Fellow
Based on observations obtained with the Hobby-Eberly Tele-
scope, which is a joint project of the University of Texas at
Austin, the Pennsylvania State University, Stanford University,
Ludwig-Maximilians-Universit¨at M¨unchen, and Georg-August-
Universit¨at G¨ottingen.
tem the relative uncertainties in the stellar masses and
radii are less than 0.3% (Welsh et al. 2012); for Kepler-
16 the uncertainties in the planet’s mass and radius are
4.8% and 0.34%, respectively (Doyle et al. 2011).
To date, nine transiting circumbinary planets have
been discovered, residing in seven systems: Kepler-16b
(Doyle et al. 2011), Kepler-34b and 35 b (Welsh et
al. 2012), Kepler-38b (Orosz et al. 2012b), Kepler-47b
and c (Orosz et al. 2012a), Kepler-64b (Schwamb et al.
2013 and simultaneously Kostov et al. 2013), Kepler-
413b (Kostov et al. 2014), and Kepler-47d (Orosz, in
prep). The transiting nature of these planets unambigu-
ously confirms the presence of the third orbiting body.
However, due to dynamical interactions, a transiting cir-
cumbinary planet may not always transit — in Kepler-
413 three transits were observed with a period of ∼66
days, then for 800 days no transits were present, then
five more transits were observed. This behavior is due
to the 2.5 degree angle between the planet and binary
orbital planes which, for Kepler-413, leads to precession
with a period of only 11 years (Kostov et al. 2014).
In the following sections we present the discovery of
the tenth Kepler transiting circumbinary planet, Kepler-
nnnn (KIC 9632895). The tight constraints placed on the
relative positions, velocities, and sizes of the three bodies
3. 3
by the times, durations, and depths of the eclipses and
transits allow very precise determinations of the geomet-
ric aspects of the system. As will be shown below, the
uncertainty in the planet’s radius is only 0.57%, and for
the secondary star’s radius it is 0.65%, making it one of
the most precisely measured low-mass stars. Like Kepler-
413, this system also exhibits times when no transits are
present during conjunctions of the planet with the bi-
nary. In §2 we present the observations, in §3 we detail
the photodynamical modeling of the observations. We
present the results in §4 and discuss the characteristics
of the binary and the planet, the orbital dynamics and
the long-term stability. We conclude with a section de-
scribing KIC 9632895-b’s status as the third circumbi-
nary planet in the habitable zone.
2. OBSERVATIONS
2.1. The Kepler Light Curves
Identification of KIC 9632895 as a circumbinary planet
candidate was made by visual inspection of a subset of
the Kepler eclipsing binary star light curves (Slawson et
al. 2011), in particular, those with orbital periods greater
than ∼1 day that show both primary and secondary
eclipses. Once identified as a circumbinary planet candi-
date, the system was given the KOI number 3151, though
this same system had previously been named KOI-1451
and rejected as a false-positive; thus KOI-1451 is formally
the correct KOI number. Because we identified the bi-
nary as a circumbinary planet candidate, the target was
placed on Short Cadence (∼1 min integration sampling)
starting in Quarter 13 (2012 March 29). The NExScI
Exoplanet Archive lists for KOI-1451 a Kepler magnitude
of 13.552, temperature of Teff = 5618 K, and a surface
gravity of log g = 4.586, while the Mikulski Archive for
Space Telescopes (MAST) reports Teff = 5425 K and
log g = 4.803. Note that in their study on the rate of
occurrence of circumbinary planets, Armstrong, et al.
(2014) independently identified KIC 9632895 as a cir-
cumbinary planet candidate.
The orbital period of the binary is 27.322 days and
the depth of the primary eclipse is ∼ 8%. The secondary
eclipse is shallow, only ∼ 0.25%, and flat-bottomed, indi-
cating a total eclipse. Since the primary eclipse is likely
to be total (i.e. annular), the depth of the eclipses tells
us that the secondary star contributes only a small frac-
tion to the total luminosity and is likely a low-mass small
star.
The upper panel of Fig. 1 shows a one-year long sec-
tion of the light curve, after normalizing each Quarter
with a simple cubic polynomial. The light curve exhibits
quasi-periodic variations of ∼0.5% on a timescale of tens
of days, with the largest peak-to-peak variation being
∼1.5%. The rms of the mildly detrended PDC-MAP
light curve, after removing all the eclipses, is 0.22%. We
interpret these modulations as being caused by starspots
on the primary star.
The lower panels of Fig. 1 show a sample of eclipse
events, all in Short Cadence, along with our best-fit
model curve. The leftmost is a secondary eclipse, fol-
lowed by a planet transit, then two primary eclipses. The
time scale in each panel is identical and nicely demon-
strates the much longer duration of the transit than that
of the eclipses. The two primary eclipses are consecu-
tive in time, yet the first shows a notable deviation in
its residuals. This is the signature of a starspot on the
primary star being occulted by the secondary star. Such
events are common, but are not readily visible in Long
Cadence eclipse profiles.
Fig. 2 shows the phase-folded eclipse profiles, based on
the Long Cadence Kepler observations that span 1470.5
days (from times -46.5 to 1424.0 in BJD–2,455,000). The
preliminary model fit to the binary star data only (no
planet included) is generally excellent, though there is
a marked increase in the scatter of the residuals for the
primary eclipse. These are due to the secondary star cov-
ering starspots (and possibly other features) on the pri-
mary star. Our ELC photodynamical model, described
in §3, does not include starspots, thus the minimization
of residuals leads to both high and low scatter. If we were
to use this preliminary fit, we would need to correct for a
bias in the model – the starspots should induce upward-
only residuals, and as this is not the case, the model
is too shallow compared to the true eclipse depth. It
is important to note that the starspot-occultations lead
not only to residuals in flux, but also to shifts in the
measurements of the timing of the eclipses. We return
to this point in §3 when describing our photodynamical
modeling methodology.
The center-of-eclipse times for the 49 primary and 50
secondary eclipses were measured in two ways: (i) by us-
ing the best-fit model eclipse profile (described in §3) as
a template and sliding it to best match the individual
eclipses; and (ii) using the technique described in Steffen
et al. (2011) and Welsh et al. (2012), which uses a tem-
plate created from a polynomial fit to the folded eclipse
profile. The results were very comparable, so we adopt
the former method because it should be less-sensitive
to starspot-induced deviations in the mean eclipse pro-
file. The mean uncertainty is 6.8 seconds for the pri-
mary eclipses (7.6 s for the 34 Long Cadence eclipses,
4.3 s for the 12 Short Cadence eclipses). The shallow-
ness of the secondary eclipses made their timing mea-
surements much more difficult: the mean uncertainty is
117.3 s (123.5 s for the 37 Long Cadence eclipses, 99.7 s
for the 13 Short Cadence eclipses).
A linear ephemeris was derived from the eclipse times
and a time series of Observed minus Computed (O − C)
values was made. When compared with the local slope
of the light curve surrounding each primary eclipse, the
O−C times show a significant anti-correlation. This anti-
correlation indicates that the spin of the star is prograde
with respect to the binary orbit (Holczer et al. 2014; see
also Sanchis-Ojeda, et al. 2012). Such behavior was also
seen in Kepler-47 (Orosz et al. 2012a). Using a linear
fit to the primary star O − C values versus the local
slopes, the eclipse times were then statistically corrected
for the starspot-induced timing shifts; the uncertainties
in the times were increased (by ∼10 s in quadrature) to
account for noise in this correction. The eclipse measure-
ments made after date BJD–2455000=1015 used Short
Cadence observations, though because of the boosting
of the uncertainties in the starspot correction, the error
bars are similar to those of the Long Cadence O − C.
The secondary eclipse O − C values were not correlated
with their local slope, so no correction was made. A com-
mon linear ephemeris was then fit to both sets of eclipse
times, and Fig. 3 shows the resulting O − C diagram.
4. 4
The rms of the O − C residuals is 10.1 s for the primary
and 100.0 s for the secondary, and both appear consistent
with noise. This indicates that the circumbinary object
has no measurable gravitational effect on the binary, at
least on a timescale of a few years. Consequently, the
object is of relatively low mass and only an upper limit
on its mass can be robustly determined.
The Kepler Simple Aperture Photometry “SAP” data
were used throughout this paper, with the exception
of measuring the starspot modulation rms amplitude.
The light curve was detrended and normalized using the
method described in Orosz et al. (in prep): windows
around each eclipse event were kept and the rest of the
light curve discarded. The windows were three times the
width of the eclipse. Data that were inside an eclipse
were then masked, and for each window, a 5th order
Legendre polynomial was fit. The eclipse was then re-
stored and the data normalized by dividing by the poly-
nomial. Any points with a Kepler pipeline Data Quality
flag greater than 16 (indicative of some anomaly with
the observation) were omitted prior to the detrending.
The mean Combined Differential Photometric Precision
(CDPP) over a 3-hour baseline as reported on MAST is
121 ± 34 ppm. Prior to the eclipse and transit fitting, the
light curve was heavily detrended (to minimize starspot
effects) and normalized. The rms scatter outside of the
eclipse and transit events was measured to be 0.0159 %
(159 ppm), consistent with the CDPP value, and was a
factor of 1.17 times larger than the mean SAP error bar.
This difference suggests that either the SAP error bars
are slightly underestimated or there are additional high-
frequency variations that the detrending did not remove.
2.2. High Resolution Spectroscopy
KIC 9632895 was observed from the McDonald Ob-
servatory with the High Resolution Spectrograph (Tull
1998) on the Hobby-Eberly Telescope (HET), and with
the Tull Coude Spectrograph (Tull et al. 1995) on the the
Harlan J. Smith 2.7 m Telescope (HJST). A total of 11
spectra were obtained in 2013, spanning 47 nights. The
HRS spectra cover a wavelength range from 4780 to 6800
˚A at a resolving power of R = 30, 000 and a typical con-
tinuum signal-to-noise (S/N) ratio of 40:1 at 5500 ˚A. The
data taken with the Tull spectrograph span the entire op-
tical spectrum and have a resolving power of R = 60, 000
with a typical continuum S/N ratio around 20:1 at 5500
˚A. We determined the RVs by cross-correlating the spec-
tra with the RV standard star HD 182488. Eleven radial
velocities were extracted (note: a 0.185 km s−1
zero-
point offset was found between the two spectrographs).
As expected from the light curve, the secondary star is
sufficiently faint that it was not detected in the spec-
tra. By injecting a synthetic spectrum signal into the
observed spectra and attempting to recover that signal,
an upper limit of ∼ 4% was found for any non-primary
star light. This upper limit is over an order of magnitude
higher than the secondary star’s light contribution esti-
mated via the photodynamical modeling described in §3,
and therefore this is not valuable in determining the sec-
ondary star’s flux contribution. However, it is interesting
with regard to the presence of any contaminating third
light. The radial velocities for the primary are listed in
Table 1 and the ELC model fit (§3.1) is shown in Fig. 4.
Several independent spectral analyses were carried out
using the higher signal-to-noise HET spectra, includ-
ing an SPC (Stellar Parameter Classification) analysis
(Buchhave et al. 2012), an analysis similar to the one
for KOI-126 (Carter et al. 2011), a MOOG-based analy-
sis and by fitting a theoretical template to the spectrum
(Tal-Or et al. 2013). Each gave similar results, with the
best fit Teff ranging from 5480 - 5620 K, and metalicity
[m/H] ranging from -0.10 to +0.09. The spectra have
relatively low S/N ratio for this type of spectral analysis
and the SPC method has worked reliably on noisy data,
hence we prefer its results: Teff = 5527 ± 50 K, [m/H] =
+0.09 ± 0.08, and log g = 4.56 ± 0.10. This surface grav-
ity measurement was guided, but not constrained by, the
photodynamical modeling value of log g = 4.57. The
agreement in metallicity between methods was not as
tight as for Teff , thus we conservatively inflate the uncer-
tainty in both metallicity and Teff to ±0.1 and ±100 K,
respectively. In addition, the projected stellar rotation
velocity, Vrot sin i, was measured to be 1.9 km s−1
.
2.3. Direct Imaging
Based on the values retrieved from MAST, the sea-
sonal mean of the contamination for KIC 9632895 is 7.0
± 1%. Such contamination will dilute the eclipse and
transit depths and could significantly bias the inferred
radii. Therefore we undertook several direct imaging in-
vestigations to determine the amount of contamination.
Eighteen short exposures (10 s) of the target were ob-
tained in the SDSS-r filter using the LCOGT (Brown et
al. 2013) FTN 2m robotic telescope in Haleakala, Hawaii
over the span of 4 nights in 2012 March. The data were
median-combined and provided an image with a FWHM
of 1.70 arcsec. According to the KIC there should be a
∆Kp = 2.8 mag fainter star located 4.5 arcsec south of
the target (KID 9632896; g-r = 4.4 mag). This star was
not detected, although fainter stars further away were
clearly detected. The closest star to the target in the
image is about 15 arcsec away and has r=18.3 mag ac-
cording to the KIC. That star is also the closest star to
the target detected by the UBV survey of Everett et al.
(2012).
To better understand any photometric contamination
due to non-target light captured in the Kepler aperture,
we observed KIC 9632895 through J, H and Ks filters on
the WIYN High-Resolution Infrared Camera (WHIRC
– Meixner et al. 2010) at the Kitt Peak National Ob-
servatory on 2013 Oct 19 UT. We employed a standard
five-point dithering pattern and 30 s exposure times in
each filter. Unfortunately the conditions were not pho-
tometric and the seeing was ∼0.9 arcsec. We estimated
detection limits in each filter following the procedure of
Adams et al. (2012). We used the IDL aper routine
to measure the contribution from the target’s PSF in
non-overlapping, concentric annuli centered on the star.
We define a detection limit as a 5-σ signal above the
measured stellar PSF background in each annulus. The
innermost annulus in each filter is defined as the mea-
sured FWHM of the stellar PSF. The detection limits
are presented in Table 2. The expected nearby star KIC
9632896 was again not detected. A star ∼ 8.5 arcsec
away toward the SW was detected in the J band (and
weakly in the H band and barely in the K band), with
∼0.5% the brightness of KIC 9632895.
5. 5
Finally, an even deeper J-band observation was taken
with UKIRT as part of the J-band survey of the Kepler
field for the UKIDDS Survey. The J-band detections
were converted into expected Kepler magnitudes via the
transformations from Howell et al. (2012). The missing
KIC star was again not detected. The star 8.5 arcsec
away was detected (expected Kepmag=19.12, based on
the J-mag 17.64 observation), along with a very faint
star 7.26 arcsec due south of KIC 9632895, with an ex-
pected Kepmag of 19.85. In summary, the star reported
as KIC 9632896 was not detected, and no stars were de-
tected that could contribute any significant contamina-
tion within the Kepler aperture.
3. PHOTODYNAMICAL MODELING
Though eclipsing, KIC 9632895 is a single-lined spec-
troscopic binary, which normally does not allow a full
solution of the component masses. However, the pre-
cise times and durations of the planetary transits place
strong constraints on the location and relative velocity of
the primary star, which in turn constrains the mass ra-
tio. Additionally, the light-travel time effect further con-
strains the mass ratio. Thus a full solution for the eclips-
ing binary is possible with a photodynamical model.
3.1. The ELC Photodynamical Model
An upgraded “photodynamical” version of the ELC
code (Orosz & Hauschildt 2000) was developed. The up-
grade allows for dynamics, instead of Keplerian kinemat-
ics, by integrating the Newtonian equations of motion
under the assumption of point-masses and Newtonian
gravity. A 12th
order Gaussian Runga-Kutta symplectic
integrator, based on the code of E. Hairer and M. Hairer
(2003) is used.
Transits and eclipses are modeled using the pre-
scription of Mandel & Agol (2002), replacing the
Gimenez method (Gimenez 2006) formerly used in ELC.
Quadratic limb darkening is used, following the method
of Kipping (2013), which more naturally handles correla-
tion and limits on the coefficients. A total of 26 param-
eters are specified in the model: the five standard Ke-
plerian orbital parameters for each orbit (P, Tc, i, e, ω),
the three masses, the three radii, the stellar temperature
ratio, two quadratic limb darkening coefficients for each
star, the longitudinal nodal angle Ω of the planet’s orbit,
and four seasonal contamination levels. Since the Kep-
lerian parameters evolve rapidly with time, their values
presented in Table 3 are instantaneous “osculating” val-
ues valid at the reference epoch. In particular, the time of
conjunction, Tconj, is the time of conjunction of the body
and the barycenter; for the binary this is approximately
a primary mid-eclipse time, but for the planet it need
not be close to an actual transit. Furthermore, while
this fiducial time serves to set the position of the planet
in its orbit at the reference epoch, it does not accurately
define the planet’s position when the model is integrated
away from the reference time. To faithfully reproduce
our solution the instantaneous positions and velocities
given in Table 4 should be used. Although the nodal
longitude of the binary is not measurable with our data,
it must be specified; we set the angle to be zero. In the
actual fitting, ratios and other combinations of parame-
ters are often more robustly constrained by the data, e.g.
mass ratios, semi-major axis/radius, temperature ratio,
e cos ω, and e sin ω, and these are therefore used. Both a
genetic algorithm and a Markov Chain Monte Carlo op-
timization was used to explore parameter space and find
the least-squares best solution, along with the uncertain-
ties, defined as the interval for which the χ2
is less than
the minimum χ2
+ 1 for each marginalized parameter.
3.2. Photodynamical Fitting Strategy
We initially fit the normalized and detrended Kepler
Long Cadence light curve plus the 11 radial velocity val-
ues. Because the normalized flat sections of the light
curve far from any eclipse or transit contain no informa-
tion on the system parameters, they were omitted from
the fitting process. The uncertainties in the Kepler data
were increased to account for additional “noise” that oc-
curs when a starspot is eclipsed (see Fig. 2). An increase
of 1.44 was chosen to give a reduced χ2
≡ 1.0, based on
a preliminary model fit to the eclipses. Our initial fit
was acceptable, yielding a χ2
of 11,114.6 for 11,139 data
points. However, we found the results unsatisfactory for
the following reason: The best fit estimate for the mass
of the planet was tightly constrained to zero mass. When
the non-negative mass constraint was lifted, the preferred
solution fell to roughly −90M⊕, at an unnerving 3-σ con-
fidence. Three scenarios were considered to explain this
non-physical result, keeping in mind that any constraint
on the mass of the planet arises from the perturbation the
planet induces on the binary, which would be manifest
most readily in the eclipse timing variations (ETVs).
The first scenario presumed that the binary apsidal
motion was not being calculated sufficienly well in the
model, and the disagreement between the predicted and
measured divergence in the O − C diagram was leading
to the non-physical mass. For the separation and radii of
the stars, classical apsidal motion due to tides was found
to be negligible, but the precession caused by general
relativity (GR) was potentially signicant. This led to
the inclusion of a GR correction in the model (Mardling
& Lin 2002; see also Ragozzine & Wolf 2009 and Hilditch
2001). However, the O−C of the ETVs is essentially flat,
and the inclusion of GR increases the apsidal motion rate,
thus having the effect of nudging the planet’s mass lower.
The amplitude of the effect is nearly negligible however.
Nevertheless, GR is included as a necessary component
for a more realistic model.
The second scenario was based on the premise that the
starspots on the primary were affecting the times of the
primary eclipses. Spurious correlated variations in the
ETV could mimic the effect of a negative mass planet.
This led us to re-measure the eclipse times using a differ-
ent method and more carefully correct for the starspot-
induced variations (see Mazeh, Holczer, Shporer 2014).
The re-measurements were very similar to the original
values, giving us more confidence in their validity. Nev-
ertheless, the correlation between the ETVs and the lo-
cal light curve slope indicates that starspots are affect-
ing the eclipse times. The first Short Cadence primary
eclipse shown in Fig. 1 illustrates this very well. Thus
the primary eclipses are “contaminated” with noise due
to starspot occultations, and their reliability is less than
ideal. To mitigate this problem, we chose to fit only three
primary and secondary eclipses that showed very clean
residuals. These Short Cadence data are shown in Fig. 5.
With the superb Kepler photometry, these six eclipses
6. 6
are sufficient to measure all the geometric binary system
parameters. To capture the effect of the planet on the
binary (the only way to measure its mass in this single-
planet system), we include as part of the data all the
eclipse times. The model is then penalized in a χ2
sense
if its predicted eclipse times do not match the observed
eclipse times. (The same 1.44 boost factor on the Kepler
SAP error bars was maintained, for both the Long and
Short Cadence.) As with the radial velocity observations,
the eclipse times were given equal weight per point as the
photometric data, i.e., no regularization of the different
data sets were enforced. With this new strategy for mod-
eling the data, the dynamical constraints in the data are
preserved, even though the individual eclipses are not
fit. The key advantage of this method is that it uses
primary eclipse times that have been corrected for the ef-
fect of starspots. The individual eclipse profiles cannot
be corrected for the effect of starspots without employ-
ing a prohibitively computationally-expensive evolving-
starspot model, requiring at least a dozen additional free
parameters for even a rather simple two-starspot charac-
terization (i.e, starspot latitudes, longitudes, radii, tem-
peratures, onset times, lifetimes, etc.) And so, using this
strategy, our photodynamical model now prefers a much
larger mass for the planet, and while the mass is still
close to zero, the uncertainty is ±16 M⊕, a much more
plausible result. This is the methodology and solution
we adopt.
For completeness we briefly mention the third scenario
we considered, which was the inclusion of a possible sec-
ond planet external to the observed one. Naturally, the
freedom such a model allows provided a much better
match to the observations – formally an improvement of
100 in χ2
when fitting to all of the eclipses. Both planets
had small but positive mass (uncertainty of a few M⊕),
and the period of the hypothetical second planet was
∼404 days – interesting if true, as this is a period ratio
of 1.68, which is a 5:3 ratio. However, we discard the
second planet hypothesis because when using only the
eclipse times and three clean eclipses as discussed above,
the improvement is only 3.3 in χ2
, far from being sig-
nificant when the additional 7 free parameters are taken
into account
3.3. Fitting Assessment
Using the Short Cadence data when possible, there are
18,472 Kepler photometric data points, plus 11 radial ve-
locities and 96 eclipse times. As evident in Fig. 1, 4, 5
and 6, the ELC photodynamical model provides a good
fit to the eclipse profiles, times of eclipse, radial veloc-
ities, and transits. Formally, the model fit yields a χ2
of 18725.9, or a reduced χ2
of 1.0093. In particular, the
model matches the transit timing variations (TTVs) and
the transit duration variations (TDVs). The time inter-
val between the first two transits is 237.35 days, while the
interval between the second and third transits is 235.56
days. The variation in transit duration is even more ex-
treme, changing from 5.7 hours to 12.5 hours (see Fig. 6).
Table 5 lists the observed transit times, durations, and
depths, and the predicted values from the photodynam-
ical model. The large TTVs and the more than a factor
of two difference in the duration of the transit are due
to the “moving target” effect — the motion of the pri-
mary star about the barycenter. Thus the TTVs and
TDVs follow well-defined curves as functions of the or-
bital phase of the binary and constitute an unambiguous
signal of a circumbinary object, as no known false posi-
tive can reproduce this effect. This “smoking gun” signa-
ture will remain approximately true even in the presence
of additional planets. However, if the transiting planet’s
orbit is significantly tilted with respect to the binary’s
orbit, the precession timescale may be sufficiently short
that the changing impact parameter will alter the tran-
sit durations. In some cases, such as in Kepler-413, and
now also in KIC 9632895, the orbit precesses such that a
large fraction of the time the planet does not transit the
primary. We return to this topic in §4.3.
Finally, the parameters from the photodynamical solu-
tion were input into the photodynam code of Josh Carter
that was used to model the previous Kepler circumbi-
nary planets (Carter et al. 2011; P´al 2012) and yielded
good matches to the light curve. In addition, another
completely independent photodynamical code developed
by one of us (SMM), has been used to test and confirm
the validity of the ELC code.
4. RESULTS AND DISCUSSION
While the circumbinary configuration can in principle
allow very accurate and precise estimates of the masses
and radii of the three bodies, for KIC 9632895 the sec-
ondary star’s radial velocity is not measured and there
are only three planetary transits across the primary and
none across the secondary. (The secondary star is so
faint compared to the primary that transits over the
secondary would not be detectable with these Kepler
data; one such unseen transit did occur near date BJD–
2,455,000 = 548.974) The reflected light from the planet
is far too feeble to allow the detection of any occultations.
And the planet does not noticeably perturb the binary,
thus its mass can only be constrained by limits on the
eclipse timing variations, light travel time effects, pre-
cession timescales, and stability arguments, all of which
are subtle. However, the phasing of the three transits
is excellent, covering nearly the minimum to maximum
possible duration and, importantly, there are three con-
junctions where there is no observed transit. The lack of
these three transits is itself an important constraint.
While ELC prefers a near zero-mass planet, the uncer-
tainty of 16 M⊕ means that an anomalously low mass
(and density) planet is not required. Perhaps equally
significant, the model demands a planet with a mass far
less than a Jupiter mass, ruling out any possibility of the
circumbinary object being stellar.
4.1. The Eclipsing Binary
The secondary star has a mass M2 = 0.194 ± 0.002M
and radius R2 = 0.214 ± 0.001R , making it one of the
lowest-mass stars with a precise (<5% uncertainty) dy-
namical mass and radius determination. It is just slightly
less massive than Kepler-16 B (0.20255 M ; Doyle et al.
2011; see also Winn et al. 2011 and Bender et al. 2012),
KOI-126 C (0.2127 M ; Carter, et al. 2010), which in
turn is very slightly smaller than CM Dra B,A (0.2141
and 0.2310 M ; Morales et al. 2009). The ELC model
provides a temperature ratio of T2/T1=0.599, which,
combined with the spectroscopically measured Teff of
5527 K for the primary, gives a Teff of 3309 K for the
secondary star.
7. 7
Dartmouth stellar evolution models (Dotter et
al. 2008) were compared with the measured mass, ra-
dius, temperature and metallicity of the stars (we are
assuming no alpha-element enhancement), and the re-
sults are shown in Fig. 7, in the form of a radius versus
mass diagram. The best-matching isochrone was found
by minimizing the distance between the observed value
and the interpolated isochrones.“Distance” is defined as
the quadrature sum of the uncertainty-normalized devi-
ations between the isochrone and the observed masses,
radii, and temperatures, for a fixed metalicity. Three
isochrones are shown in Fig. 7: the first is a match to
the primary star only (solid curve) for a [Fe/H]=0.09,
which is the best estimate of the star’s metallicity. This
isochrone has a best temperature of 5429 K, and an age
of 1.0 Gyrs. The dashed curve is a match to both the
primary and secondary stars for the same metallicity,
and has temperatures of 5427 K and 3239 K for the pri-
mary and secondary stars, and an age of 2.0 Gyrs. The
secondary star is very slightly above these isochrones,
though well within 1-σ, but this desire to have a larger
radius has the effect of “pulling” the isochrone above
the primary star’s position. The third isochrone, shown
as the dotted line, is a match to the primary only, now
with [Fe/H]=0.0. Its age is 1.25 Gyrs, and its temper-
atures is 5501 K, a better match than the [Fe/H]=0.09
case. However, while its mass and radius are an excellent
match to the primary, it under-predicts the radius of the
secondary. This might be a manifestation of the com-
mon problem of low-mass stars being too large and too
cool compared to stellar models (see e.g. Torres 2013).
Additional exploration of isochrones for a spread of met-
alicities showed that ages up to 2.5 Gyrs can reasonably
match the observations. We also compared Yonsei-Yale
isochrones (Yi et al. 2001) with the primary star’s ob-
served mass, radius, and temperature, and found essen-
tially the same results. To summarize, we can well-match
the characteristics of the two stars with isochrones of age
1.0-2.5 Gyrs.
The modulation in the light curve caused by starspots
allows the rotation period of the primary star to be mea-
sured. Using the autocorrelation function (ACF) method
of McQuillan et al. (2014), the rotation period is 20.31
± 0.47 d. We also visually inspected and computed the
ACF for individual Quarters to be sure that the true pe-
riod was not half or twice this value. In comparison, the
orbital period is 27.32 d, and the pseudosynchronous ro-
tation period (Hut 1981, 1982) for the mild eccentricity
of the orbit e=0.051, is 26.90 d. Thus the star’s rotation
is not close to being synchronized with its orbit, though
this is not unexpected given the relatively large orbital
period. Because the spin should synchronize much sooner
than the orbits should circularize (at least in a 2-body
system), the system is likely to have been born with a low
eccentricity. The predicted Vrot sin i using the measured
spin period and stellar radius, and assuming the spin in-
clination is aligned with the binary orbit inclination, is
2.08 km s−1
. This is in agreement with the observed low
projected rotation velocity of the star 1.9 ± 1.0 km s−1
.
Walkowics & Basri (2013) report an age of 2.31 Gyrs
for KIC 9632895, based on their measured rotation pe-
riod of 19.98 d which was determined via a Lomb-
Scargle periodogram. Using our ACF-derived rotation
period and the B-V color index (corrected for redden-
ing), we used five different gyrochronology relations and
found age estimates spanning 2.11 to 2.87 Gyrs (Barnes
2007, Mamajek & Hillenbrand 2008, Meibom et al. 2009,
Barnes 2010, and Epstein & Pinsonneault 2014). These
ages are on the high end of the nominal isochrone age
range, but they should be regarded more as upper limits
because the star may have been influenced by tidal inter-
actions in the binary, which are very slowly driving the
spin period to match the binary orbital period of 27.32
d. Thus the gyrochronology age estimates are in fairly
good agreement with our isochrone age estimate.
Finally, the observed ∼0.22% rms fluctuations in
the light curve is slightly smaller than the solar value
(∼0.3%), suggesting an older, rather than younger, age.
The Ca II H & K lines were not within the wavelength
range of the HET spectra, and were too faint in the Tull
spectra, so they could not be used as an activity or age
indicator. The lack of any emission cores and the lack
of the lithium 6708 ˚A absorption line rules out a very
young age.
The ability to precisely measure the stellar masses and
radii, especially for the low mass secondary star, and the
mass ratio of M2/M1 = 0.208 ± 0.003, make the binary
worthy of a more thorough investigation in its own right.
4.2. The Planet KIC 9632895 b
While the radius of KIC 9632895 b is well determined
at 6.17 ± 0.04 R⊕, we cannot reliably estimate its mass
since it has no measurable effect on the binary during the
course of our observations. If the planet was sufficiently
massive, it would cause periodic changes in the binary
eclipse times (ETVs) on roughly half the orbital period of
the planet. And if the planet’s orbit was not coplanar, it
would cause a precession of the binary orbit (though mea-
surable only if the binary orbit had nonzero eccentricity).
This precession would be most readily detectable via a
difference in the orbital periods of the primary and sec-
ondary stars, i.e., a divergence in the common-period
O − C diagram. Finally, a periodic change in the orbital
inclination of the binary could lead to slight changes in
the primary eclipse depth. As none of these are seen in
the Kepler photometry, we are only able to estimate an
upper limit on the mass, via the following ways. First,
the photodynamical model fits place a 1-σ value of ∼16
M⊕. Second, we can attempt to match the observed
ETVs, both in their point-to-point fluctuations and in
the long-term divergence between primary and secondary
periods. However, there is little correlation between the
observed primary eclipse timings and the expected ETV
signal that would be induced by a planet of any mass.
Nor is there any measurable difference in period (mainly
because of the noisy secondary star eclipse times). These
lead to a best-fit mass near zero. The observed 1-σ upper
limit on the difference in primary and secondary eclipse
periods is 1.7 s, which leads to an upper mass estimate
of ∼ 30 M⊕, but with a large uncertainty of ∼ ±100 M⊕.
Finally, for completeness, a limit based on the light-travel
time effect with a phase consistent with the orbit of the
planet gives a weak upper limit of ∼ 17 MJup.
We can compare the above mass estimates/limits to
the empirically expected mass, based on the radius of
the planet. Several mass-radius relations have been pub-
lished: Lissauer et al. (2011), Kane & Gelino (2012),
Enoch et al. (2012), Weiss et al. (2013), Wu & Lith-
8. 8
wick (2013), and Weiss & Marcy (2014). Assuming that
these relations are applicable to circumbinary planets,
the mass and radius pairs that fall within the range of va-
lidity of these relations span ∼ 17–43 M⊕. These masses
are larger than what the ELC model or ETV analysis
prefers, though not inconsistent with the upper limits.
Given the systematic uncertainties in the empirical re-
lations, the agreement is reasonably good. Taking 32
M⊕ as a 2-σ upper mass estimate, the mean density is
then smaller than 0.75 g cm3
with 95% confidence. If
the mass is truly lower than 16 M⊕, then the density is
< 0.38g cm3
and KIC 9632895 is an unusual low-mass
and low-density planet.
4.3. Orbital Dynamics
The photodynamical model predicts the planet’s (sky-
projected) inclination oscillates with a 102.8 year period,
which is also the precession period of the planet’s orbit.
For the best-fit solution, the planet’s inclination varies by
4.575 deg. Conservation of angular momentum requires
the binary’s orbital plane to also oscillate, but with a
miniscule ∼ 10−5
deg amplitude – which is not surprising
as the best-fit planet mass is near zero. Fig. 8 illustrates
the geometry of the binary and a spatial view of the rapid
precession of the planet’s orbit.
As a consequence of this changing inclination of the
planet’s orbit, the impact parameter of the planet will
vary by a large amount; over a fairly short timescale the
planet prcessed from non-transiting to transiting, then
will become non-transiting again. In these Kepler data
the planet transits 50% of the time: three non-transits
followed by three transits. However, this was very for-
tuitous — due to the relatively large mutual inclination
between the orbital planes, the majority of the time the
planet does not transit the star at conjunction. Transits
only occur when the impact parameter, defined as the
minimum projected distance of the planet’s limb from
the center of the primary star during conjunction, rela-
tive to the radius of the primary, is less than unity. This
occurs only 8.4% ± 0.2% of the time. In Fig. 9 we show
explicitly the sinusoidal oscillation of the planet’s orbital
inclination, along with the mutual inclination, and the
evolution of the planet’s impact parameter across the
primary star. An interesting and important implication
is that because of observational duration limitations, for
every system like KIC 9632895 we see, there are ∼12
similar systems that we do not see. The importance of
binary-induced planetary orbital precession in determin-
ing circumbinary transit probabilities was foreseen by the
prescient Schneider (1994).
In addition to the observed transit times, durations,
and depths, Table 5 includes predicted near-future tran-
sit times. The near-future timescale is by necessity —
we predict the transits will stop being visible after 2015
July and not return until 2066.
4.4. Stability and Long Term Evolution
Following Dvorak (1986) and Holman & Wiegert
(1999), we calculated the orbital period where the
planet is highly susceptible to a dynamical instability.
With its orbital period 8.80 times the binary period,
KIC 9632895 b is comfortably above the critical period
for circumbinary instability: Pp/Pcrit = 2.41. Unlike
previous Kepler circumbinary planets, KIC 9632895 b is
not skirting on the edge of the instability. Note: We have
found an error in previously reported values for P/Pcrit
for Kepler 34, 35 (Welsh et al. 2012) and 38 (Orosz et al.
2012b). The reported values, 1.21, 1.24, and 1.42 should
be 1.49, 1.34, and 1.30.
The above analysis suggests that the orbit of
KIC 9632895 b is dynamically stable. However, it is im-
portant to note that this critical stability limit was de-
rived assuming the planet has negligible mass compared
to the binary, and is initially on a circular and copla-
nar orbit. The perturbing effect of the planet on the
dynamics of the binary is ignored. So to truly examine
the long-term stability of the orbit of the planet, one has
to integrate the equations of motion of the three-body
system.
We first investigated the stability of the planet by ap-
plying the MEGNO (Mean Exponential Growth factor
of Nearby Orbits) criterion (see Cincotta & Simo 1999,
2000; Go´zdziewski, et al. 2001; Go´zdziewski & Maciejew-
ski 2001; and Hinse et al. 2010). MEGNO is used to de-
termine general regions of dynamical instability, chaotic
zones, and the locations of orbital resonances. Fig. 10
shows the result of computing the MEGNO3
factor over
a grid of the test planet’s initial semi-major axis and
eccentricity. All other orbital parameters are fixed and
taken as the best-fit ELC values in Table 3. Each of
the 240,000 pixels in the map was integrated for ∼18,500
binary periods (500,000 days). The color coding corre-
sponds to the degree to which the orbit of the test planet
is chaotic (yellow) or quasi-periodic (blue). The location
of the planet’s best-fit osculating Keplerian semi-major
axis and eccentricity (from Table 3) is marked with the
black dot. The MEGNO map shows that the planet or-
bit resides in a region of phase space that is not chaotic
for at least the ∼1370 yr duration of the MEGNO in-
tegration. Note that the yellow instability gaps dipping
into the blue region of the map correspond to n:1 mean-
motion resonances between the planet and the binary
orbit. These resonances play an important role in estab-
lishing the final orbit of the planet during its migration
from outer regions of the disk where it is presumably
formed (Kley & Haghighipour 2014).
To better determine the long-term stability of the
planet, we integrated the orbits of the three-body system
for 100 kyrs (365 million days). The results are shown
in Fig. 11. As expected, the variations in the semi-major
axis and eccentricity of the planet are negligibly small
over the course of the integration, demonstrating that
the orbit of the planet is stable on at least this timescale.
The long-term integrations also show that the mutual in-
clination between the planet and the binary is not caused
by the gravitational interactions, i.e., it is a “free” incli-
nation that is presumably primordial (tides are unable to
significantly modify this inclination). Similarly, as men-
tioned before, the eccentricity of the binary is also likely
primordial. The planet’s eccentricity is dominated by
the forcing of the binary, but there is a free eccentricity
component as well (see Leung & Lee 2012).
3 The computation of MEGNO maps made
use of the MECHANIC software available at
https://github.com/mslonina/Mechanic; see Slonina, Go´zdziewski
& Migaszewski 2015).
9. 9
4.5. A Planet in the Habitable Zone
The habitable zone (HZ) around a binary star is nei-
ther spherical nor fixed – it revolves with the binary.
Nevertheless, time-averaged approximations are useful
for a preliminary investigation of the orbit of the planet
with respect to its location in the habitable zone. In this
approximation, we use the time-averaged distance of bod-
ies in elliptical Keplerian orbits (see Williams 2003). We
also ignored the secondary star’s flux contribution since
it emits less than ∼0.3% of the light in the Kepler band-
pass. Using Teff of 5527 K for the primary star and Teff of
3309 K for the secondary star, the secondary emits 0.85%
of the bolometric luminosity. Assuming a Bond albedo
of 0.34, appropriate for both the gas giant planets in our
Solar System and for the Earth itself, and assuming re-
emission over a full sphere, we find the planet’s Teq =
247 K and the time-averaged insolation to be S = 0.94
in Sun-Earth units. This is within the conservative HZ
limits defined by the runaway and maximum greenhouse
criteria for the inner and outer boundaries. Even at the
most extreme ranges of star-planet separation due to the
eccentricity, Teq only varies between 237 K and 259 K.
We also calculated the properties of the HZ using the
more detailed methodology presented by Haghighipour
& Kaltenegger (2013) and the Multiple Star HZ calcu-
lator4
(Mueller & Haghighipour 2014). The results are
presented in Fig. 12, where the dark green region cor-
responds to the narrow (conservative) HZ and the light
green corresponds to the nominal (extended) HZ as de-
fined by Kopparapu et al. (2013a,b, with coefficients up-
dated on-line in 2014). The dashed circle represent the
dynamical stability limit.
We then computed the instantaneous insolation using
our photodynamical model, which gave a mean insola-
tion over one full precession cycle of 0.958 S. Fig. 13
shows this varying insolation incident upon the planet
from both stars as a function of time. The most obvious
variation is due to the orbital motion of the primary star.
Superposed on this is the variation due to the eccentric
orbit of the planet. Finally, on a ∼103 year timescale,
the effects of the oscillation of the mutual inclination are
apparent. The overall fluctuation in insolation is 8.2%
(rms) about the mean. Interestingly, from the perspec-
tive of the planet, not every stellar conjunction is seen
as an eclipse. This is due to the mutual inclination of
the orbits. Only when the planet crosses the plane of
the binary (i.e. near the nodal points) will an eclipse be
seen from the planet. Since the ratio of orbital periods is
8.8025, and there are two nodal crossings per orbit, the
eclipses are visible every ∼4.4 binary periods, but varies
slightly with the oscillation of the mutual inclination.
Although KIC 9632895 b is a 6-R⊕size planet and it-
self unlikely to harbor conditions suitable for life, such
a planet could host a large moon capable of sustaining
life. Since no evidence for such a moon is apparent we
do not pursue this further,except to mention that in gen-
eral, the effect noted by Mason et al. (2013) should be
considered: in a binary, tides can significantly change
the spin evolution – and thus the activity – of the stars,
rendering the system more, or less, habitable depending
on the specifics of the binary.
4 http://astro.twam.info/hz/
Other than the outer planets of the Kepler-47 system,
all transiting Kepler circumbinary planets fall within
a factor of 2 of the critical radius for instability. As
remarked upon in Orosz et al. (2012b), whether this
is a selection effect or not, the observed close-tO −
Critical orbits have an interesting consequence: the
Kepler circumbinary planets tend to lie close to their
HZ. Both Kepler-16 b and Kepler-47 c are in the HZ.
KIC 9632895 b now joins this group of HZ circumbinary
planets, and currently 3 out of 10 Kepler circumbinary
systems reside in the HZ. Thus, although difficult to de-
tect because of their large variations in transit timing
and duration, the search for smaller Earth-size planets
in circumbinary environments is a particularly exciting
endeavor.
We thank Amy McQuillan of Tel Aviv University for
assistance with the measurement of the ACF, and Jus-
tice Bruursema for assisting with the WIYN observa-
tions. W.F.W. thanks the Institute for Astronomy and
the NASA Astrobiology Institute at the University of
Hawaii-Manoa for their support and kind hospitality
during his sabbatical visit when part of this project
was carried out. W.F.W. and J.A.O. gratefully ac-
knowledge support from the National Science Foundation
via grant AST-1109928, and from NASA’s Kepler Par-
ticipating Scientist Program (NNX12AD23G) and Ori-
gins of Solar Systems Program (NNX13AI76G). T.C.H.
gratefully acknowledges financial support from the Ko-
rea Research Council for Fundamenta Science and Tech-
nology (KRCF) through the Young Research Scientist
Fellowship Program and financial support from KASI
(Korea Astronomy and Space Science Institute) grant
number 2013-9-400-0/2014-1-400-06. Numerical com-
putations were partly carried out using the SFI/HEA
Irish Centre for High-End Computing (ICHEC) and the
KMTNet computing cluster at the Korea Astronomy
and Space Science Institute. Astronomical research at
the Armagh Observatory is funded by the Northern Ire-
land Department of Culture, Arts and Leisure (DCAL).
N.H. acknowledges support from the NASA ADAP grant
NNX13AF20G, NASA Origins grant NNX12AQ62G,
Astrobiology Institute under Cooperative Agreement
NNA09DA77 at the Institute for Astronomy, University
of Hawaii, and HST grant HST-GO-12548.06-A. Sup-
port for program HST-GO-12548.06-A was provided by
NASA through a grant from the Space Telescope Science
Institute, which is operated by the Association of Uni-
versities for Research in Astronomy, Incorporated, under
NASA contract NAS5-26555. T.M. gratefully acknowl-
edges support of from the European Research Council
under the EU’s Seventh Framework Programme (ERC
Grant Agreement No. 291352). B.Q. gratefully acknowl-
edges the support of the NASA Postdoctoral Program.
J.H.S. acknowledges the support from NASA’s Kepler
Participating Scientist Program (NNX12AD23G). The
authors acknowledge the outstanding work of David
Ciardi (NExScI/Caltech) in organizing and maintain-
ing the Kepler Community Follow-up Observing Program
(CFOP) website5
. We also thank Phil Lucas for organiz-
ing the UKIRT J-band observations of the Kepler field
5 https://cfop.ipac.caltech.edu/home/
10. 10
available on the CFOP website. This research has made
use of the NASA Exoplanet Archive, which is operated
by the California Institute of Technology, under contract
with the National Aeronautics and Space Administration
under the Exoplanet Exploration Program. Kepler was
competatively selected as the 10th mission of the Dis-
covery Program. Funding for this mission is provided by
NASA, Science Mission Directorate.
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11. 11
Table 1
Radial velocities of KIC 9632895
HJD RV1 uncertainty Telescope
(- 2,455,000) (km s−1) (km s−1)
987.95667 -12.065 0.095 HJST Tull
990.93694 -2.892 0.054 HJST Tull
991.93040 0.151 0.040 HJST Tull
1000.96729 0.525 0.033 HET HRS
1002.97067 -4.559 0.036 HET HRS
1009.94932 -18.663 0.025 HET HRS
1013.95060 -15.701 0.034 HET HRS
1016.93457 -7.233 0.028 HET HRS
1019.94404 1.749 0.028 HET HRS
1022.90513 6.082 0.038 HET HRS
1034.89098 -15.616 0.036 HET HRS
1727.97974a -4.774 0.085 HJST Tull
a The bulk of our analysis was completed before this observation was made, so it was not used. The predicted value from the photodynamical
model for this datum (which is 693 d after the last radial velocity measurement we used) differs by only 0.093 km s−1 (1.1σ) from the
observed value.
Table 2
WIYN/WHIRC Detection Limitsa
∆(mag)
Filter FWHM [ ] 1.5 2.0 2.5 5.0
J 0.87 2.6 3.8 4.1 4.3
H 0.97 2.1 3.3 3.5 3.6
Ks 0.87 2.8 3.2 3.3 3.4
a Tabulated values give the detection limits in relative magnitudes at four radial distances from the source.
12. 12
Table 3
KIC 9632895 System Parametersa
Parameter Best fit Uncertainty Units
Binary
M1 0.934 ± 0.010 M
M2 0.1938 ± 0.0020 M
R1 0.833 ± 0.011 R
R2 0.2143 ± 0.0014 R
orbital period 27.322037 ± 0.000017 days
Tconj -34.574013 ± 0.000060 BJDb
inclination 90.275 ± 0.052 degrees
e sin ω -0.0506 ± 0.0037
e cos ω -0.006338 ± 0.000016
eccentricity 0.0510 ± 0.0037
arg. periastron 262.86 ± 0.48 degrees
semi-major axis 0.18479 ± 0.00066 au
limb darkeningc q11 0.413 ± 0.055
primary q21 0.331 ± 0.041
secondary q12 0.40 ± 0.11
secondary q22 0.37 ± 0.13
T1 5527 ± 100 Kd
T2/T1 0.5987 ± 0.0010 K
T2 3309 ± 100 K
log g1 4.566 ± 0.015 cgs
log g2 5.0630 ± 0.0050 cgs
contamination 0.01 ± 0.02
Planet
Mp 0.1 ± 16.0 M⊕
Rp 6.165 ± 0.035 R⊕
orbital period 240.503 ± 0.053 days
Tconj 68.998 ± 0.054 BJDb
inclination 89.4338 ± 0.0056 degrees
e sin ω -0.00093 ± 0.00020
e cos ω -0.03785 ± 0.0088
eccentricity 0.0379 ± 0.0088
arg. periastron -178.59 ± 0.29 degrees
semi-major axis 0.7877 ± 0.0028 au
nodal longitude Ω 2.138 ± 0.055 degrees
mutual inclination 2.297 ± 0.030 degrees
a The reported Keplerian parameters are the instantaneous (osculating) values at the reference epoch Tref=2,454,964 BJD.
b date with respect to BJD–2,455,000.
c quadratic limb darkening coefficients for the primary and secondary stars, following Kipping (2013)
d spectroscopically determined
13. 13
Table 4
Barycentric Initial Dynamical Parameters in Cartesian Coordinatesa
Parameter Primary Star Secondary Star Planet b
m (M ) 9.337681202794083 × 10−1 1.937952112922161 × 10−1 1.859015330241639 × 10−7
x (au) −9.748504997497649 × 10−3 4.697105974670451 × 10−2 4.127928083325089 × 10−1
y (au) 1.529515890494979 × 10−4 −7.369785770015704 × 10−4 8.613416639983943 × 10−3
z (au) −3.189393768140941 × 10−2 1.536759849360090 × 10−1 −6.871064103438431 × 10−1
vx (au day−1) 6.623637055950572 × 10−3 −3.191484642184871 × 10−2 1.765737347143242 × 10−2
vy (au day−1) 1.002847872768725 × 10−5 −4.832118534066960 × 10−5 7.562722510169518 × 10−4
vz (au day−1) −2.091184985444550 × 10−3 1.007599740591624 × 10−2 9.826469371378278 × 10−3
a Valid at the reference time epoch of 2,454,964.00 BJD (or time = -36.00 if using BJD–2,455,000). The (x,y) axes are in the plane of the sky, and
the z direction points towards the observer.
Table 5
Transits Across the Primary Star
Cycle Observed Transit Model Transit Observed Duration Model Duration Observed Relative Model Relative
Number Timea Time (hours) (hours) Depth Depth
1b · · · 69.261 0 0 0 0
2b · · · 304.781 0 0 0 0
3b · · · 542.223 0 0 0 0
4 781.8239 ± 0.0014 781.8227 5.69 ± 0.17 5.769 0.0042 ± 0.0001 0.0048
5 1019.1749 ± 0.0010 1019.1770 12.50 ± 0.12 12.494 0.0047 ± 0.0001 0.0052
6 1254.7319 ± 0.0007 1254.7312 7.12 ± 0.09 6.978 0.0046 ± 0.0001 0.0051
7c · · · 1494.1848 · · · 7.2365 · · · 0.0055
8c · · · 1732.8717 · · · 8.9134 · · · 0.0051
9c · · · 1967.5163 · · · 9.7495 · · · 0.0054
10c · · · 2206.4545 · · · 3.3775 · · · 0.0030
89d · · · 20973.5 · · · · · · · · · · · ·
a BJD–2,455,000.
b No transit occurred because the impact parameter was greater than unity. The times listed are the computed times of conjunction from the
photodynamical model.
c Only transits #4, 5, and 6 were observed. The predicted times of transit have a precision of <10 minutes.
d The next set of visible transits after the 2015 July 02 UT transit is predicted to start circa 2066 November 18. The prediction is likely good to
∼5 hours.
14. 14
Figure 1. The upper panel displays a one-year long segment of the Kepler KIC 9632895 light curve, and shows the modulations in flux
due to starspots. The four lower panels present examples of a secondary eclipse, a planet transit, and two primary eclipses, respectively, as
seen in short-cadence (SC) data. The vertical (flux) scale is the same for the secondary eclipse and transit, but is different from that of the
pair of primary eclipses. The horizontal (time) scale is the same in each panel, and reveals the much longer duration of the transit compared
to the eclipses. Residuals of the ELC model fit are shown in the bottom panels, normalized to the uncertainty, so this is effectively a χ2
per point. The first primary transit shows a clear deviation in the residuals, due to the secondary star crossing over a starspot.
15. 15
Figure 2. All of the Long Cadence primary eclipses (left) and secondary eclipses (right) are phase-folded and plotted together. The offset
of the center of the secondary eclipse from orbital phase 0.5 is caused by the eccentricity of the binary. A preliminary Keplerian model fit
to the binary is overplotted on the data, and the residuals of the fit are shown in the bottom panel on a vastly enlarged scale. The large
increase in scatter seen in the primary eclipse is due to spot-crossing events (i.e., the secondary covering a starspot on the primary). This
starspot-induced noise creates shifts in the best-fit mid-eclipse times and a bias in the model eclipse depth. For these reasons we do not fit
all the eclipse events, as decribed in the text; the fit shown is not the photodynamical model used to determine the system parameters.
16. 16
0 200 400 600 800 1000 1200 1400
time (BJD-2,455,000)
-300
-200
-100
0
100
200
300
EclipsetimeO-C(s)
Figure 3. Starspot-corrected O − C diagram showing the primary eclipse times (black) and secondary eclipse times (red) with respect
to a common linear ephemeris. No trend or pattern above the noise is evident in either case.
17. 17
Figure 4. Radial velocities of the primary star and the best-fitting ELC model curve, plotted versus time (not folded in phase). Residuals
are shown in the bottom panel.
18. 18
Figure 5. Three primary eclipses (top row) and three secondary eclipses (bottom row) used in the adopted fitting methodology. The
best-fit photodynamical model is overplotted in red. Residuals of the fit are shown in the corresponding bottom panels, in units of
parts-per-thousand.
19. 19
Figure 6. Transit light curves and ELC model fits. The upper panels show the epochs where transits would occur, if the binary and
planet orbits were co-planar. The lack of transits in the data (and in the models) illustrate the time-varying mutual inclination of the
orbits. The lower panels show the three observed transits; the first transit was observed with Long Cadence only. The large variations in
transit duration is clear. Note that the plot windows in the upper panels (1.5 d) are wider than in the lower panels (1.0 d).
20. 20
Figure 7. Mass and radius of the stars in KIC 9632895, along with three Dartmouth isochrones (Dotter et al. 2008), are shown. The
solid curve is the best match to the primary star and has an age of 1.0 Gyr; the dashed curve is the best match to both stars and has an
age of 2.0 Gyr. Both isochrones have [Fe/H]=0.09, which is our best estimate for the metallicity. The dotted isochrone has [Fe/H]=0.00
(1-σ lower than the measured value), and an age of 1.25 Gyrs. Also shown for comparison are masses and radii of all known low mass stars
whose precision is better than 5%. (Note: These isochrones are not necessarily appropriate for the other stars as their ages and metallicities
are generally unknown.) Upper Inset: A zoomed-in view for the secondary star. Lower Inset: Similarly, but for the primary star.
21. 21
Figure 8. Scaled views of the orbital configuration. The upper left panel shows a face-on view, and the lower panel shows the edge-on
view of the system at the first observed transit time (BJD–2,455,000 = 781.82). The upper right panel shows the evolution of the planet’s
orbit from time 6,000 to 10,000 days in BJD–2,455,000. For clarity, the vertical scale is exaggerated by a factor of 8.
22. 22
Figure 9. The upper panel shows the ∼103 year oscillation of the planet’s sky-projected orbital inclination. For comparison, the binary’s
orbital inclination curve is also shown (dashed curve) and appears completely flat on this scale. The red horizontal marker shows the
duration of the Kepler Mission. The middle panel shows the mutual inclination of the orbits. The bottom panel shows the variations in
the impact parameter. Transits occur when the impact parameter is less than unity; this criterion is shown by the horizontal green lines.
In each panel, the vertical lines bracket the times when the planet transits the primary star as viewed from Earth. These transit windows,
half a precession cycle apart, only encompass 8.4% of the cycle.
23. 23
Figure 10. Map of the values of MEGNO over a grid of semi-major axis and eccentricity of the planet, spanning 500,000 days. The color
coding indicates the degree of orbital instability, with yellow corresponding to chaotic orbits and blue depicting quasi-periodic orbits. The
orbit of the planet resides well within a stable region. The vertical line marks the stability limit of Holman & Wiegert (1999) for a zero
eccentricity planet. Note that it has been shifted from 0.437 au to 0.405 au to account for the difference in coordinate systems (primary
centric in Holman & Wiegert to Jacobi coordinates relative to the center of mass of the binary for MEGNO). A planet mass of 16 M⊕ was
used; a map with a planet mass of zero shows no difference.
24. 24
Figure 11. The 100 kyr evolution of the planet and binary orbits. From top to bottom the panels show the time evolution of the
semi-major axes and eccentricities of the planet (black) and binary (red), the relative orbital inclination and the relative argument of
pericenter, the relative longitude of the ascending node, and the sine versus cosine components of the iΩ vector. For this last panel, the
scale in i cos Ω is ten times smaller than in i sin Ω. These figures illustrate that no secular trend is present, implying that the orbit of the
planet is stable for long times.
25. 25
−1.5 −1.0 −0.5 0.0 0.5 1.0 1.5
Distance [AU]
−1.5
−1.0
−0.5
0.0
0.5
1.0
1.5
Distance[AU]
Figure 12. Face-on view of the KIC 9632895 system, showing the planet’s orbit relative to the habitable zone. The center of the figure is
at the binary center of mass, and the configuration corresponds to the reference epoch, with the direction of the line-of-sight from the Earth
shown by the arrow. The dashed red circle represents the boundary of stability for planetary orbits. The dark green region corresponds to
the narrow (conservative) HZ and the light green corresponds to the nominal (extended) HZ as defined by Kopparapu et al (2013a,b). The
orbit of the planet is shown in white. While the planet is likely a gas giant and not habitable, its orbit with respect to the HZ is of interest.
An animation of the time-variation of the HZ due to the motion of the binary can be found at the electronic supplementary material and
at the website http://astro.twam.info/hz-ptype/.
26. 26
Figure 13. Sum of the fluxes (insolation) from the primary and secondary star incident at the top of KIC 9632895 b’s atmosphere. The
contribution from the secondary star is so small that it is almost negligible, so it is not shown. The horizontal dashed green lines are
the conservative boundaries of the habitable zone: the “moist greenhouse” (inner edge of HZ) and “maximum greenhouse” (outer HZ) as
defined by Kopparapu et al. (2013a,b). Left panel: The insolation variations on short timescale, spanning exactly three planet orbits. The
27-d orbit of the binary is superimposed on the 240-d modulation due to the planet’s eccentricity. The small, sharp downward spikes every
∼4th binary orbit are due to the stellar eclipses as seen from the planet. Right panel: The longer term variations over a span of 100,000 d
(∼274 years or ∼416 orbits of the planet). The ∼103-year planet precession is responsible for the sinusoidal envelope of the insolation.