This document summarizes the discovery of a fourth planet orbiting the red dwarf star GJ 581. The planet, called GJ 581e, has a minimum mass of 1.9 Earth masses and orbits with a period of 3.15 days, making it the innermost planet in the system. Updated radial velocity measurements also allowed the researchers to correct the orbital period of the outermost planet GJ 581d, determining it to be 66.8 days rather than the previously reported 83 days. This revised period places GJ 581d within the star's habitable zone. The researchers conclude the GJ 581 system has 4 planets, with the detection of GJ 581e being the lowest mass exoplanet
This document summarizes an 8-year survey using the HARPS spectrograph to detect super-Earth and Neptune-mass planets around solar-type stars. Over 50% of solar-type stars were found to harbor at least one planet within 100 days. The mass distribution of super-Earths and Neptune-mass planets increases sharply from 30-15 Earth masses. Most of these planets belong to multi-planetary systems and have orbital eccentricities under 0.45. In contrast, giant planets are more common around metal-rich stars and can have eccentricities over 0.9. The precision of HARPS enables detection of planets in the habitable zones of solar-type stars.
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.
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.
A terrestrial planet_candidate_in_a_temperate_orbit_around_proxima_centauriSérgio Sacani
At a distance of 1.295 parsecs,1 the red-dwarf Proxima Centauri (α Centauri C, GL 551,
HIP 70890, or simply Proxima) is the Sun’s closest stellar neighbour and one of the best studied
low-mass stars. It has an effective temperature of only 3050 K, a luminosity of 0.1 per
cent solar, a measured radius of 0.14 R⊙
2 and a mass of about 12 per cent the mass of the
Sun. Although Proxima is considered a moderately active star, its rotation period is 83
days,3 and its quiescent activity levels and X-ray luminosity4 are comparable to the Sun’s. New
observations reveal the presence of a small planet orbiting Proxima with a minimum mass of
1.3 Earth masses and an orbital period of 11.2 days. Its orbital semi-major axis is 0.05 AU,
with an equilibrium temperature in the range where water could be liquid on its surface.5
Radial velocity monitoring has found the signature of a Msin i = 1:3 M planet located within the Habitable Zone of Proxima
Centauri, the Sun’s closest neighbor (Anglada-Escudé et al. 2016). Despite a hotter past and an active host star the planet Proxima b
could have retained enough volatiles to sustain surface habitability (Ribas et al. 2016). Here we use a 3D Global Climate Model (GCM)
to simulate Proxima b’s atmosphere and water cycle for its two likely rotation modes (the 1:1 and 3:2 spin-orbit resonances) while
varying the unconstrained surface water inventory and atmospheric greenhouse eect (represented here with a CO2-N2 atmosphere.)
We find that a broad range of atmospheric compositions can allow surface liquid water. On a tidally-locked planet with a surface water
inventory larger than 0.6 Earth ocean, liquid water is always present (assuming 1 bar of N2), at least in the substellar region. Liquid
water covers the whole planet for CO2 partial pressures & 1 bar. For smaller water inventories, water can be trapped on the night side,
forming either glaciers or lakes, depending on the amount of greenhouse gases. With a non-synchronous rotation, a minimum CO2
pressure of 10 mbar (assuming 1 bar of N2) is required to avoid falling into a completely frozen snowball state if water is abundant.
If the planet is dryer, 0.5 bar of CO2 would suce to prevent the trapping of any arbitrary small water inventory into polar ice
caps. More generally, any low-obliquity planet within the classical habitable zone of its star should be in one of the climate regimes
discussed here.
We use our GCM to produce reflection/emission spectra and phase curves for the dierent rotations and surface volatile inventories.
We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular
separation of 7=D at 1 m (with the E-ELT) and a contrast of 10 7. The magnitude of the planet will allow for high-resolution
spectroscopy and the search for molecular signatures, including H2O, O2, and CO2.
The observation of thermal phase curves, although challenging, can be attempted with JWST, thanks to a contrast of 210 5 at 10 m.
Proxima b will also be an exceptional target for future IR interferometers. Within a decade it will be possible to image Proxima b and
possibly determine whether this exoplanet’s surface is habitable.
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...Sérgio Sacani
Proxima b is a planet with a minimum mass of 1.3 M⊕ orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass,
active star and the Sun’s closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b
and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet
and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time
evolution of the star’s spectrum, which is essential for modeling the flux received over Proxima b’s lifetime. We also show that Proxima
b’s obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet’s eccentricity and
level of triaxiality. Next we consider the evolution of Proxima b’s water inventory. We use our spectral energy distribution to compute
the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find
that Proxima b is likely to have lost less than an Earth ocean’s worth of hydrogen (EOH) before it reached the HZ 100–200 Myr after
its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We
conclude that Proxima b is a viable candidate habitable planet.
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.
This document summarizes an 8-year survey using the HARPS spectrograph to detect super-Earth and Neptune-mass planets around solar-type stars. Over 50% of solar-type stars were found to harbor at least one planet within 100 days. The mass distribution of super-Earths and Neptune-mass planets increases sharply from 30-15 Earth masses. Most of these planets belong to multi-planetary systems and have orbital eccentricities under 0.45. In contrast, giant planets are more common around metal-rich stars and can have eccentricities over 0.9. The precision of HARPS enables detection of planets in the habitable zones of solar-type stars.
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.
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.
A terrestrial planet_candidate_in_a_temperate_orbit_around_proxima_centauriSérgio Sacani
At a distance of 1.295 parsecs,1 the red-dwarf Proxima Centauri (α Centauri C, GL 551,
HIP 70890, or simply Proxima) is the Sun’s closest stellar neighbour and one of the best studied
low-mass stars. It has an effective temperature of only 3050 K, a luminosity of 0.1 per
cent solar, a measured radius of 0.14 R⊙
2 and a mass of about 12 per cent the mass of the
Sun. Although Proxima is considered a moderately active star, its rotation period is 83
days,3 and its quiescent activity levels and X-ray luminosity4 are comparable to the Sun’s. New
observations reveal the presence of a small planet orbiting Proxima with a minimum mass of
1.3 Earth masses and an orbital period of 11.2 days. Its orbital semi-major axis is 0.05 AU,
with an equilibrium temperature in the range where water could be liquid on its surface.5
Radial velocity monitoring has found the signature of a Msin i = 1:3 M planet located within the Habitable Zone of Proxima
Centauri, the Sun’s closest neighbor (Anglada-Escudé et al. 2016). Despite a hotter past and an active host star the planet Proxima b
could have retained enough volatiles to sustain surface habitability (Ribas et al. 2016). Here we use a 3D Global Climate Model (GCM)
to simulate Proxima b’s atmosphere and water cycle for its two likely rotation modes (the 1:1 and 3:2 spin-orbit resonances) while
varying the unconstrained surface water inventory and atmospheric greenhouse eect (represented here with a CO2-N2 atmosphere.)
We find that a broad range of atmospheric compositions can allow surface liquid water. On a tidally-locked planet with a surface water
inventory larger than 0.6 Earth ocean, liquid water is always present (assuming 1 bar of N2), at least in the substellar region. Liquid
water covers the whole planet for CO2 partial pressures & 1 bar. For smaller water inventories, water can be trapped on the night side,
forming either glaciers or lakes, depending on the amount of greenhouse gases. With a non-synchronous rotation, a minimum CO2
pressure of 10 mbar (assuming 1 bar of N2) is required to avoid falling into a completely frozen snowball state if water is abundant.
If the planet is dryer, 0.5 bar of CO2 would suce to prevent the trapping of any arbitrary small water inventory into polar ice
caps. More generally, any low-obliquity planet within the classical habitable zone of its star should be in one of the climate regimes
discussed here.
We use our GCM to produce reflection/emission spectra and phase curves for the dierent rotations and surface volatile inventories.
We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular
separation of 7=D at 1 m (with the E-ELT) and a contrast of 10 7. The magnitude of the planet will allow for high-resolution
spectroscopy and the search for molecular signatures, including H2O, O2, and CO2.
The observation of thermal phase curves, although challenging, can be attempted with JWST, thanks to a contrast of 210 5 at 10 m.
Proxima b will also be an exceptional target for future IR interferometers. Within a decade it will be possible to image Proxima b and
possibly determine whether this exoplanet’s surface is habitable.
The habitability of Proxima Centauri b - I. Irradiation, rotation and volatil...Sérgio Sacani
Proxima b is a planet with a minimum mass of 1.3 M⊕ orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass,
active star and the Sun’s closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b
and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet
and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time
evolution of the star’s spectrum, which is essential for modeling the flux received over Proxima b’s lifetime. We also show that Proxima
b’s obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet’s eccentricity and
level of triaxiality. Next we consider the evolution of Proxima b’s water inventory. We use our spectral energy distribution to compute
the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find
that Proxima b is likely to have lost less than an Earth ocean’s worth of hydrogen (EOH) before it reached the HZ 100–200 Myr after
its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We
conclude that Proxima b is a viable candidate habitable planet.
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.
This document summarizes the detection of a super-Earth planet orbiting the star GJ 832. Radial velocity data from three telescopes revealed a planet, GJ 832c, with an orbital period of 35.68 days and a minimum mass of 5.4 Earth masses. GJ 832c has a low eccentricity orbit of 0.18 near the inner edge of the star's habitable zone. However, given its large mass, the planet likely has a massive atmosphere that could render it uninhabitable. The GJ 832 system resembles a miniature version of our solar system, with an interior potentially rocky planet and a distant gas giant.
SPECTROSCOPIC CONFIRMATION OF THE EXISTENCE OF LARGE, DIFFUSE GALAXIES IN THE...Sérgio Sacani
We recently identified a population of low surface brightness objects in the field of the z = 0.023 Coma cluster,
using the Dragonfly Telephoto Array. Here we present Keck spectroscopy of one of the largest of these “ultradiffuse
galaxies” (UDGs), confirming that it is a member of the cluster. The galaxy has prominent absorption
features, including the Ca II H+K lines and the G-band, and no detected emission lines. Its radial velocity of
cz=6280±120 km s−1 is within the 1σ velocity dispersion of the Coma cluster. The galaxy has an effective
radius of 4.3 ± 0.3 kpc and a Sérsic index of 0.89 ± 0.06, as measured from Keck imaging. We find no indications
of tidal tails or other distortions, at least out to a radius of ∼2re. We show that UDGs are located in a previously
sparsely populated region of the size—magnitude plane of quiescent stellar systems, as they are ∼6 mag fainter
than normal early-type galaxies of the same size. It appears that the luminosity distribution of large quiescent
galaxies is not continuous, although this could largely be due to selection effects. Dynamical measurements are
needed to determine whether the dark matter halos of UDGs are similar to those of galaxies with the same
luminosity or to those of galaxies with the same size.
Three new circumbinary planets have been discovered orbiting binary star systems, rather than single stars. This establishes a new class of planets and shows that circumbinary planets are not rare, with an estimated frequency of at least 1% for short-period binary systems, implying millions exist in the Milky Way. While the three discovered planets are too hot or cold to support life, circumbinary planets could potentially be habitable.
The long period_galactic_cepheid_rs_puppisSérgio Sacani
This document summarizes an observational study that uses light echoes to determine the geometric distance to the Cepheid variable star RS Puppis. Images of RS Puppis and its surrounding nebula were taken over multiple epochs with the ESO NTT telescope to track the progression of light variations within the nebula. Photometric measurements of the phase lag in several nebula regions were used to derive a geometric distance of 1,992 ± 28 parsecs to RS Puppis, one of the most accurate distances yet measured to a Cepheid variable star.
The document summarizes the first results from an ambitious HARPS program to detect Earth-like planets around nearby solar-type stars using high-precision radial velocity measurements. It reports the discovery of five new low-mass planets around the stars HD 20794, HD 85512, and HD 192310, including a system of three super-Earths and a planet with a mass of 3.6 Earth masses located at the inner edge of the habitable zone. This confirms previous indications that low-mass planets seem to be very frequent around solar-type stars, with an occurrence rate that may be higher than 30%.
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
Predictions of the_atmospheric_composition_of_gj_1132_bSérgio Sacani
GJ 1132 b is a nearby Earth-sized exoplanet transiting an M dwarf, and is amongst the most highly
characterizable small exoplanets currently known. In this paper we study the interaction of a magma
ocean with a water-rich atmosphere on GJ 1132b and determine that it must have begun with more
than 5 wt% initial water in order to still retain a water-based atmosphere. We also determine the
amount of O2
that can build up in the atmosphere as a result of hydrogen dissociation and loss.
We find that the magma ocean absorbs at most ∼ 10% of the O2 produced, whereas more than
90% is lost to space through hydrodynamic drag. The most common outcome for GJ 1132 b from our
simulations is a tenuous atmosphere dominated by O2
, although for very large initial water abundances
atmospheres with several thousands of bars of O2
are possible. A substantial steam envelope would
indicate either the existence of an earlier H2
envelope or low XUV flux over the system’s lifetime. A
steam atmosphere would also imply the continued existence of a magma ocean on GJ 1132 b. Further
modeling is needed to study the evolution of CO2
or N2
-rich atmospheres on GJ 1132 b.
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.
Water vapour absorption_in_the_clear_atmosphere_of_a_neptune_sized_exoplanetSérgio Sacani
This document summarizes research on the transmission spectrum of the exoplanet HAT-P-11b, a Neptune-sized planet. Observations from the Hubble Space Telescope and Spitzer Space Telescope detected water vapor absorption in the planet's atmosphere at a wavelength of 1.4 micrometers. Analysis of the spectrum indicates the atmosphere is predominantly clear down to 1 mbar and has a hydrogen abundance similar to solar values. Atmospheric modeling suggests a metallicity around 190 times that of the Sun's, in agreement with core accretion planet formation theories. This makes HAT-P-11b the smallest exoplanet to date with a detected molecular signature in its atmosphere, providing new insights into the composition and formation of Neptune-sized
Spectral and morphological_analysis_of_the_remnant_of_supernova_1987_a_with_a...Sérgio Sacani
The document provides a spectral and morphological analysis of the remnant of Supernova 1987A using data from the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA images from 94 GHz to 672 GHz reveal non-thermal synchrotron and thermal dust emission components. The analysis shows a decreasing east-west asymmetry with frequency, attributed to shorter synchrotron lifetimes at high frequencies. Across the radio to far-infrared transition, excess emission is seen that could be due to a second synchrotron component, implying a pulsar wind nebula in the remnant interior.
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,
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...Sérgio Sacani
This document discusses observations of six lensed starburst galaxies at redshift ~2.5 using the Atacama Large Millimeter/submillimeter Array (ALMA). The key findings are:
1) ALMA detected emission and absorption lines of the CH+ molecule in the spectra of five out of the six galaxies, indicating dense shocks and highly turbulent reservoirs of cool gas extending over 10 kiloparsecs outside the starburst regions.
2) The broad CH+ emission lines trace shocks moving at ~40 km/s within dense gas, while the absorption lines reveal turbulent reservoirs with velocities of ~400 km/s.
3) The turbulent reservoirs have radii of 10-20 kilopar
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.
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.
A higher efficiency_of_converting_gas_to_stars_push_galaxies_at_z_1_6_well_ab...Sérgio Sacani
Galáxias formando estrelas em taxas extremas a nove bilhões de anos atrás eram mais eficientes do que a média das galáxias atuais, descobriram os pesquisadores.
A maioria das estrelas acredita-se localizam-se na sequência principal onde quanto maior a massa da galáxia, mais eficiente ela é na formação de novas estrelas. Contudo, de vez em quando uma galáxia apresentará uma explosão de novas estrelas que brilham mais do que o resto. Uma colisão entre duas grandes galáxias é normalmente a causa dessas fases de explosões de formação de estrelas, onde o gás frio que reside nas grandes nuvens moleculares torna-se o combustível para sustentar essas altas taxas de formação de estrelas.
A questão que os astrônomos têm feito é se essas explosões de estrelas no início o universo foram o resultado de se ter um suprimento de gás abundante, ou se as galáxias convertiam o gás de maneira mais eficiente.
Um novo estudo, publicado no Astrophysical Journal Letters de 15 de Outubro, liderado por John Silverman, do Kavli Institute for Physics and Mathematics of the Universe, estudou o conteúdo do gás monóxido de carbono (CO) em sete galáxias de explosão de estrelas muito distantes, quando o universo tinha apenas 4 bilhões de anos de vida. Isso foi possível devido a capacidade do Atacama Large Millimiter/Submillimiter Array (ALMA), localizado no platô no topo da montanha no Chile, que trabalha para detectar as ondas eletromagnéticas no comprimento de onda milimétrico (importante para se estudar o gás molecular) e um nível de sensibilidade que só agora começa a ser explorado pelos astrônomos.
Os pesquisadores descobriram que a quantidade de gás CO emitido já tinha diminuído, mesmo apesar da galáxia continuar a formar estrelas em altas taxas. Essas observações são similares àquelas registradas para as galáxias de explosões de estrelas próximas da Terra atualmente, mas a quantidade da depleção de gás não foi tão rápida quanto se esperava. Isso levou os pesquisadores a concluírem que poderia haver um contínuo aumento na eficiência, dependendo em de quanto acima da taxa de se formar estrelas ela está da sequência principal.
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.
This document presents a sample of 151 dwarf galaxies that exhibit optical spectroscopic signatures of accreting massive black holes. The sample was identified by systematically searching ~25,000 emission-line galaxies from the Sloan Digital Sky Survey with stellar masses comparable to or less than the Large Magellanic Cloud. Many of the galaxies show narrow-line signatures of black hole accretion, and some also exhibit broad H-alpha emission, indicating gas orbiting in the deep potential of a massive black hole. This increases the number of known active galaxies in this low stellar mass range by over an order of magnitude. The median stellar mass of the host galaxies is around 108.5 solar masses, around 1-2 magnitudes fainter than previous samples of
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
The nonmagnetic nucleus_of_comet_67_p_churyumov_gerasimenkoSérgio Sacani
Artigo descreve como a sonda Rosetta e o módulo Philae descobriram que o cometa Churyumov-Gerasimenko não é magnetizado, contrariando uma teoria da formação do Sistema Solar.
A 2 4_determination_of_the_local_value_of_the_hubble_constantSérgio Sacani
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to
reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%.
The bulk of this improvement comes from new, near-infrared observations of Cepheid
variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling
the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these
in turn leverage the magnitude-redshift relation based on 300 SNe Ia at z <0.15. All
19 hosts as well as the megamaser system NGC4258 have been observed with WFC3
in the optical and near-infrared, thus nullifying cross-instrument zeropoint errors in the
relative distance estimates from Cepheids. Other noteworthy improvements include a
33% reduction in the systematic uncertainty in the maser distance to NGC4258, a larger
sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to
the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of
Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW)
Cepheids.
The document discusses the early expansion and formation of the universe according to the Big Bang theory and cosmic inflation theory. It describes how, nearly 14 billion years ago, the universe began as an infinitely small, dense, and hot ball that rapidly expanded and cooled over time, giving rise to space, matter, and energy. It also explains how cosmic inflation theory proposes that the early universe expanded exponentially faster than the speed of light for a fraction of a second, growing trillions of times larger and helping to explain the large-scale structure of the present-day universe.
Microsoft Word The Project, Islam And Sciencekkkseld
This document discusses the relationship between Islam and science. It begins by describing how knowledge is viewed in the Quran and by the Prophet Muhammad, noting many verses that urge Muslims to actively pursue knowledge. It then contrasts the Islamic perspective, which sees religion and science as compatible, to the historical Western perspective where religion and science conflicted. The document goes on to provide examples of scientific phenomena described in the Quran. It aims to show how Islam inspired scientific pursuit and that some Quranic verses reflected scientific facts not known at the time.
This document summarizes the detection of a super-Earth planet orbiting the star GJ 832. Radial velocity data from three telescopes revealed a planet, GJ 832c, with an orbital period of 35.68 days and a minimum mass of 5.4 Earth masses. GJ 832c has a low eccentricity orbit of 0.18 near the inner edge of the star's habitable zone. However, given its large mass, the planet likely has a massive atmosphere that could render it uninhabitable. The GJ 832 system resembles a miniature version of our solar system, with an interior potentially rocky planet and a distant gas giant.
SPECTROSCOPIC CONFIRMATION OF THE EXISTENCE OF LARGE, DIFFUSE GALAXIES IN THE...Sérgio Sacani
We recently identified a population of low surface brightness objects in the field of the z = 0.023 Coma cluster,
using the Dragonfly Telephoto Array. Here we present Keck spectroscopy of one of the largest of these “ultradiffuse
galaxies” (UDGs), confirming that it is a member of the cluster. The galaxy has prominent absorption
features, including the Ca II H+K lines and the G-band, and no detected emission lines. Its radial velocity of
cz=6280±120 km s−1 is within the 1σ velocity dispersion of the Coma cluster. The galaxy has an effective
radius of 4.3 ± 0.3 kpc and a Sérsic index of 0.89 ± 0.06, as measured from Keck imaging. We find no indications
of tidal tails or other distortions, at least out to a radius of ∼2re. We show that UDGs are located in a previously
sparsely populated region of the size—magnitude plane of quiescent stellar systems, as they are ∼6 mag fainter
than normal early-type galaxies of the same size. It appears that the luminosity distribution of large quiescent
galaxies is not continuous, although this could largely be due to selection effects. Dynamical measurements are
needed to determine whether the dark matter halos of UDGs are similar to those of galaxies with the same
luminosity or to those of galaxies with the same size.
Three new circumbinary planets have been discovered orbiting binary star systems, rather than single stars. This establishes a new class of planets and shows that circumbinary planets are not rare, with an estimated frequency of at least 1% for short-period binary systems, implying millions exist in the Milky Way. While the three discovered planets are too hot or cold to support life, circumbinary planets could potentially be habitable.
The long period_galactic_cepheid_rs_puppisSérgio Sacani
This document summarizes an observational study that uses light echoes to determine the geometric distance to the Cepheid variable star RS Puppis. Images of RS Puppis and its surrounding nebula were taken over multiple epochs with the ESO NTT telescope to track the progression of light variations within the nebula. Photometric measurements of the phase lag in several nebula regions were used to derive a geometric distance of 1,992 ± 28 parsecs to RS Puppis, one of the most accurate distances yet measured to a Cepheid variable star.
The document summarizes the first results from an ambitious HARPS program to detect Earth-like planets around nearby solar-type stars using high-precision radial velocity measurements. It reports the discovery of five new low-mass planets around the stars HD 20794, HD 85512, and HD 192310, including a system of three super-Earths and a planet with a mass of 3.6 Earth masses located at the inner edge of the habitable zone. This confirms previous indications that low-mass planets seem to be very frequent around solar-type stars, with an occurrence rate that may be higher than 30%.
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
Predictions of the_atmospheric_composition_of_gj_1132_bSérgio Sacani
GJ 1132 b is a nearby Earth-sized exoplanet transiting an M dwarf, and is amongst the most highly
characterizable small exoplanets currently known. In this paper we study the interaction of a magma
ocean with a water-rich atmosphere on GJ 1132b and determine that it must have begun with more
than 5 wt% initial water in order to still retain a water-based atmosphere. We also determine the
amount of O2
that can build up in the atmosphere as a result of hydrogen dissociation and loss.
We find that the magma ocean absorbs at most ∼ 10% of the O2 produced, whereas more than
90% is lost to space through hydrodynamic drag. The most common outcome for GJ 1132 b from our
simulations is a tenuous atmosphere dominated by O2
, although for very large initial water abundances
atmospheres with several thousands of bars of O2
are possible. A substantial steam envelope would
indicate either the existence of an earlier H2
envelope or low XUV flux over the system’s lifetime. A
steam atmosphere would also imply the continued existence of a magma ocean on GJ 1132 b. Further
modeling is needed to study the evolution of CO2
or N2
-rich atmospheres on GJ 1132 b.
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.
Water vapour absorption_in_the_clear_atmosphere_of_a_neptune_sized_exoplanetSérgio Sacani
This document summarizes research on the transmission spectrum of the exoplanet HAT-P-11b, a Neptune-sized planet. Observations from the Hubble Space Telescope and Spitzer Space Telescope detected water vapor absorption in the planet's atmosphere at a wavelength of 1.4 micrometers. Analysis of the spectrum indicates the atmosphere is predominantly clear down to 1 mbar and has a hydrogen abundance similar to solar values. Atmospheric modeling suggests a metallicity around 190 times that of the Sun's, in agreement with core accretion planet formation theories. This makes HAT-P-11b the smallest exoplanet to date with a detected molecular signature in its atmosphere, providing new insights into the composition and formation of Neptune-sized
Spectral and morphological_analysis_of_the_remnant_of_supernova_1987_a_with_a...Sérgio Sacani
The document provides a spectral and morphological analysis of the remnant of Supernova 1987A using data from the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA images from 94 GHz to 672 GHz reveal non-thermal synchrotron and thermal dust emission components. The analysis shows a decreasing east-west asymmetry with frequency, attributed to shorter synchrotron lifetimes at high frequencies. Across the radio to far-infrared transition, excess emission is seen that could be due to a second synchrotron component, implying a pulsar wind nebula in the remnant interior.
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,
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...Sérgio Sacani
This document discusses observations of six lensed starburst galaxies at redshift ~2.5 using the Atacama Large Millimeter/submillimeter Array (ALMA). The key findings are:
1) ALMA detected emission and absorption lines of the CH+ molecule in the spectra of five out of the six galaxies, indicating dense shocks and highly turbulent reservoirs of cool gas extending over 10 kiloparsecs outside the starburst regions.
2) The broad CH+ emission lines trace shocks moving at ~40 km/s within dense gas, while the absorption lines reveal turbulent reservoirs with velocities of ~400 km/s.
3) The turbulent reservoirs have radii of 10-20 kilopar
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.
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.
A higher efficiency_of_converting_gas_to_stars_push_galaxies_at_z_1_6_well_ab...Sérgio Sacani
Galáxias formando estrelas em taxas extremas a nove bilhões de anos atrás eram mais eficientes do que a média das galáxias atuais, descobriram os pesquisadores.
A maioria das estrelas acredita-se localizam-se na sequência principal onde quanto maior a massa da galáxia, mais eficiente ela é na formação de novas estrelas. Contudo, de vez em quando uma galáxia apresentará uma explosão de novas estrelas que brilham mais do que o resto. Uma colisão entre duas grandes galáxias é normalmente a causa dessas fases de explosões de formação de estrelas, onde o gás frio que reside nas grandes nuvens moleculares torna-se o combustível para sustentar essas altas taxas de formação de estrelas.
A questão que os astrônomos têm feito é se essas explosões de estrelas no início o universo foram o resultado de se ter um suprimento de gás abundante, ou se as galáxias convertiam o gás de maneira mais eficiente.
Um novo estudo, publicado no Astrophysical Journal Letters de 15 de Outubro, liderado por John Silverman, do Kavli Institute for Physics and Mathematics of the Universe, estudou o conteúdo do gás monóxido de carbono (CO) em sete galáxias de explosão de estrelas muito distantes, quando o universo tinha apenas 4 bilhões de anos de vida. Isso foi possível devido a capacidade do Atacama Large Millimiter/Submillimiter Array (ALMA), localizado no platô no topo da montanha no Chile, que trabalha para detectar as ondas eletromagnéticas no comprimento de onda milimétrico (importante para se estudar o gás molecular) e um nível de sensibilidade que só agora começa a ser explorado pelos astrônomos.
Os pesquisadores descobriram que a quantidade de gás CO emitido já tinha diminuído, mesmo apesar da galáxia continuar a formar estrelas em altas taxas. Essas observações são similares àquelas registradas para as galáxias de explosões de estrelas próximas da Terra atualmente, mas a quantidade da depleção de gás não foi tão rápida quanto se esperava. Isso levou os pesquisadores a concluírem que poderia haver um contínuo aumento na eficiência, dependendo em de quanto acima da taxa de se formar estrelas ela está da sequência principal.
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.
This document presents a sample of 151 dwarf galaxies that exhibit optical spectroscopic signatures of accreting massive black holes. The sample was identified by systematically searching ~25,000 emission-line galaxies from the Sloan Digital Sky Survey with stellar masses comparable to or less than the Large Magellanic Cloud. Many of the galaxies show narrow-line signatures of black hole accretion, and some also exhibit broad H-alpha emission, indicating gas orbiting in the deep potential of a massive black hole. This increases the number of known active galaxies in this low stellar mass range by over an order of magnitude. The median stellar mass of the host galaxies is around 108.5 solar masses, around 1-2 magnitudes fainter than previous samples of
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
The nonmagnetic nucleus_of_comet_67_p_churyumov_gerasimenkoSérgio Sacani
Artigo descreve como a sonda Rosetta e o módulo Philae descobriram que o cometa Churyumov-Gerasimenko não é magnetizado, contrariando uma teoria da formação do Sistema Solar.
A 2 4_determination_of_the_local_value_of_the_hubble_constantSérgio Sacani
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to
reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%.
The bulk of this improvement comes from new, near-infrared observations of Cepheid
variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling
the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these
in turn leverage the magnitude-redshift relation based on 300 SNe Ia at z <0.15. All
19 hosts as well as the megamaser system NGC4258 have been observed with WFC3
in the optical and near-infrared, thus nullifying cross-instrument zeropoint errors in the
relative distance estimates from Cepheids. Other noteworthy improvements include a
33% reduction in the systematic uncertainty in the maser distance to NGC4258, a larger
sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to
the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of
Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW)
Cepheids.
The document discusses the early expansion and formation of the universe according to the Big Bang theory and cosmic inflation theory. It describes how, nearly 14 billion years ago, the universe began as an infinitely small, dense, and hot ball that rapidly expanded and cooled over time, giving rise to space, matter, and energy. It also explains how cosmic inflation theory proposes that the early universe expanded exponentially faster than the speed of light for a fraction of a second, growing trillions of times larger and helping to explain the large-scale structure of the present-day universe.
Microsoft Word The Project, Islam And Sciencekkkseld
This document discusses the relationship between Islam and science. It begins by describing how knowledge is viewed in the Quran and by the Prophet Muhammad, noting many verses that urge Muslims to actively pursue knowledge. It then contrasts the Islamic perspective, which sees religion and science as compatible, to the historical Western perspective where religion and science conflicted. The document goes on to provide examples of scientific phenomena described in the Quran. It aims to show how Islam inspired scientific pursuit and that some Quranic verses reflected scientific facts not known at the time.
Islam and Science
Language: English | Format: PDF | Pages: 392 | Size: 1 MB
Amongst us, human beings, none is completely devoid of the innate feeling – even from time to time – that there is a Creating God behind this universe. Such a feeling may be frustrating and people may be prevented from responding to it by the teachings they get as a result of their belonging to a particular environment, their indulgence in earthly life and cheap pleasure naturally, the Almighty Creator should differ from us in all respects:
لَيۡسَ كَمِثۡلِهِۦ شَىۡءٌ۬ۖ
“And unto Him the like is not”(Ash-Shûrâ : 11)
Most people could not be easily induced by this sincere feeling of the existence of the Creator to follow the right path leading to Him. Thus, Allâh [God’s name in Islâm] sent Prophets and Messengers – Allâh’s prayer and peace be upon them – with Divine support in the form of miracles suitable to their environment, until the advent of the last of His Messengers,Prophet Muhammad, who emerged after the maturity of the human thinking when the age of science was immanent; Allâh supported him with the Qur’ân to be an Eternal Miracle.
Spermatogenesis and oogenesis both use meiosis to produce gametes. Spermatogenesis occurs in the testes and results in 4 haploid sperm from one diploid germ cell. Oogenesis occurs in the ovaries and results in one haploid egg and 3 polar bodies from the original diploid oocyte. Both processes arrest at different stages of meiosis until fertilization.
This article was published in California Math Council's Communicator magazine in March 08. I always go back to it to refresh ideas on improving student achievement in math. Feel free to share with attribution.
Episode 111 Premium: There is no PMI Project Management MethodologyOSP International LLC
The new PMBOK® Guide 4th Edition will be available on Dec 31 2008. We take this opportunity to talk about one of the bigger misconceptions that people have about the PMBOK® Guide: They think that is is a methodology.
In this regard, you may hear many people say that they are "using the PMI Methodology" on their project or that they have "implemented the PMBOK methodology at work". In this presentation we explain why the PMBOK Guide is not a methodology, but a framework.
This is one of our Premium "Overtime" Episodes, which are normally reserved to the subscribers of the Premium PM Podcast. However, this is also the first of many presentation style episodes that we will publish, so it is made available to everyone, so that you can see what you would receive with your subscription to The Premium PM Podcast.
This document contains a 9 question music magazine questionnaire that asks respondents about their gender, age, occupation, music preferences, magazine reading habits, purchase locations, reasons for purchase, and spending on music magazines. It collects demographic and preference information to understand the music magazine consumer market.
This document provides an outline for Day 30 of a Construction Foundation Course. The day focuses on blueprints, construction math, and tools/equipment. Activities include reviewing blueprints and plumbing/electrical systems, playing construction-themed games, working in stations to develop tool proficiency, and providing a construction recommendation to a hypothetical homeowner. The document lists learning objectives, materials, and a detailed schedule of activities for the full class period from 7:30am to 11:30am.
The document discusses various technologies that can be used to help retain students, including mobile phones, MP3 players, desktop/laptop computers, software, the internet, and web conferencing tools. It emphasizes that an effective technology plan requires support from staff and stakeholders, clear goals, staff training, and identifying ongoing funding. The document also provides examples of how different technologies like podcasting, blogs, and wikis can be used as part of a student retention strategy.
Move Over Plans - Business Continuity Goes Real-timeSeema Sheth-Voss
The document discusses how traditional business continuity planning is no longer effective in today's dynamic environment. It advocates shifting from static planning to "response modeling" using real-time and predictive data. Key attributes of effective continuity plans discussed include plan data that is accessible, contextual and relevant to actual scenarios, and integrated with real-time internal and external data sources to provide situational awareness during incidents. The presentation provides examples from fast fashion retail and outlines challenges and recommendations for getting started with this new approach to continuity planning.
The document provides notice of Goodyear Tire & Rubber Company's 2002 Annual Meeting of Shareholders to be held on April 15, 2002 at 10:00 AM at the company's offices in Akron, Ohio. Shareholders will vote on three items: electing three directors, ratifying the appointment of PricewaterhouseCoopers LLP as independent accountants, and approving the adoption of the 2002 Performance Plan. Shareholders are urged to vote by proxy card, internet, or telephone.
Epic Research is a leading financial services provider with presence in Indian and other global capital markets. Provides Stock Tips, Forex Tips, Commodity Tips, MCX Tips, Equity Tips, Tips, Intraday Tips, NSE Tips, BSE Tips, COMEX Tips, PCG Pack and NCDEX Tips. We provide services in equity, commodity and Forex market.
This document summarizes the community partnerships established at Chesapeake High School (CHS) to enhance their magnet programs in science, technology, engineering, and mathematics (STEM). CHS has partnered with organizations like Lockheed Martin, Northrop Grumman, Johns Hopkins University, and the University of Maryland to provide students with internships, field trips, guest speakers, and teacher externships related to STEM careers. These partnerships help improve STEM education at CHS and increase students' interest in STEM fields.
Olivia, Lucy, Rosie And Derek Music Video Presenatation Thingy Ma Jigguest2c5a24
This music video is for an artist named Olivia and her song about a relationship with Derek. It is filmed in a naturalistic style in the countryside to represent the folk genre. There are many close-ups of Olivia singing and two-shots of her with Derek to illustrate the lyrics and promote the artist. The slow editing and shots represent the calm nature of the song. While there is not a complex narrative, the visuals and music work together to represent the romantic relationship between Olivia and Derek through their interactions in different locations set to the acoustic folk music. The target audience is intended to be female fans of acoustic folk music.
The document discusses an organization's environmental forces and how managers can address them. An organization's environment consists of task environment forces from suppliers, distributors, customers and competitors as well as general forces like economic, technological and demographic trends. Managers must assess the complexity and rate of change in the environment. They can reduce environmental impact through boundary spanning to gather information, scanning the environment, and creating structures to facilitate responsiveness to changes. Managing the organizational environment effectively is key to an organization's success.
A dynamically packed_planetary _system_around_gj667_c_with_three_superearths_...Sérgio Sacani
This document summarizes the discovery of six potentially habitable super-Earth planets orbiting the red dwarf star GJ 667C. Analyzing new Doppler measurements from HARPS and previous data from other spectrographs, the authors detect six planetary candidates with orbital periods of 7, 28, 92, 62, 39, and 260 days. They validate the signals against stellar activity and find the system could be dynamically stable. Three or four of the planets may be located within the star's habitable zone where liquid water could exist, making this one of the first exoplanetary systems discovered with multiple Earth-sized planets in the habitable zone of an M-dwarf star.
An Earth-sized exoplanet with a Mercury-like compositionSérgio Sacani
Earth, Venus, Mars and some extrasolar terrestrial planets1
have a mass and radius that is consistent with a mass fraction
of about 30% metallic core and 70% silicate mantle2
. At the
inner frontier of the Solar System, Mercury has a completely
different composition, with a mass fraction of about 70%
metallic core and 30% silicate mantle3
. Several formation or
evolution scenarios are proposed to explain this metal-rich
composition, such as a giant impact4, mantle evaporation5
or the depletion of silicate at the inner edge of the protoplanetary
disk6. These scenarios are still strongly debated.
Here, we report the discovery of a multiple transiting planetary
system (K2-229) in which the inner planet has a radius
of 1.165 ± 0.066 Earth radii and a mass of 2.59 ± 0.43 Earth
masses. This Earth-sized planet thus has a core-mass fraction
that is compatible with that of Mercury, although it was
expected to be similar to that of Earth based on host-star
chemistry7
. This larger Mercury analogue either formed with
a very peculiar composition or has evolved, for example, by
losing part of its mantle. Further characterization of Mercurylike
exoplanets such as K2-229 b will help to put the detailed
in situ observations of Mercury (with MESSENGER and
BepiColombo8) into the global context of the formation and
evolution of solar and extrasolar terrestrial planets.
The mass of_the_mars_sized_exoplanet_kepler_138_b_from_transit_timingSérgio Sacani
Artigo da revista Nature, descreve o trabalho de astrônomos para medir o tamanho e a massa de um exoplaneta parecido com Marte, além de caracterizar por completo o sistema planetário da estrela Kepler-138.
Final Year Project - Observation and Characterisation of ExoplanetsLucy Stickland
This document summarizes a student report on the observation and characterization of exoplanets. It explores various exoplanet detection techniques, recent increases in Earth-sized planet discoveries, and relationships between stellar and planetary parameters. The student conducted photometry on three known transiting exoplanets - Hat-P-25b, Wasp-43b, and Wasp-2b - using the Sedgwick telescope. Light curves were produced and used to calculate planetary properties. A program called the Exoplanetary Pixelization Transit Model was created and tested to better fit light curves computationally.
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.
TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS...Sérgio Sacani
A large sample of long-period giant planets has been discovered thanks to long-term radial velocity surveys, but only a few
dozen of these planets have a precise radius measurement. Transiting gas giants are crucial targets for the study of atmospheric composition across a wide range of equilibrium temperatures and, more importantly, for shedding light on the formation and evolution
of planetary systems. Indeed, compared to hot Jupiters, the atmospheric properties and orbital parameters of cooler gas giants are
unaltered by intense stellar irradiation and tidal effects.
Aims. We aim to identify long-period planets in the Transiting Exoplanet Survey Satellite (TESS) data as single or duo-transit events.
Our goal is to solve the orbital periods of TESS duo-transit candidates with the use of additional space-based photometric observations
and to collect follow-up spectroscopic observations in order to confirm the planetary nature and measure the mass of the candidates.
Methods. We use the CHaracterising ExOPlanet Satellite (CHEOPS) to observe the highest-probability period aliases in order to discard or confirm a transit event at a given period. Once a period is confirmed, we jointly model the TESS and CHEOPS light curves
along with the radial velocity datasets to measure the orbital parameters of the system and obtain precise mass and radius measurements.
Results. We report the discovery of a long-period transiting Neptune-mass planet orbiting the G7-type star TOI-5678. Our spectroscopic analysis shows that TOI-5678 is a star with a solar metallicity. The TESS light curve of TOI-5678 presents two transit events
separated by almost two years. In addition, CHEOPS observed the target as part of its Guaranteed Time Observation program. After
four non-detections corresponding to possible periods, CHEOPS detected a transit event matching a unique period alias. Follow-up
radial velocity observations were carried out with the ground-based high-resolution spectrographs CORALIE and HARPS. Joint modeling reveals that TOI-5678 hosts a 47.73 day period planet, and we measure an orbital eccentricity consistent with zero at 2σ. The
planet TOI-5678 b has a mass of 20 ± 4 Earth masses (M⊕) and a radius of 4.91 ± 0.08 R⊕. Using interior structure modeling, we find
that TOI-5678 b is composed of a low-mass core surrounded by a large H/He layer with a mass of 3.2
+1.7
−1.3 M⊕.
Conclusions. TOI-5678 b is part of a growing sample of well-characterized transiting gas giants receiving moderate amounts of stellar
insolation (11 S ⊕). Precise density measurement gives us insight into their interior composition, and the objects orbiting bright stars
are suitable targets to study the atmospheric composition of cooler gas giants.
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.
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.
Artigo descreve a descoberta do exoplaneta HATS-6b, um exoplaneta parecido com Saturno, porém pesado como Júpiter ao redor de uma estrela anã-M, o tipo de estrela mais abundante na nossa galáxia.
A candidate super-Earth planet orbiting near the snow line of Barnard’s starSérgio Sacani
This document summarizes the discovery of a candidate super-Earth planet orbiting Barnard's star. Analysis of over 20 years of radial velocity measurements revealed a periodic signal of 233 days, attributed to a planet with a minimum mass of 3.2 Earth masses in a near-circular orbit near the star's snow line. Long-term monitoring also detected a possible second signal with a period over 6,000 days, which could be from a more distant planet or stellar magnetic activity cycle. Independent photometric and spectroscopic monitoring ruled out stellar activity as the cause of the 233-day signal. This candidate planet has one of the lowest minimum masses detected around an M dwarf star.
This document presents an analysis of transit spectroscopy observations of three exoplanets - WASP-12 b, WASP-17 b, and WASP-19 b - using the Wide Field Camera 3 instrument on the Hubble Space Telescope. The observations achieved almost photon-limited precision but uncertainties in the transit depths were increased by the uneven sampling of the light curves. The final transit spectra for all three planets are consistent with the presence of a water absorption feature at 1.4 microns, though the amplitude is smaller than expected from previous Spitzer observations possibly due to hazes. Due to degeneracies between models, the data cannot unambiguously constrain the atmospheric compositions without additional observations.
Refined parameters of the HD 22946 planetary system and the true orbital peri...Sérgio Sacani
Multi-planet systems are important sources of information regarding the evolution of planets. However, the long-period
planets in these systems often escape detection. These objects in particular may retain more of their primordial characteristics compared
to close-in counterparts because of their increased distance from the host star. HD 22946 is a bright (G = 8.13 mag) late F-type star
around which three transiting planets were identified via Transiting Exoplanet Survey Satellite (TESS) photometry, but the true orbital
period of the outermost planet d was unknown until now.
Aims. We aim to use the Characterising Exoplanet Satellite (CHEOPS) space telescope to uncover the true orbital period of HD 22946d
and to refine the orbital and planetary properties of the system, especially the radii of the planets.
Methods. We used the available TESS photometry of HD 22946 and observed several transits of the planets b, c, and d using CHEOPS.
We identified two transits of planet d in the TESS photometry, calculated the most probable period aliases based on these data, and
then scheduled CHEOPS observations. The photometric data were supplemented with ESPRESSO (Echelle SPectrograph for Rocky
Exoplanets and Stable Spectroscopic Observations) radial velocity data. Finally, a combined model was fitted to the entire dataset in
order to obtain final planetary and system parameters.
Results. Based on the combined TESS and CHEOPS observations, we successfully determined the true orbital period of the planet d
to be 47.42489 ± 0.00011 days, and derived precise radii of the planets in the system, namely 1.362 ± 0.040 R⊕, 2.328 ± 0.039 R⊕, and
2.607 ± 0.060 R⊕ for planets b, c, and d, respectively. Due to the low number of radial velocities, we were only able to determine 3σ
upper limits for these respective planet masses, which are 13.71 M⊕, 9.72 M⊕, and 26.57 M⊕. We estimated that another 48 ESPRESSO
radial velocities are needed to measure the predicted masses of all planets in HD 22946. We also derived stellar parameters for the host
star.
Conclusions. Planet c around HD 22946 appears to be a promising target for future atmospheric characterisation via transmission
spectroscopy. We can also conclude that planet d, as a warm sub-Neptune, is very interesting because there are only a few similar
confirmed exoplanets to date. Such objects are worth investigating in the near future, for example in terms of their composition and
internal structure.
This document describes the discovery and characterization of CFBDSIR2149, a late T dwarf found to have an unusually red J-K color and enhanced K-band flux. Spectroscopy with X-Shooter revealed it has a T7 spectral type with low surface gravity features, indicating it is a young substellar object. Comparison to atmospheric models suggests it has a temperature of 650-750K, surface gravity of logg=3.75-4.0, and a mass in the planetary regime of 4-7 Jupiter masses. An analysis of its proper motion finds an 87% probability it is a member of the young AB Doradus moving group, which would make it a free-floating planet with an
Measurement of Jupiter’s asymmetric gravity fieldSérgio Sacani
The gravity harmonics of a fluid, rotating planet can be decomposed
into static components arising from solid-body rotation and dynamic
components arising from flows. In the absence of internal dynamics,
the gravity field is axially and hemispherically symmetric and is
dominated by even zonal gravity harmonics J2n that are approximately
proportional to qn, where q is the ratio between centrifugal
acceleration and gravity at the planet’s equator1
. Any asymmetry in the
gravity field is attributed to differential rotation and deep atmospheric
flows. The odd harmonics, J3, J5, J7, J9 and higher, are a measure of the
depth of the winds in the different zones of the atmosphere2,3
. Here
we report measurements of Jupiter’s gravity harmonics (both even
and odd) through precise Doppler tracking of the Juno spacecraft
in its polar orbit around Jupiter. We find a north–south asymmetry,
which is a signature of atmospheric and interior flows. Analysis of
the harmonics, described in two accompanying papers4,5
, provides
the vertical profile of the winds and precise constraints for the depth
of Jupiter’s dynamical atmosphere.
Magnetic field and_wind_of_kappa_ceti_towards_the_planetary_habitability_of_t...Sérgio Sacani
We report magnetic field measurements for κ
1 Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis
of the magnetic properties determined from spectropolarimetric observations and reconstruct its large-scale surface magnetic
field to derive the magnetic environment, stellar winds and particle flux permeating the interplanetary medium around κ
1 Cet.
Our results show a closer magnetosphere and mass-loss rate of M˙ = 9.7 × 10−13 M yr−1
, i.e., a factor 50 times larger than the
current solar wind mass-loss rate, resulting in a larger interaction via space weather disturbances between the stellar wind and
a hypothetical young-Earth analogue, potentially affecting the planet’s habitability. Interaction of the wind from the young Sun
with the planetary ancient magnetic field may have affected the young Earth and its life conditions.
This study analyzed high-resolution spectra of 125 compact stellar systems (CSSs) in the giant elliptical galaxy NGC 5128 to measure their radial velocities and velocity dispersions. Combining these measurements with structural parameters from imaging, dynamical masses were derived for 112 CSSs, including 89 for the first time. Two distinct sequences were found in the dynamical mass-to-light ratio vs dynamical mass plane, which can be approximated by power laws. The shallower sequence corresponds to bright globular clusters, while the steeper relation appears to be populated by objects requiring significant dark matter such as central black holes or concentrated dark matter. This suggests different formation histories for these CSSs compared to classical globular clusters in NGC 5128 and
Two temperate Earth-mass planets orbiting the nearby star GJ 1002Sérgio Sacani
We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on
the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star
GJ 1002 (relatively faint in the optical, V ∼ 13.8 mag, but brighter in the infrared, J ∼ 8.3 mag), located at 4.84 pc from the Sun.
We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width
half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity.
We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period
of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a
planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from
its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We
find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that
can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ∼ 200 days.
GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star
to the Sun makes the angular sizes of the orbits of both planets (∼ 9.7 mas and ∼ 15.7 mas, respectively) large enough for their atmosphere to be
studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission.
This document summarizes the discovery of an Earth-mass planet orbiting the star Alpha Centauri B. The planet, with a minimum mass similar to Earth, has an orbital period of 3.236 days and is located about 0.04 astronomical units from the star. High-precision radial velocity measurements from the HARPS spectrograph revealed the planet's signal, making it the lightest planet detected around a solar-type star. The discovery demonstrates that current techniques can detect potentially habitable super-Earth planets around Sun-like stars and habitable Earth-like planets around cooler stars.
An Earth-mass planet orbiting a Centauri BCarlos Bella
1) Researchers detected an Earth-mass planet orbiting the star Alpha Centauri B.
2) The planet has a minimum mass similar to Earth and orbits its star with a period of 3.236 days, within 0.04 astronomical units.
3) This makes it the lightest planet detected orbiting a Sun-like star and the closest exoplanet to our solar system found to date.
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
Trusted Execution Environment for Decentralized Process MiningLucaBarbaro3
Presentation of the paper "Trusted Execution Environment for Decentralized Process Mining" given during the CAiSE 2024 Conference in Cyprus on June 7, 2024.
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
We’ll wrap up with a live Q&A session where you can engage with our experts on your specific use cases, and learn more about optimizing your data workflows with AI.
This webinar is ideal for professionals seeking to harness the power of AI within their data management systems while ensuring high levels of customization and security. Whether you're a novice or an expert, gain actionable insights and strategies to elevate your data processes. Join us to see how FME and AI can revolutionize how you work with data!
A Comprehensive Guide to DeFi Development Services in 2024Intelisync
DeFi represents a paradigm shift in the financial industry. Instead of relying on traditional, centralized institutions like banks, DeFi leverages blockchain technology to create a decentralized network of financial services. This means that financial transactions can occur directly between parties, without intermediaries, using smart contracts on platforms like Ethereum.
In 2024, we are witnessing an explosion of new DeFi projects and protocols, each pushing the boundaries of what’s possible in finance.
In summary, DeFi in 2024 is not just a trend; it’s a revolution that democratizes finance, enhances security and transparency, and fosters continuous innovation. As we proceed through this presentation, we'll explore the various components and services of DeFi in detail, shedding light on how they are transforming the financial landscape.
At Intelisync, we specialize in providing comprehensive DeFi development services tailored to meet the unique needs of our clients. From smart contract development to dApp creation and security audits, we ensure that your DeFi project is built with innovation, security, and scalability in mind. Trust Intelisync to guide you through the intricate landscape of decentralized finance and unlock the full potential of blockchain technology.
Ready to take your DeFi project to the next level? Partner with Intelisync for expert DeFi development services today!
5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
It is with great pleasure that we extend to you an invitation to the 5th Power Grid Model Meet-up, scheduled for 6th June 2024. This event will adopt a hybrid format, allowing participants to join us either through an online Mircosoft Teams session or in person at TU/e located at Den Dolech 2, Eindhoven, Netherlands. The meet-up will be hosted by Eindhoven University of Technology (TU/e), a research university specializing in engineering science & technology.
Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
-Insightful presentations covering two practical applications of the Power Grid Model.
-An update on the latest advancements in Power Grid -Model technology during the first and second quarters of 2024.
-An interactive brainstorming session to discuss and propose new feature requests.
-An opportunity to connect with fellow Power Grid Model enthusiasts and users.
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
Discover the seamless integration of RPA (Robotic Process Automation), COMPOSER, and APM with AWS IDP enhanced with Slack notifications. Explore how these technologies converge to streamline workflows, optimize performance, and ensure secure access, all while leveraging the power of AWS IDP and real-time communication via Slack notifications.
In the realm of cybersecurity, offensive security practices act as a critical shield. By simulating real-world attacks in a controlled environment, these techniques expose vulnerabilities before malicious actors can exploit them. This proactive approach allows manufacturers to identify and fix weaknesses, significantly enhancing system security.
This presentation delves into the development of a system designed to mimic Galileo's Open Service signal using software-defined radio (SDR) technology. We'll begin with a foundational overview of both Global Navigation Satellite Systems (GNSS) and the intricacies of digital signal processing.
The presentation culminates in a live demonstration. We'll showcase the manipulation of Galileo's Open Service pilot signal, simulating an attack on various software and hardware systems. This practical demonstration serves to highlight the potential consequences of unaddressed vulnerabilities, emphasizing the importance of offensive security practices in safeguarding critical infrastructure.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
Best 20 SEO Techniques To Improve Website Visibility In SERPPixlogix Infotech
Boost your website's visibility with proven SEO techniques! Our latest blog dives into essential strategies to enhance your online presence, increase traffic, and rank higher on search engines. From keyword optimization to quality content creation, learn how to make your site stand out in the crowded digital landscape. Discover actionable tips and expert insights to elevate your SEO game.
Freshworks Rethinks NoSQL for Rapid Scaling & Cost-EfficiencyScyllaDB
Freshworks creates AI-boosted business software that helps employees work more efficiently and effectively. Managing data across multiple RDBMS and NoSQL databases was already a challenge at their current scale. To prepare for 10X growth, they knew it was time to rethink their database strategy. Learn how they architected a solution that would simplify scaling while keeping costs under control.
Dandelion Hashtable: beyond billion requests per second on a commodity serverAntonios Katsarakis
This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
Dandelion Hashtable: beyond billion requests per second on a commodity server
Gl581 Preprint
1. c ESO 2009
Astronomy & Astrophysics manuscript no. GJ581
April 21, 2009
The HARPS search for southern extra-solar planets
XVIII. An Earth-mass planet in the GJ 581 planetary system
M. Mayor1 , X. Bonfils2,3 , T. Forveille2 , X. Delfosse2 , S. Udry1 , J.-L. Bertaux4 , H. Beust2 , F. Bouchy5 , C. Lovis1 ,
F. Pepe1 , C. Perrier2 , D. Queloz1 , and N. C. Santos1,6
1
Observatoire de Gen` ve, Universit´ de Gen` ve, 51 ch. des Maillettes, CH-1290 Sauverny, Switzerland e-mail:
e e e
michel.mayor@obs.unige.ch
2
Laboratoire d’Astrophysique, Observatoire de Grenoble, Universit´ J. Fourier, Uni. J. Fourier, CNRS (UMR5571), BP 53, F-38041
e
Grenoble, Cedex 9, France
3
Centro de Astronomia e Astrof´sica da Universidade de Lisboa, Observat´ rio Astron´ mico de Lisboa, Tapada da Ajuda, 1349-018
ı o o
Lisboa, Portugal
4
Service d’A´ ronomie du CNRS, BP 3, 91371 Verri` res-le-Buisson, France
e e
5
Institut d’Astrophysique de Paris, CNRS, Universit´ Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France
e
6
Centro de Astrof´sica, Universidade do Porto, Rua das Estrelas, P4150-762 Porto, Portugal
ı
Received / Accepted
ABSTRACT
The GJ 581 planetary system was already known to harbour three planets, including two presumably rocky planets which straddle its
habitable zone. We report here the detection of an additional planet – GJ 581e – with a minimum mass of 1.9 M⊕ . With a period of
3.15 days, it is the innermost planet of the system and has a ∼5% transit probability.
We also correct our previous confusion of the orbital period of GJ 581d (the outermost planet) with a one-year alias, thanks to
an extended time span and many more measurements. The revised period is 66.8 days, and locates the semi-major axis inside the
habitable zone of the low mass star.
The dynamical stability of the 4-planet system imposes an upper bound on the orbital plane inclination. The planets cannot be more
massive than approximately 1.6 times their minimum mass.
Key words. stars: individual: GJ 581 – stars: planetary systems – stars: late-type – technique: radial-velocity
1. Introduction et al. 2007), GJ 176 (Forveille et al. 2008), and here a fourth
planet in the GJ 581 system. These 6 planets all have mini-
HARPS is a vacuum spectrograph designed to measure precise mum masses under approximately 15 Earth-masses, and repre-
radial velocities, with the specific goal of searching for exo- sent approximately half of the known inventory of planets orbit-
planets in the Southern hemisphere Mayor et al. (2003). This ing M stars, and most of its lowest mass members. Besides the
high-resolution Echelle spectrograph (R=115000) is fiber-fed by HARPS planets, this inventory includes three planets around GJ
the ESO 3.6-meter telescope at La Silla Observatory. The con- 876 (Delfosse et al. 1998; Marcy et al. 1998, 2001; Rivera et al.
sortium which built this instrument was granted 500 observing 2005), a single Neptune-mass planet orbiting GJ 436 (Butler
nights over five years to conduct a comprehensive search for ex- et al. 2004), jovian planets bound to GJ 849 (Butler et al. 2006)
oplanets. This large programme addresses several key exoplanet and to GJ 317 (Johnson et al. 2007), and finally a gaseous gi-
questions, including the characterization of very low mass exo- ant planet orbiting GJ 832 (Bailey et al. 2009). Altogether, 8
planets. A significant fraction of the observing time was devoted planetary systems bound to M dwarfs have been identified by
to the study of planets orbiting stars at the bottom of the main the radial velocity technique, for a total of 12 planets. Although
sequence. The M-dwarf sub-programme includes over 100 stars, the statistics are still limited, and come from surveys with differ-
which form a volume-limited sample. ent sensitivities, they indicate that multi-planet systems are com-
Our HARPS search for southern exoplanets orbiting M- mon: the fraction of known multiple systems around M dwarfs
dwarfs is on-going, and has been recently expanded to a larger is already 2/8 (25 %), and it reaches 5/8 (63 %) if one accounts
sample of some 300 low-mass stars. Several planets have al- for systems where a radial velocity drift indicates an additional
ready been detected in the M-dwarf survey: GJ 581 b (Bonfils long-period planet.
et al. 2005b), GJ 581 c and d (Udry et al. 2007), GJ 674 (Bonfils
The different teams which monitor M dwarfs with Doppler
spectroscopy together observe over 300 stars since several years.
Send offprint requests to: M. Mayor
The frequency of planetary systems with at least one identified
Based on observations made with the HARPS instrument on the
gaseous giant planet orbiting these low mass stars is about 1.5%,
ESO 3.6 m telescope under the GTO program ID 072.C-0488 at Cerro
and clearly smaller than the equivalent quantity for K and G
La Silla (Chile). Our radial-velocity, photometric and Ca II H+K in-
dwarfs. Up to periods of several hundred days this comparative
dex time series are available in electronic format the CDS via anony-
deficit of Jupiter-mass planets for M dwarfs is statistically ro-
mous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-
bust (Bonfils et al. 2006; Johnson et al. 2007). Conversely, plan-
strabg.fr/cgi-bin/qcat?J/A+A/
2. 2 M. Mayor et al.: An Earth-type planet in GJ 581 planetary system
ets less massive than ∼25 M⊕ are significantly more frequent 1570 days (4.3 years). In parallel to this extension of the data set,
around M dwarfs (Bonfils et al. 2007). the precision of all measurements, including the previously pub-
The GJ 581 system is of particular interest, as two of its pre- lished ones, has been improved. The reference wavelengths of
viously detected planets are located on the two edges of the hab- the thorium and argon lines of the calibration lamps were re-
itable zone (HZ) of the M3V host star (Selsis et al. 2007; von vised by Lovis & Pepe (2007), and most recently Lovis (2009,
Bloh et al. 2007). Despite the uncertainties on the exact loca- in prep.) implemented a correction for the small effect of Th-Ar
tion of the “liquid water” zone for planets more massive than the calibration lamp aging. The changing internal pressure of aging
Earth, these detections demonstrate that rocky planets in the HZ lamps shifts the wavelength of their atomic transition. The ef-
can be detected by Doppler spectroscopy, for planets orbiting M fect is now corrected down to a level of just a few 0.1 m/s, using
dwarfs. the differential pressure sensitivity of the Argon and Thorium
In this paper we report the detection in the GJ 581 system lines. The combined photon noise and calibration error reult in
a typical overall uncertainty of 1 m s−1 , with a full range of 0.7
of a fourth planet, ’e’, with a minimum mass of 1.94 M⊕ . We
to 2 m s−1 which reflects the weather conditions. The pipeline
also correct the period of the outer planet GJ 581d, and we find
that the revised period locates GJ 581d in the habitable zone. In also shifts the radial velocities to the Solar System Barycentric
section 2 we briefly recall the main characteristics of the host reference frame (Lindegren & Dravins 2003), and automatically
star GJ 581, and of its first three planets. An enlarged set of subtract the RV drift due to perspective acceleration from the
measurements (section 3) allows a reexamination of the struc- proper motion of the star (K¨ rster et al. 2003); 20 cm/s/yr for GJ
u
ture of the GJ581 planetary system, and the discovery of an ad- 581.
ditional very-low-mass planet (section 4). Since Doppler spec-
troscopy, and all the more so for M dwarfs, can be confused
4. GJ 581, a system with four low-mass planets
by stellar surface inhomogeneities, we dedicate section 5 to a
discussion of GJ 581’s magnetic activity. In section 6, dynami- Our preferred method for planet searches in RV data uses a
cal stability considerations allow us to obtain an upper limit to heuristic algorithm, which mixes standard non-linear minimiza-
the planetary masses. To conclude, we briefly discuss how this tions with genetic algorithms. It efficiently explores the large pa-
system meshes up with theoretical predictions, and consider the rameter space of multi-planet systems, and quickly converges
prospects of finding even lower mass planets in the habitable toward the best solution. We tried models composed of zero to
zone of M dwarfs. five planets on Keplerian orbits, and found that the data require
a 4-planets model.
To verify the robustness of that ’black-box’ solution and gain
2. Stellar caracteristics and planetary system
insight on its content, we also performed a step by step peri-
Our report of the first Neptune-mass planet on a 5.36-d orbit odogram analysis. The top panel of Fig. 1 displays the window
around GJ 581 (Bonfils et al. 2005b) extensively describes the function of our RV measurements, and unsurprisingly shows that
properties of the host star. Here we will therefore only summa- the dominant periodicities of our sampling are 1 day and 1 year.
rize those characteristics. The second panel is a floating-mean peridogram (Gilliland &
GJ 581 (HIP 74995, LHS 394) is an M3 dwarf at a distance Baliunas 1987; Zechmeister & K¨ rster 2009) of the RVs. It is
u
to the Sun of 6.3 pc. Its estimated luminosity is only 0.013 L . dominated by a ∼5.36-day periodicity, which corresponds to
Bonfils et al. (2005a) find GJ 581 slightly metal-poor ([Fe/H] = GJ 581b. To estimate the FAP of that peak, we generated vir-
-0.25), in contrast to the supersolar metallicities (Santos et al. tual data sets using boostrap resampling (Press et al. 1992) of
2001, 2004) of most solar-type stars hosting giant planets. All the actual measurements, and examined the peak power in the
indirect tracers (kinematics, stellar rotation, X-ray luminosity, periodogram of each of these virtual datasets. None of 10,000
and chromospheric activity) suggest a minimum age of 2 Gyr. trials had as high a peak as measured for the actual 5.36-day
The HARPS spectra show weak Ca H and K emission, in the signal, which therefore has a FAP below 0.01%. We then ad-
lower quartile of stars with similar spectral types. This very weak justed a Keplerian orbit with that starting period, and exam-
chromospheric emission points towards a long stellar rotation ined the periodogram of the residuals of this 1-planet solution
(Fig. 1, 3rd panel). That second periodogran is dominated by
period.
The first planet was easily detected after only 20 HARPS a peak around ∼ 12.9 day, with a FAP<0.01%, which corre-
observations (Bonfils et al. 2005b), and the periodogram of the sponds to the known planet GJ 581c. We then investigated the
residuals of that first solution hinted at power excess around periodogram of the residuals of the corresponding 2-planets least
13 days. As 30 additional observations were accumulated for a square adjustment. That new periodogram has power excess in
total time span of 1050 days, that coherent signal strengthened the 50-90 days range and around 3.15 days (as well as at 1-
to strong significance, and a third planet appeared, though still day aliases of these periods), both with FAPs<0.01%. The broad
with a significant False Alarm Probability (FAP): GJ 581c had power excess between 50 and 90 days splits into 3 separate peaks
m sin i = 5M⊕ , P = 12.9 days) and a ∼ 0.28% FAP, while the at ∼59, 67 and 82 days, which are 1-year aliases of each other
more distant GJ 581d had m sin i = 7.7M⊕ , P = 83 days, and a (1/67 − 1/365 ∼ 1/82, 1/67 + 1/365 ∼ 1/59, ). In Udry et al.
∼ 3% FAP. (Udry et al. 2007). Udry et al. (2007) therefore ended (2007), we attributed an 82-days period to GJ 581 d. The corre-
on a call for confirmation by additional radial velocity measure- sponding periodogram peak now has markedly less power than
ments, and based on the very-low magnetic activity of GJ 581, the 67-days periodicity, and attempts to adjust orbits with that
suggested that the significant residuals might reflect additional period (as well as with a 59 days period) produced significantly
planets in the system. larger residuals. We conclude that the actual period of GJ 581
d is around 67 days and that we had previously been confused
by a 1-year alias of that period. As we discuss below, the re-
3. A new data set
vised period locates GJ 581 d in the habitable zone of GJ 581.
Following up on that call for more data, we have now recorded a Subtracting the corresponding 3-planet adjustement leaves no
power excess in the 50-90 days range (5th panel), and markedly
total of 119 H measurements of GJ 581, which together span
3. M. Mayor et al.: An Earth-type planet in GJ 581 planetary system 3
1
enhances the 3.15 day peak. The residuals of this 4-planet so-
lution finally display no statistically significant peak (6th panel).
Window
The strongest peak is located close to one year (P ∼ 384 day) 0.5
and has a ∼50% FAP.
Both the heuristic algorithm and the spectral analysis method
find the same 4 coherent signals in our data. Once this best 0
approximate 4-planet solution had been identified, we per-
500
formed a final global least square adjustment, using the iterative
Levenberg-Marquardt algorithm. Since we find insignificant ec-
centricities for planets ’b’ and ’c’, we fixed the eccentricities and 250
longitude of periastron to zero for both planets. Table 1 lists the
resulting orbital elements, and Fig. 2 displays the corresponding
Keplerian orbits. 0
Compared to our Udry et al. (2007) study, we thus add a
100
fourth planet and very significantly revise the characteristics of
the outer planet (GJ 581d), and in particular its period. Planets
b to e have respective minimum masses of m sin i ∼ 15.7, 5.4, 50
7.1 and 1.9 M⊕ . GJ 581e is the lowest mass exoplanet detected
so far around a main sequence star. None of the period ratios
of the system comes close to any integer value, with e.g. Pb /Pe 0
= 1.70, Pc /Pb = 2.4 and Pd /Pc = 5.17. Non-resonant hierarchies
40
have similarly been noticed for all multi-planet systems which
only contain low mass planets, such as HD 40307 (Mayor et al.
Power
2009) and HD 69830 (Lovis et al. 2006). 20
5. Planets rather than spots 0
Coherent Doppler shifts unfortunately do not always correspond 50
to planets. Inhomogeneities of the stellar surface like spots,
plages, flares or convective patterns can break the even distri-
25
bution between the blue- and red-shifted halves of a rotating star
and induce apparent radial velocity shifts. At best, this intro-
duces noise on the RV measurements, which is usually referred
0
to as “jitter”. In some cases the surface pattern can be stable over
long time spans (from days to years), and the “jitter” noise then 10
is correlated. It then does not average out as white noise would,
and instead builds up a coherent signal. That apparent Doppler
5
shift induced can easily happen to mimic a Keplerian orbit (e.g.
Queloz et al. 2001; Bonfils et al. 2007).
M dwarfs notoriously tend to have stronger magnetic activ-
0
ity than solar-like stars, and possible false detections from co-
1 10 100 1000
herent jitter therefore need even closer scrutiny. We have indeed
Period [day]
encountered several such cases in our M star survey, including
GJ 674 (Bonfils et al. 2007) and GJ 176 (Forveille et al. 2008).
Fig. 1. Periodograms of GJ581 radial velocity measurements. Panel
In both cases, photometric monitoring and spectroscopic activ-
1 (top): Window function of the HARPS measurements. Panel 2:
ity diagnostic (measuring the Ca H&K and Hα lines) demon-
Periodogram of the HARPS velocities. The peaks corresponding to
strated that a seeemingly Keplerian signal was in fact due to GJ581b (P=5.36d) and its alias with the sideral day are clearly visible.
spot modulation of the rotational profile. These two examples Panel 3: HARPS velocities corrected from the velocity variation due to
serve as reminders that a periodic Doppler signal does not al- GJ581b. The peak corresponding to GJ581c (P=12.9d) appears. Panel
ways reflect the presence of a planet, and that additional checks 4: Removing the variability due to planets b and c, we can see the peak
are needed to conclude. due to the P=3.15d variability of GJ581e (+ the alias with the a one
sideral day period) as well as the peak at 66d due to GJ581d. Panel 5 :
In our previous papers on the GJ 581 system, we could
Periodogram after removing the effect of planets b, c and d. The peak
exclude any such confusion for the first three planets. The ∼
due to planet e (Mass = 1.9 earth-mass) is evident (+ its alias with the
13m s−1 radial velocity amplitude due to GJ 581 b (P = 5.36
sideral period). Panel 6 (bottom): Removing the velocity wobbles due
day – Bonfils et al. 2005b) is sufficiently large that a spot sig-
to the four planets, the periodogram of the residual velocities shows no
nal of that magnitude would have induced measurable distor-
additional significant peaks.
tions of the rotational profile. The lack of any correlation be-
tween the bisector span (a first order measurement of spectral
lines asymmetry) and the measured RVs, excludes that scenario.
an unprobably low inclination i to be compatible with a 5 days
The strength of the Ca H&K emission lines in addition classi-
rotation period, The additional measurements since Bonfils et al.
fies GJ 581 in the lowest ∼ 5% magnetic activity bin of our M
(2005b) have strengthened those conclusions even further.
dwarfs sample. This implies a much longer rotation period than
the observed 5.4 days, as confirmed by the very low projected In Udry et al. (2007), we used distinct lines of arguments for
rotational velocity v sin i < 1 km s−1 ). That velocity would need the 12.9 and the 83 days (now 67 days) signals. The arguments
4. 4 M. Mayor et al.: An Earth-type planet in GJ 581 planetary system
Table 1. Fitted orbital solution for the GJ 581 planetary system: 4 Keplerians. The model imposes circular orbits for planets GJ 581 b & e, since
the derived eccentricities for a full Keplerian solution are insignificant (see text).
Parameter GJ 581 e GJ 581 b GJ 581 c GJ 581 d
3.14942 ± 0.00045 5.36874 ± 0.00019 12.9292 ± 0.0047 66.80 ± 0.14
[days]
P
0.17 ± 0.07 0.38 ± 0.09
0 (fixed) 0 (fixed)
e
ω -110 ± 25 -33 ± 15
[deg] 0 (fixed) 0 (fixed)
[m s−1 ] 1.85 ± 0.23 12.48 ± 0.23 3.24 ± 0.24 2.63 ± 0.32
K
[km s−1 ] -9.2082 ± 0.0002
V
[10−14 M ]
f (m) 0.21 108.11 4.34 10.05
m2 sin i [M⊕ ] 1.94 15.65 5.36 7.09
[AU] 0.03 0.04 0.07 0.22
a
119
Nmeas
[days] 1570
Span
σ (O-C) [ms−1 ] 1.53
χ2 1.49
red
developed above for GJ 581b hold for the 12.9-day period, which measurements as a function of time (top panel), and the corre-
is also too short to be compatible with the rotation period. They sponding periodogram (lower panel). It suggests long term varia-
also apply for GJ 581e at 3.1 days. An 83 days (or 67 days) tions, over timescales of several thousands days which are much
period, on the other hand, would be perfectly consistent with the too long to be the rotational period. If those variation are real,
rotation period of an M dwarf with the activity level of GJ 581. they would be more likely to reflect an analog of 11 yers so-
For such long periods the bisector span also loses its diagnostic lar magnetic cycle. Magnetic cycles can potentially affect appar-
power, because the rotational profile becomes much too narrow ent stellar velocities, through their impact on stellar convection
to resolve with HARPS. This calls for a different argument, and which can change the balance between ascending (blue-shifted)
we used a relation by Saar & Donahue (1997) to estimate the and receding (red-shifted) material, but we see no evidence for
minimum filling factor of a spot that could produce the observed long-term RV variations. The other significant structure in the
radial velocity signal. That relation, chromospheric signal is a broad power excess between 80 and
120 days, which is much more likely to reflect the rotation pe-
K s ∼ 6.5 × f s0.9 × v sin i [m s−1 ] (1) riod. That peak overlapped our incorrect initial estimate of the
period of GJ 581 d, but as discussed above the photometry limits
connects the semi-amplitude K s of the radial-velocity signal
the amplitude of any velocity signal from spots at that period to
induced by an equatorial spot with its surface filling factor,
at most a quarter of the observed value. The revised period puts
f s %, and the projected rotation velocity, v sin i. It has been vali-
a final nail in the coffin of that concern, since the periodogram
dated in numerous examples, including e.g. GJ 674 and GJ 176.
of the Ca H+K indices has no power excess around 66 days.
Applying that relation to a R = 0.31 R stellar radius, a P = 83
To summarize, none of the 4 periodic signal detected in our
days period and a K ∼ 2.5 m s−1 semi-amplitude readily showed
RV measurements is compatible with rotationasl modulation of
that the GJ 581 d signal would have needed a f s ∼ 2.2% fill-
stellar surface patterns. Four low-mass exoplanets orbiting the
ing factor to be explained by a spot. Such a large spot is firmly
star remain, by far, the most likely interpretation.
excluded by the sub-% photometric stability of GJ 581.
Our revised 66.7 days period for GJ 581 d weakens that ar-
gument slightly, since a shorter period signal can be induced by a
6. Dynamical evolution
smaller spot. The revision however is minor, as the 67-day signal
still requires a f s = 1.7% spot, which is easily excluded by the
We reinvestigate the dynamics of the revised GJ 581 system, us-
improved photometric measurements that have become avail-
ing the same techniques as in Beust et al. (2008, B08). With the
able since Udry et al. (2007). The strongest photometric stability
SyMBA symplectic N-body code (Duncan et al. 1998), we carry
constraint is provided by 6 weeks of continuous monitoring of
5-body integrations over 0.1 Gyr, with a 2 × 10−4 yr timestep.
GJ 581 by the MOST satellite. Preliminary results, presented
Starting from the nominal solutions (Tab.1), which assumes ini-
by J. Matthews at the 2007 Michelson Summer School1 , indi-
tially circular orbits for Gl581e and Gl581b (the two innermost
cate that the peak-to-peak photometric variability during those
planets), we performe thoses integrations for inclinations of 90
6 weeks was less than 5 mmag. The 66.7-day HARPS radial
to 10 degrees, assuming full coplanarity of all orbits.
velocity signal is therefore incompatible with rotational modu-
Figure 4 shows the maximum variations of the semi-major
lation of spots or granulation patches.
axes and eccentricities during those integrations. As in B08, we
Variations of the chromospheric Ca H+K line provide an-
note that the semi-major variations gradually increase as the in-
other diagnostic of magnetic activity, which proved very val-
clination decreases. This is a clear indication that lower inclina-
ubale for GJ 674 (Bonfils et al. 2007). We parametrize this chro-
tions, i.e. higher planetary masses, produce a less stable system.
mospoheric emission by
Compared to our previous study, the addition of GJ 581e drasti-
H+K cally tightens the minimum inclination constraint. That low mass
Index = , (2)
R+B planet has little effect on the stability of the more massive GJ
581b, GJ 581c, and GJ 581d, but for inclinations 5 ≤ i ≤ 30◦ ,
where H (resp. K) is the flux measured in the Ca H (resp. K)
GJ 581e is ejected out of the system on time scales of at most a
line and where R and B measure the flux in pseudo-continuum
few Myrs.
bands on both sides of the lines. Fig. 3 displays our Ca H+K
The nominal integrations assume circular initial orbits for GJ
1
581e and GJ581b. Relaxing this constraint and setting the initial
http://nexsci.caltech.edu/workshop/2007/Matthews.pdf
5. M. Mayor et al.: An Earth-type planet in GJ 581 planetary system 5
Fig. 4. Stability of various configurations of the four-planet Gl 581 system. The left and right panels respectively show the maximum variations,
after ×108 years, of the semi-major axes and of the eccentricities (right plot) as a function of the assumed inclination of the system (i=0 is pole-on).
Each cross represents one simulation. The grey shading for i < 35◦ marks an instable zone where one or more planets were ejected during the
integration.
eccentricity of planet e to 0.1, we found the system even less tected around main sequence stars. Such a low mass is almost
stable: GJ 581e was then ejected for inclinations up to i = 40◦ . certainly rocky, and its equilibrium temperature is too high to
allow a substantial atmosphere.
Unlike most multi-planet radial-velocity systems, the nomi-
nal least square adjustment to the radial velocities is dynamically GJ 581 has the largest number of measurements in our
stable for sufficiently high inclinations (and co-planar orbits). HARPS M-star sample, which evidently help detect such a low
Restricting the solutions to dynamically stable systems only im- mass planet in a four planet system. The detection however does
poses that i > 40◦ and therefore that the mass of each planet be
∼ not stretch the limits of Doppler spectroscopy, and for the same
no more than ∼1.6 times its minimum mass. For GJ 581e, b, c period a planet only half as massive would have been detectable
and d, those upper limits are 3.1, 30.4, 10.4 and 13.8 M⊕ . in our dataset. Our HARPS measurements set an upper limit of
1.2 m/s on the stellar jitter of GJ 581, based on a quadratic sub-
traction of just the mean photon noise from the observed dis-
7. Summary and discussion persion of the radial-velocity residuals to the 4-planet solution.
Some small fraction of this value could still be instrumental, but
The large number of precise HARPS measurements has now re-
a 1.2 m/s “jitter” allows the detection of a 2 M⊕ planet with a 25
vealed four planets in a non resonnant configuration. The false
days orbital period. Such a planet would be earth-type and in the
alarm probablities of all four planetary signals are below 0.01%.
middle of the habitable zone of its M dwarf.
The orbital elements of planets GJ581b (P=5.36d Bonfils et al.
2005a) and GJ581c Udry et al. (P=12.9d 2007) are fully con- The stellar “jitter” has different physical components, with
firmed, and slightly refined. The 82 days Udry et al. (2007) distinct time scales. For more massive stars and shorter integra-
period for GJ 581d, on the other hand, was a one-year alias tion times, acoustic modes represent a major contribution, but
of the true 66.8 days period of that planet. Our extended span the short acoustic timescales in this small star and the 15 min-
and much larger number of measurements correct that confu- utes integration ensure that they have been averaged out to below
sion. Monitoring of the Ca H+K activity indicator over the four a few 0.1 m/s. The 1.2 m/s jitter therefore mostly reflects longer
years of our spectroscopic measurements indicates that the sig- time-scale phenomena, such as granulation noise and changes
nal at 66 days is not the result of the time variable stellar activity. in stellar surface anisotropies during a magnetic cycle. We are
At the present time, based on the well defined radial velocity sig- developing optimized measurement strategies to average out the
nal and the estimation of the possible effect of the stellar activity granulation noise contribution to the stellar jitter, but HARPS al-
(with the constraint of the small observed photometric variabil- ready demonstrates that the global jitter (including instrumental
ity) the presence of the planet with a period of 66.8 days is the errors, but not photon noise) of reasonably chromospherically
most probable interpretation. quiet M dwarfs is at most of the order of 1 m/s.
The new orbital elements derived for the outer planet GJ This new low mass planet adds to the small set of Doppler-
581d correspond to a 0.22 AU semi-major axis. A planet with detected super-Earths, planets with a minimum mass under
an eccentric orbit receives a larger orbit-averaged flux than a 10 M⊕ . This planetary mass domain, as well as the Neptune-
planet on a circular orbit of the same semi-major axis (Williams mass range (<30 M⊕ ) has largely been populated by the HARPS
& Pollard 2002). GJ 581 d receives the same average flux as a surveys. A few statistical properties have already emerged from
planet on a circular orbit at a = 0.20 AU. The Udry et al. (2007) these early discoveries (Mayor & Udry 2008):
orbital elements of GJ 581d, with a 0.25 AU semi-major axis,
located the planet close to the outer edge of the habitable zone,
− The full distribution of planetary masses is bimodal, with
but most likely just slightly outside (e.g. Selsis et al. 2007). The
revised parameters locate GJ 581d firmly in the habitable zone. distinct peaks corresponding to gaseous giants and super-
Thanks to 119 precise radial velocity measurements, we have Earths. Despite the observational bias against low mass plan-
ets, the distribution below ∼30 M⊕ rises towards super-Earth
discovered a fourth planets in the GJ 581 system. Its minimum
mass, m sin i = 1.9M⊕ , is by far the lowest amongst planets de- planets (cf. Fig. 7 Mayor & Udry 2008).
6. 6 M. Mayor et al.: An Earth-type planet in GJ 581 planetary system
1.25
P = 3.15 day ; m sin i = 1.94M⊕
Ca II H+K
1
5
0.75
RV1 [m s−1 ]
0.5
0
3000 3500 4000 4500 5000
Barycentric Julian Date - 2450000.0 [day]
0.5
−5
Power
0.25
P = 5.37 day ; m sin i = 15.7M⊕
20
0
100 101 102 103 104
10
Period [day]
RV2 [m s−1 ]
0 Fig. 3. The Ca H+K index as function of Julian date (upper panel) and
its periodogram (lower panel).
−10
− The majority of super-Earths and Neptunes are found in mul-
tiplanetary systems. 4 the 6 planetary systems with a known
−20
super-Earth, (GJ 876, HD 40307, HD 7924, GJ 176, GJ 581,
P = 12.9 day ; m sin i = 5.4M⊕ HD 181433) have multiple planets. 2 of these 4 multi-planet
systems associate one super-Earth with one or two gaseous
giant planets (GJ 876, HD 181433), and the other 2 have sev-
5
eral low-mass planets on non resonant orbits (HD 40307, GJ
581). GJ 176 and HD 7924 have only one detected planet,
RV3 [m s−1 ]
though they could obviously have more which haven’t been
0 detected yet. Indeed, the periodogram of HD 7924 shows
hints of possible additional planets (Howard et al. 2009).
− Contrary to gaseous giants, low mass planets seem no more
−5 frequent around metal-rich host stars (Udry et al. 2006).
− In a preliminary analysis, we have detected low mass close-
in planets (P< 50d and m sin i < 30M⊕ ) around 30% of the
200 solar-type stars of the HARPS high precision survey
P = 66.8 day ; m sin i = 7.1M⊕
(Lovis et al. 2009).
5 Systems with several low mass close-in planets provide in-
teresting constraints for models of planetary formation. Three
RV4 [m s−1 ]
systems are particularly noteworthy: HD 69830 (3 planets), HD
0 40307 (3 planets) and GJ 581 (4 planets).
Terquem & Papaloizou (2007), for instance, studied the mi-
gration of cores and terrestrial planets induced by their inter-
action with the protoplanetary disk, and suggest that “if hot
−5
super-Earths or Neptunes form by mergers of inwardly migrat-
ing cores, then such planets are most likely not isolated. We
0 0.25 0.5 0.75 1 would expect to always find at least one, more likely a few,
companions on close and often near-commensurable orbits”.
φ
10 The high observed fraction of multi-planet systems matches that
prediction, but the observed periods are quite far from near-
commensurability.
5
Raymond et al. (2008) discuss observable consequences of
O−C [m s−1 ]
planet formation models in systems with close-in terrestrial plan-
ets, and specifically address the case of GJ 581. In addition to
0
system architecture, they consider information from planet com-
position, which unfortunately is unavailable for the GJ 581 sys-
−5 tem. These authors find two formation mechanisms consistent
with the available data: in situ formation, and formation at a
larger distance followed by type I migration. In situ formation
−10
however would require a massive disk, 17-50 times above the
53000 53500 54000 54500 55000
minimum-mass disk. Type I migration from a larger distance, on
Julian date −2,400,000.0 [day]
the other hand, is expected to leave the close-in low mass planets
Fig. 2. Radial velocity curves for planets e, b, c and d, from top to
bottom. Tthe lowest panel displays the residual to the four-planets kep-
lerian fit.
7. M. Mayor et al.: An Earth-type planet in GJ 581 planetary system 7
in a MMR (mean motion resonance), at odds with the character- Rivera, E. J., Lissauer, J. J., Butler, R. P., et al. 2005, ApJ, 634, 625
Saar, S. H. & Donahue, R. A. 1997, ApJ, 485, 319
istics of the GJ 581 system.
Santos, N. C., Israelian, G., & Mayor, M. 2001, A&A, 373, 1019
Kennedy & Kenyon (2008) study hot super-Earths formation Santos, N. C., Israelian, G., & Mayor, M. 2004, A&A, 415, 1153
as a function of stellar mass and suggest that, with migration, Selsis, F., Kasting, J. F., Levrard, B., et al. 2007, A&A, 476, 1373
short period low-mass planets are most likely to form around Terquem, C. & Papaloizou, J. C. B. 2007, ApJ, 654, 1110
low-mass stars. Above approximately 1 solar-mass, the mini- Udry, S., Bonfils, X., Delfosse, X., et al. 2007, A&A, 469, L43
Udry, S., Mayor, M., Benz, W., et al. 2006, A&A, 447, 361
mum protoplanet mass for migration to close-in orbits is above
von Bloh, W., Bounama, C., Cuntz, M., & Franck, S. 2007, A&A, 476, 1365
10 Earth-masses and no hot super-Earths can form. Our searches Williams, D. M. & Pollard, D. 2002, International Journal of Astrobiology, 1, 61
for low mass planets with the HARPS spectrograph will test that Zechmeister, M. & K¨ rster, M. 2009, ArXiv e-prints
u
prediction.
Zhou et al. 2009 (in prep.) study the birth of multiple super-
Earths through sequential accretion. Focusing on the formation
of the HD 40307 triple super-Earths system, they found evi-
dence that massive embryos can assemble in a gaseous proto-
stellar disk. The final states of their numerical simulations favor
models with a reduction factor of ten for type I migration. These
simulations quite succesfully reproduce the global structure of
the triple super-Earth system, including non-resonant period ra-
tios.
Our HARPS surveys search for low-mass close-in planets
around stars with masses from 0.3 to over 1 solar-mass. The nu-
merous multiplanetary systems which they will detect will pro-
vide stimulating constraints for formation scenarios.
Acknowledgements. The authors thank the observers of the other HARPS
GTO sub-programmes who helped measure GJ 581. We are grateful to the
staff of La Silla Observatory for their contribution to the success of the
HARPS project. We wish to thank the Programme National de Plan´ tologie
e
(INSU-PNP) and the Swiss National Science Foundation for their continuous
support of our planet-search programs. XB acknowledges support from the
¸˜
Fundacao para a Ciˆ ncia e a Tecnologia (Portugal) in the form of a fellow-
e
ship (reference SFRH/BPD/21710/2005) and a program (reference PTDC/CTE-
AST/72685/2006), as well from the Gulbenkian Foundation for funding through
¸˜
the “Programa de Est´mulo Investigacao”. NCS would like to thank the support
ı
¸˜
from Fundacao para a Ciˆ ncia e a Tecnologia, Portugal, in the form of a grant
e
(references POCI/CTE-AST/56453/2004 and PPCDT/CTE-AST/56453/2004),
and through program Ciˆ ncia 2007 (C2007-CAUP-FCT/136/2006).
e
References
Bailey, J., Butler, R. P., Tinney, C. G., et al. 2009, ApJ, 690, 743
Beust, H., Bonfils, X., Delfosse, X., & Udry, S. 2008, A&A, 479, 277
Bonfils, X., Delfosse, X., Udry, S., Forveille, T., & Naef, D. 2006, in Tenth
Anniversary of 51 Peg-b: Status of and prospects for hot Jupiter studies, ed.
L. Arnold, F. Bouchy, & C. Moutou, 111–118
Bonfils, X., Delfosse, X., Udry, S., et al. 2005a, A&A, 442, 635
Bonfils, X., Forveille, T., Delfosse, X., et al. 2005b, A&A, 443, L15
Bonfils, X., Mayor, M., Delfosse, X., et al. 2007, A&A, 474, 293
Butler, R. P., Johnson, J. A., & Marcy, G. W. 2006, astro-ph/10179
Butler, R. P., Vogt, S. S., Marcy, G. W., et al. 2004, ApJ, 617, 580
Delfosse, X., Forveille, T., Mayor, M., et al. 1998, A&A, 338, L67
Duncan, M. J., Levison, H. F., & Lee, M. H. 1998, AJ, 116, 2067
Forveille, T., Bonfils, X., Delfosse, X., et al. 2008, ArXiv e-prints
Gilliland, R. L. & Baliunas, S. L. 1987, ApJ, 314, 766
Howard, A. W., Johnson, J. A., Marcy, G. W., et al. 2009, ArXiv e-prints
Johnson, J. A., Butler, R. P., Marcy, G. W., et al. 2007, ApJ, 670, 833
Kennedy, G. M. & Kenyon, S. J. 2008, ApJ, 682, 1264
K¨ rster, M., Endl, M., Rouesnel, F., et al. 2003, A&A, 403, 1077
u
Lindegren, L. & Dravins, D. 2003, A&A, 401, 1185
Lovis, C., Mayor, M., Pepe, F., et al. 2006, Nature, 441, 305
Lovis, C. & Pepe, F. 2007, A&A, 468, 1115
Marcy, G. W., Butler, R. P., Fischer, D., et al. 2001, ApJ, 556, 296
Marcy, G. W., Butler, R. P., Vogt, S. S., Fischer, D., & Lissauer, J. J. 1998, ApJ,
505, L147
Mayor, M., Pepe, F., Queloz, D., et al. 2003, The Messenger, 114, 20
Mayor, M. & Udry, S. 2008, Physica Scripta Volume T, 130, 014010
Mayor, M., Udry, S., Lovis, C., et al. 2009, A&A, 493, 639
Press, W. H., Teukolsky, S. A., Vetterling, W. T., & Flannery, B. P. 1992,
Numerical recipes in C. The art of scientific computing (Cambridge:
University Press, —c1992, 2nd ed.)
Queloz, D., Henry, G. W., Sivan, J. P., et al. 2001, A&A, 379, 279
Raymond, S. N., Barnes, R., & Mandell, A. M. 2008, MNRAS, 384, 663