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The researchers investigate atmospheric evaporation of four super-Earth exoplanets - HD 97658 b, GJ 1214 b, 55 Cnc e, and CoRoT-7 b - using X-ray observations of the host stars to estimate planetary mass loss over time. They find the planets receiving the greatest amount of high-energy stellar radiation, like CoRoT-7 b, have likely experienced significant atmospheric mass loss and may be sculpted into lower mass, denser remnant cores. The estimated current mass loss rates and total integrated mass lost over the star's lifetime support this hypothesis.
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of gas, liberating enormous amounts of energy that might
regulate star formation on galaxy-wide scales1–3
. The nature of
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largely unconstrained by observations, and is instead routinely
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“shadows” cast by molecular clouds as they move inward at ∼ 300
km s−1
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remain poorly understood. Observations of eccentric systems provide key insights on those topics as they can
illuminate how a planet’s atmosphere responds to changes in incident flux. We report here the analysis of multi-day
multi-channel photometry of the eccentric (e ~ 0.93) hot Jupiter HD80606b obtained with the Spitzer Space
Telescope. The planet’s extreme eccentricity combined with the long coverage and exquisite precision of new
periastron-passage observations allow us to break the degeneracy between the radiative and dynamical timescales
of HD80606b’s atmosphere and constrain its global thermal response. Our analysis reveals that the atmospheric
layers probed heat rapidly (∼4 hr radiative timescale) from<500 to 1400 K as they absorb ~20% of the incoming
stellar flux during the periastron passage, while the planet’s rotation period is 93 35
85
-
+ hr, which exceeds the predicted
pseudo-synchronous period (40 hr).
Key words: methods: numerical – planet–star interactions – planets and satellites: atmospheres – planets and
satellites: dynamical evolution and stability – planets and satellites: individual (HD 80606 b) – techniques:
photometric
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largely unconstrained by observations, and is instead routinely
simplified as a smooth, spherical inflow of very hot gas
in accordance with the Bondi solution4
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km s−1
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The document summarizes satellite remote sensing data related to clouds, aerosols, and atmospheric composition from NASA satellites including Terra, Aqua, ICESat, and SeaWiFS. It describes algorithms and products for deriving cloud and aerosol optical properties including optical thickness, effective radius, and phase from multi-spectral sensor measurements. Examples of monthly mean cloud properties, aerosol optical thickness, and case studies of dust plumes over Africa are shown.
Superflares in G, K and M Type Dwarfs from Kepler Observations
We study the occurrence of superflares in G, K and M type dwarfs from lightcurves obtained by the Kepler mission. From that set 380 stars are detected with flares above 10^34 erg with 1690 such events. Various stellar parameters are considered here to find what circumstances are favorable for the occurrence of superflares. With decreasing effective temperature the flaring rate increases, as well as with an increase in the star's rotation rate. Star spots, which are a proxy for the magnetic field strength and dynamo activity, are seen more frequently in flaring stars and cover a larger proportion of the star's. surface. Using Ohmic dissipation as proxy for flare events, we perform simulations for a turbulent dynamo and find an increase of Ohmic dissipation as the dynamo number increases, in line with the observations.
Final Poster
1. The document describes a new method for selecting dust-reddened quasars that are radio quiet using data from the Wide-Field Infrared Survey Explorer (WISE). The selection process involves identifying bright objects in WISE that have color ratios consistent with quasars, and then visually inspecting archival images to identify point sources.
2. This new selection method identified 12 potential radio-quiet, dust-reddened quasars. Optical and infrared spectra were obtained for these objects using the Keck and NASA IRTF telescopes. Redshifts were calculated by identifying emission lines and their wavelengths.
3. BPT diagrams using emission line ratios identified 5 of the 8 objects as quasars, providing a sample of
Cosmological parameter
This document summarizes cosmological parameters measured from galaxy surveys. It discusses:
1) Direct measurements of the Hubble constant from the Hubble Space Telescope and Planck, finding values of 72-74 km/s/Mpc and 67.3 km/s/Mpc respectively.
2) Supernova surveys finding evidence for an accelerating universe with matter density of ~30% and dark energy density of ~70%.
3) Measurements of cosmic microwave background from COBE, WMAP and Planck, determining ages and densities of the universe.
4) Galaxy clustering surveys like SDSS detecting baryon acoustic oscillations to measure dark energy properties.
Astronomy - State of the Art - Telescopes
Telescopes help us learn about the universe by collecting more light than the human eye and seeing more detail. Larger telescopes collect more light and see sharper images, but the atmosphere limits ground-based telescope resolution. Telescope size has grown exponentially over time. Adaptive optics and interferometry allow telescopes to approach the theoretical resolution limit. While space telescopes avoid many atmospheric limitations, they are much more expensive to build and operate. The Hubble Space Telescope has revolutionized astronomy through high-quality images across the electromagnetic spectrum.
Chile
This document provides an overview of cosmology and discusses several open questions. It describes the expansion of the universe and the Friedmann equation. The universe began over 13 billion years ago and has expanded since. While the standard cosmological model fits existing data, questions remain about what constitutes dark matter and dark energy, as well as what happened before the hot big bang, such as during inflation.
Pwr10Show
This document explores scales of size from the very large to the very small. It begins with the largest known structures in the universe being over 100 billion light years across and progresses down to the smallest subatomic particles that are mere femtometers in size. In between, it discusses distances such as the size of Earth, our solar system, galaxy, and provides comparisons to everyday objects to help conceptualize different scales. The goal is to convey how vastly large yet minutely small the range is between the greatest and least in our universe.
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...
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
02 distances and scaling
The document discusses different units used to measure large distances in space, including astronomical units (AU) which is the distance between the Earth and Sun, and light years which is the distance light travels in one year. It provides examples of converting between AU, kilometers, and light years using the distances of various objects from the Sun like Earth, Alpha Centauri, and Pluto. Tables are included showing celestial bodies and their distances from the Sun in both AU and kilometers.
FDL 2017 Lunar Water and Volatiles
This document describes research on using deep learning to automatically detect craters on the lunar surface. Key points:
- Craters near the lunar poles may contain water ice in permanently shadowed regions but current maps have issues that make planning missions difficult.
- The researchers created a new dataset of over 28,000 labeled images to train a convolutional neural network (CNN) crater detector.
- The CNN achieved 98% accuracy, a major improvement over previous methods, and was much faster than manual detection. This tool will help create better maps to plan future missions to study lunar volatiles like water ice.
Is there an_exoplanet_in_the_solar_system
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
Prebiotic chemicals in_the_coma_of_comet_67_p_churyumov_gerasimenko
The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are
key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it
is generally believed that these are formed by aqueous alterations. In the collector aerogel and foil samples of the
Stardust mission after the flyby at comet Wild 2, the simplest form of amino acids, glycine, has been found
together with precursor molecules methylamine and ethylamine. Because of contamination issues of the samples,
a cometary origin was deduced from the 13C isotopic signature. We report the presence of volatile glycine
accompanied by methylamine and ethylamine in the coma of 67P/Churyumov-Gerasimenko measured by
the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer, confirming the
Stardust results. Together with the detection of phosphorus and a multitude of organic molecules, this result
demonstrates that comets could have played a crucial role in the emergence of life on Earth.
TNO poster final
The document discusses two proposed missions to minor planets past Neptune. Mission 1 would launch in 2038 and arrive at Haumea in 2055, traveling 16.45 years. Mission 2 would launch in 2027 and first arrive at Huya in 2047 after 19.86 years, then continue on to Quaoar, arriving in 2054 after a total flight time of 26.74 years. Both missions would utilize a Jupiter flyby for assistance and carry scientific instruments to analyze the composition and properties of the target objects.
Spectroscopic confirmation of_the_existence_of_large_diffuse_galaxies_in_the_...
Artigo descreve como uma equipe de astrônomos usou o telescópio Keck I para confirmar a existência das Galáxias Ultra Difusas, ou UDGs no Universo.
What's hot (20)
Magnetic interaction of_a_super_cme_with_the_earths_magnetosphere_scenario_fo...
Magnetic interaction of_a_super_cme_with_the_earths_magnetosphere_scenario_fo...
Cold clumpy accretion_toward_an_active_supermasive_black_hole
Cold clumpy accretion_toward_an_active_supermasive_black_hole
Distances luminosities and_temperatures_of_the_coldest_known_substelar_objects
Distances luminosities and_temperatures_of_the_coldest_known_substelar_objects
The canarias einstein_ring_a_newly_discovered_optical_einstein_ring
The canarias einstein_ring_a_newly_discovered_optical_einstein_ring
Superflares in G, K and M Type Dwarfs from Kepler Observations
Superflares in G, K and M Type Dwarfs from Kepler Observations
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...
Prebiotic chemicals in_the_coma_of_comet_67_p_churyumov_gerasimenko
Prebiotic chemicals in_the_coma_of_comet_67_p_churyumov_gerasimenko
Spectroscopic confirmation of_the_existence_of_large_diffuse_galaxies_in_the_...
Spectroscopic confirmation of_the_existence_of_large_diffuse_galaxies_in_the_...
Similar to Spencer_AAS
A rock composition_for_earth_sized_exoplanets
1) Researchers measured the mass of Kepler-78b, an Earth-sized exoplanet orbiting its host star every 8.5 hours, to be 1.69 ± 0.41 M⊕ using Doppler spectroscopy of the star's radial velocity variations.
2) Given the planet's radius of 1.20 ± 0.09 R⊕, its mean density of 5.3 ± 1.8 g/cm3 is similar to Earth's, suggesting a rocky composition of iron and rock.
3) Kepler-78b is the smallest exoplanet yet characterized with both an accurate mass and radius measurement, extending measurements of planetary composition into the size range of Earth and Venus.
Direct Measure of Radiative And Dynamical Properties Of An Exoplanet Atmosphere
Two decades after the discovery of 51Pegb, the formation processes and atmospheres of short-period gas giants
remain poorly understood. Observations of eccentric systems provide key insights on those topics as they can
illuminate how a planet’s atmosphere responds to changes in incident flux. We report here the analysis of multi-day
multi-channel photometry of the eccentric (e ~ 0.93) hot Jupiter HD80606b obtained with the Spitzer Space
Telescope. The planet’s extreme eccentricity combined with the long coverage and exquisite precision of new
periastron-passage observations allow us to break the degeneracy between the radiative and dynamical timescales
of HD80606b’s atmosphere and constrain its global thermal response. Our analysis reveals that the atmospheric
layers probed heat rapidly (∼4 hr radiative timescale) from<500 to 1400 K as they absorb ~20% of the incoming
stellar flux during the periastron passage, while the planet’s rotation period is 93 35
85
-
+ hr, which exceeds the predicted
pseudo-synchronous period (40 hr).
Key words: methods: numerical – planet–star interactions – planets and satellites: atmospheres – planets and
satellites: dynamical evolution and stability – planets and satellites: individual (HD 80606 b) – techniques:
photometric
Transit observations of_the_hot_jupiter_hd189733b_at_xray_wavelenghts
This document summarizes observations of the exoplanet HD 189733b taken with Chandra and XMM-Newton telescopes. The observations detected X-ray emissions from both the planet-hosting star HD 189733A and its companion star HD 189733B. A transit of HD 189733b in front of its star was detected in soft X-rays, with a transit depth of 6-8% compared to 2.41% in the optical. This is interpreted as evidence for an extended atmosphere around the planet that is opaque to X-rays but transparent at optical wavelengths. The magnetic activity of the companion star HD 189733B was also found to be inconsistent with the activity of the planet-hosting star, possibly due to
The mass of_the_mars_sized_exoplanet_kepler_138_b_from_transit_timing
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.
A seven-planet resonant chain in TRAPPIST-1
The TRAPPIST-1 system is the first transiting planet system
found orbiting an ultracool dwarf star1. At least seven planets
similar in radius to Earth were previously found to transit
this host star2. Subsequently, TRAPPIST-1 was observed as
part of the K2 mission and, with these new data, we report
the measurement of an 18.77 day orbital period for the outermost
transiting planet, TRAPPIST-1 h, which was previously
unconstrained. This value matches our theoretical expectations
based on Laplace relations3 and places TRAPPIST-1 h
as the seventh member of a complex chain, with three-body
resonances linking every member. We find that TRAPPIST-1 h
has a radius of 0.752 R⊕ and an equilibrium temperature of
173 K. We have also measured the rotational period of the star
to be 3.3 days and detected a number of flares consistent with
a low-activity, middle-aged, late M dwarf.
A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a
substantial fraction of other stars [1]. Population statistics show that
close-in planets in this size range bifurcate into two classes based
on their radii [2, 3]. It is hypothesized that the group with larger
radii (referred to as “sub-Neptunes”) is distinguished by having
hydrogen-dominated atmospheres that are a few percent of the total
mass of the planets [4]. GJ 1214b is an archetype sub-Neptune that
has been observed extensively using transmission spectroscopy to
test this hypothesis [5–14]. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude
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Springer Nature 2021 LATEX template
GJ 1214b Phase Curve 3
aerosols in the planet’s atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with JWST in the
mid-infrared. The dayside and nightside spectra (average brightness
temperatures of 553 ± 9 and 437 ± 19 K, respectively) each show > 3σ
evidence of absorption features, with H2O as the most likely cause in
both. The measured global thermal emission implies that GJ 1214b’s
Bond albedo is 0.51 ± 0.06. Comparison between the spectroscopic
phase curve data and three-dimensional models of GJ 1214b reveal
a planet with a high metallicity atmosphere blanketed by a thick
and highly reflective layer of clouds or haze.
A precise water_abundance_measurement_for_the_hot_jupiter_wasp_43b
This document presents a precise measurement of the water abundance in the atmosphere of the exoplanet WASP-43b using transmission and thermal emission spectroscopy from the Hubble Space Telescope. The key findings are:
1) The water content of WASP-43b's atmosphere is consistent with solar composition at planetary temperatures, ranging from 0.4 to 3.5 times the solar water abundance.
2) This metallicity measurement extends the trend seen in the solar system of lower metal enrichment for higher mass planets.
3) Measuring a planet's water content constrains its formation location in the protoplanetary disk and provides insight into planetary formation models.
An Earth-sized exoplanet with a Mercury-like composition
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.
Detection of solar_like_oscillations_in_relies_of_the_milk_way_asteroseismolo...
Asteroseismic constraints on K giants make it possible to infer radii, masses and ages of tens
of thousands of field stars. Tests against independent estimates of these properties are however
scarce, especially in the metal-poor regime. Here, we report the detection of solar-like
oscillations in 8 stars belonging to the red-giant branch and red-horizontal branch of the globular
cluster M4. The detections were made in photometric observations from the K2 Mission
during its Campaign 2. Making use of independent constraints on the distance, we estimate
masses of the 8 stars by utilising different combinations of seismic and non-seismic inputs.
When introducing a correction to the Δν scaling relation as suggested by stellar models, for
RGB stars we find excellent agreement with the expected masses from isochrone fitting, and
with a distance modulus derived using independent methods. The offset with respect to independent
masses is lower, or comparable with, the uncertainties on the average RGB mass
(4 − 10%, depending on the combination of constraints used). Our results lend confidence to
asteroseismic masses in the metal poor regime. We note that a larger sample will be needed
to allow more stringent tests to be made of systematic uncertainties in all the observables
(both seismic and non-seismic), and to explore the properties of RHB stars, and of different
populations in the cluster.
The Pulsar Mass Distribution
1) The document summarizes recent measurements of pulsar masses, finding 35 precision measurements including some with masses over 1.8 solar masses.
2) It discusses possible formation scenarios for eccentric millisecond pulsars that could provide constraints on neutron star structure if their masses are measured precisely.
3) The mass distribution of millisecond pulsars is likely bimodal rather than normal, with peaks at 1.4 and 1.8 solar masses, implying more massive pulsars are common than previously thought.
Kepler 62 a_five_planet_system_with_planets_of_1_4_and_1_6_earth_radii_in_the...
This document reports the detection of five planets orbiting the star Kepler-62, including two super-Earth-size planets (Kepler-62e and Kepler-62f) in the habitable zone of the star. Kepler-62e receives 1.2 times the solar flux at Earth's orbit, while Kepler-62f receives 0.41 times the solar flux. Theoretical models suggest that both planets could be solid, with either a rocky composition or composed mostly of solid water.
Science with small telescopes - exoplanets
The search for extrasolar planets has become one of the most attractive problems in modern astrophysics. The biggest observatories in the world are involved in this task as well as little amateur instruments. There is also a huge variety of astronomical methods used for their investigation. Here I present the projects for searching for exoplanets by transit method and our observations of the planet WASP-2b. We observed a transit on 3/4 August 2008 with a 354 mm Schmidt-Cassegrain Celestron telescope and CCD SBIG STL 11000M camera. By precise photometry made using MaximDL software we obtained the light curve of the star system. Decrease of brightness by 0.02m is detected. Analyzing our data we estimate the radius of the planet and inclination of its orbit. Our results are in good correlation with the published information in literature.
Nature12917
1) PSR J033711715 is a millisecond pulsar discovered to be in a hierarchical triple system with two white dwarf companions, making it the first known millisecond pulsar triple system.
2) Precise timing observations using multiple radio telescopes determined the masses of the pulsar (1.4378 solar masses), inner white dwarf companion (0.19751 solar masses), and outer white dwarf companion (0.4101 solar masses) to high precision.
3) The unexpectedly coplanar and nearly circular orbits of the system indicate an exotic evolutionary history and provide an opportunity to test theories of general relativity by studying the interactions between the bodies.
Measurement of Jupiter’s asymmetric gravity field
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.
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...
This document summarizes the results of a study analyzing the total mass density profiles of 14 early-type galaxies using two-dimensional stellar kinematic data out to large radii of 2-6 half-light radii. The study finds that the total density profiles are well described by a nearly-isothermal power law with density proportional to radius from 0.1 to at least 4 half-light radii. The average logarithmic slope is -2.19 with a small scatter of only 0.11. This places tight constraints on galaxy formation models and illustrates the power of extended two-dimensional stellar kinematic observations.
Discovery of rotational modulations in the planetary mass companion 2m1207b i...
Rotational modulations of brown dwarfs have recently provided powerful constraints on the properties
of ultra-cool atmospheres, including longitudinal and vertical cloud structures and cloud evolution.
Furthermore, periodic light curves directly probe the rotational periods of ultra-cool objects. We
present here, for the first time, time-resolved high-precision photometric measurements of a planetarymass
companion, 2M1207b. We observed the binary system with HST/WFC3 in two bands and with
two spacecraft roll angles. Using point spread function-based photometry, we reach a nearly photonnoise
limited accuracy for both the primary and the secondary. While the primary is consistent with
a flat light curve, the secondary shows modulations that are clearly detected in the combined light
curve as well as in di↵erent subsets of the data. The amplitudes are 1.36% in the F125W and 0.78%
in the F160W filters, respectively. By fitting sine waves to the light curves, we find a consistent period
of 10.7+1.2
−0.6 hours and similar phases in both bands. The J- and H-band amplitude ratio of 2M1207b
is very similar to a field brown dwarf that has identical spectral type but di↵erent J-H color. Importantly,
our study also measures, for the first time, the rotation period for a directly imaged extra-solar
planetary-mass companion.
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2
This document reports the discovery of three transiting super-Earth planets orbiting a nearby bright M0 dwarf star, EPIC 201367065, using data from the K2 mission. Photometry from K2 reveals three planetary candidates with orbital periods of 10.056, 24.641, and ~45 days and radii between 1.5-2.1 Earth radii. Spectroscopy of the host star determines it has a mass of 0.601 solar masses, radius of 0.561 solar radii, and is located about 45 parsecs away, making the planets some of the coolest small planets known around a nearby star. The system presents an opportunity to measure the planet masses and constrain atmospheric compositions via future observations
Nature12888
1) Researchers observed 15 transits of the exoplanet GJ 1214b using the Hubble Space Telescope to measure its transmission spectrum from 1.1 to 1.7 microns.
2) The transmission spectrum was featureless, inconsistent with cloud-free atmospheres dominated by water, methane, carbon monoxide, nitrogen, or carbon dioxide.
3) The most likely explanation for the featureless spectrum is the presence of high-altitude clouds in the planet's atmosphere, which block the transmission of stellar light through the lower atmosphere.
The atacama cosmology_telescope_measuring_radio_galaxy_bias_through_cross_cor...
A radiação cósmica de micro-ondas aponta para a matéria escura invisível, marcando o ponto onde jatos de material viajam a velocidades próximas da velocidade da luz, de acordo com uma equipe internacional de astrônomos. O principal autor do estudo, Rupert Allison da Universidade de Oxford apresentou os resultados no dia 6 de Julho de 2015 no National Astronomy Meeting em Venue Cymru, em Llandudno em Wales.
Atualmente, ninguém sabe ao certo do que a matéria escura é feita, mas ela é responsável por cerca de 26% do conteúdo de energia do universo, com galáxias massivas se formando em densas regiões de matéria escura. Embora invisível, a matéria escura se mostra através do efeito gravitacional – uma grande bolha de matéria escura puxa a matéria normal (como elétrons, prótons e nêutrons) através de sua própria gravidade, eventualmente se empacotando conjuntamente para criar as estrelas e galáxias inteiras.
Muitas das maiores dessas são galáxias ativas com buracos negros supermassivos em seus centros. Alguma parte do gás caindo diretamente na direção do buraco negro é ejetada como jatos de partículas e radiação. As observações feitas com rádio telescópios mostram que esses jatos as vezes se espalham por milhões de anos-luz desde a galáxia – mais distante até mesmo do que a extensão da própria galáxia.
Os cientistas esperam que os jatos possam viver em regiões onde existe um excesso de concentração da matéria escura, maior do que o da média. Mas como a matéria escura é invisível, testar essa ideia não é algo tão direto.
Detection of an atmosphere around the super earth 55 cancri e
We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near
infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent
star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness
of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length
and a very high scanning speed. We use our specialized pipeline to take into account systematics
introduced by these observational parameters when coupled with the geometrical distortions of the
instrument. We measure the transit depth per wavelength channel with an average relative uncertainty
of 22 ppm per visit and nd modulations that depart from a straight line model with a 6 con dence
level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably
hydrogen-rich. Our fully Bayesian spectral retrieval code, T -REx, has identi ed HCN to be the
most likely molecular candidate able to explain the features at 1.42 and 1.54 m. While additional
spectroscopic observations in a broader wavelength range in the infrared will be needed to con rm
the HCN detection, we discuss here the implications of such result. Our chemical model, developed
with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a
high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic
than previously thought.
Similar to Spencer_AAS (20)
Direct Measure of Radiative And Dynamical Properties Of An Exoplanet Atmosphere
Direct Measure of Radiative And Dynamical Properties Of An Exoplanet Atmosphere
Transit observations of_the_hot_jupiter_hd189733b_at_xray_wavelenghts
Transit observations of_the_hot_jupiter_hd189733b_at_xray_wavelenghts
The mass of_the_mars_sized_exoplanet_kepler_138_b_from_transit_timing
The mass of_the_mars_sized_exoplanet_kepler_138_b_from_transit_timing
A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
A precise water_abundance_measurement_for_the_hot_jupiter_wasp_43b
A precise water_abundance_measurement_for_the_hot_jupiter_wasp_43b
An Earth-sized exoplanet with a Mercury-like composition
An Earth-sized exoplanet with a Mercury-like composition
Detection of solar_like_oscillations_in_relies_of_the_milk_way_asteroseismolo...
Detection of solar_like_oscillations_in_relies_of_the_milk_way_asteroseismolo...
Kepler 62 a_five_planet_system_with_planets_of_1_4_and_1_6_earth_radii_in_the...
Kepler 62 a_five_planet_system_with_planets_of_1_4_and_1_6_earth_radii_in_the...
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...
Discovery of rotational modulations in the planetary mass companion 2m1207b i...
Discovery of rotational modulations in the planetary mass companion 2m1207b i...
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2
A nearby m_star_with_three_transiting_super-earths_discovered_by_k2
The atacama cosmology_telescope_measuring_radio_galaxy_bias_through_cross_cor...
The atacama cosmology_telescope_measuring_radio_galaxy_bias_through_cross_cor...
Detection of an atmosphere around the super earth 55 cancri e
Detection of an atmosphere around the super earth 55 cancri e
Spencer_AAS
- 1. Atmospheric evaporation in super-Earth exoplanet systems Spencer R. Moller1, Brendan Miller1, Elena Gallo2, Jason Wright3, Katja Poppenhaeger4 1College of St. Scholastica 2University of Michigan 3Pennsylvania State University 4Queens University Belfast Can Stellar Activity Transform Planets? • We wish to investigate how high-energy stellar radiation can heat, inflate, and evaporate planetary atmospheres of close-in exoplanets (Lammer+03; see also Jackson+16) • X-ray observations measure the flux incident at the planet, and can be used to estimate the mass loss rate (Poppenhaeger+12) • Test whether inner planets may be transformed into higher- density cores (Lammer+09; Jackson+10; Lopez+12; Salz+15) • We consider nearby planets with both transit and radial-velocity measurements (hence known densities) constructed from the Exoplanet Orbit Database (Wright+12; Han+14; Figure 1) We investigate the influence of stellar activity on atmospheric heating and evaporation in four super-Earth exoplanets: HD 97658 b, GJ 1214 b, 55 Cnc e, and CoRoT-7 b. We use X-ray observations of the host stars to estimate planetary mass loss. We extracted net count rates from a soft band image, converted it to flux using PIMMS for a standard coronal model, calculated the intrinsic stellar luminosity, and estimated the current-epoch mass-loss rate and the integrated mass lost. Our aim is to determine under what circumstances current super-Earths will have experienced significant mass loss through atmospheric irradiation over the system lifetime. We hypothesize that closely-orbiting exoplanets receiving the greatest amount of high-energy stellar radiation will also tend to be sculpted into lower mass and more dense remnant cores. X-ray data observations • Use Chandra ACIS-S3 for low background and relatively high soft X-ray sensitivity; all targets were detected (Figure 2) • The net counts within a 2’’ extraction radius are used to determine net rates per ks of 1.51 for 55 Cnc e and 1.22 for HD 97658, which are then converted into flux (at Earth) for a standard coronal model using PIMMS • We also use archival Chandra or XMM-Newton data, including for CoRoT-7 (Poppenhaeger+10, 12; Lalitha+14) • At distances of 12.34, 150, 12.95 and 21.11 pc, these indicate 0.2- 3 keV X-ray luminosities of log Lx = 26.1, 28.5, 25.8, and 26.5, for 55 Cnc e, CoRoT-7 b, GJ 1214 and HD 97658, respectively Stellar irradiation and estimated mass loss • The 0.2-3 keV X-ray fluxes at the planetary orbital radii are, in log values, 2.27, 4.58, 2.04 and 1.25 erg s-1 cm-2 for 55 Cnc e, CoRoT-7 b, GJ 1214 and HD 97658 • We estimate the EUV luminosity using the relationship from Sanz-Forcata+11 (but see Salz+15); our upcoming Swift UV observations will help refine values • The XUV flux is then used to estimate the current mass loss rate (Figure 3) following Poppenhaeger+12 and Lalitha+14 (see also Erkaev+07; Jackson+10) Erkaev, N. V., et al. 2007, A&A, 472, 329 Han, E., Wang, S. X., Wright, J. T., et al. 2014, PASP, 126, 827 Jackson, B., et al. 2010, MNRAS, 407, 910 Jackson, B., et al. 2016, ApJ, 2016, arXiv:1612.04332 Lalitha, S., et al. 2014, ApJ, 790, L11 Lammer, H., et al. 2003, ApJ, 598, L121 Lammer, H., et al. 2009, A&A, 506, 399 We gratefully acknowledge support for this work from Chandra Award GO5-16012X Figure 1: Nearby (<150 pc) transiting exoplanets with radial-velocity established masses; only a handful are super Earths Figure 2: Chandra X-ray images of 55 Cnc e (left) and HD 97658 (right). Figure 3: Estimated mass loss rates versus Lx values for Super-Earth systems Figure 4: Integrated mass loss for CoRoT-7 b, GJ 1214 b,55 Cnc e, and HD 97658 b. Lopez, E. D., Fortney, J. J., & Miller, N. 2012, ApJ, 761, 59 Poppenhaeger, K., et al. 2010, A&A, 515, A98 Poppenhaeger, K., et al. 2012, A&A, 541, A26 Ribas, I., et al. 2005, ApJ, 622, 680 Salz, M., et al. 2015, A&A, 576, 42 Sanz-Forcada, J., et al. 2011, A&A, 532, A6 Wright, J. T., et al. 2012, ApJ, 753, 160 Key: ● Fxuv = incident XUV flux at the planetary orbit ● G = gravitational constant ● Pp= planetary density ● ε = heating efficiency (0.4) ● K= Roche Lobe overflow (1) NAME Dists(pc) rates lx Orbit(au) fx fxuv Rho (g/cm^3) mdot0 Stellar ages(Gyr) HD 97658 b 21.11 0.00122 26.461 0.0796 1.210 2.182e+02 3.44 2.851e+08 6 GJ 1214 b 12.95 XMM 25.820 0.01433 2.058 1.867e+03 1.87 4.488e+9 6 55 Cnc e 12.34 0.00151 26.087 0.01544 2.261 2.7434e+03 4.17 2.957e+09 8 CoRoT-7 b 150 XMM 28.480 0.01719 4.570 1.661e+05 6.20 1.204e+11 1.5