{"topic":"exoplanets-biosignatures","sort":"top","limit":25,"offset":0,"count":25,"papers":[{"id":"arxiv:2211.10487","kind":"article","title":"Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM","authors":["Zafar Rustamkulov","David K. Sing","S. Mukherjee","Erin May","James A. Kirk","Everett A. Schlawin","Michael Line","Caroline Piaulet","Aarynn L. Carter","Natasha E. Batalha","Jayesh Goyal","Mercedes López‐Morales","Joshua D. Lothringer","R. J. MacDonald","Sarah E. Moran","Kevin B. Stevenson","Hannah R. Wakeford","N. Espinoza","Jacob L. Bean","Natalie M. Batalha","Bjoern Benneke","Zachory K. Berta-Thompson","Ian J. M. Crossfield","Peter Gao","Laura Kreidberg"],"author_count":94,"year":2023,"published":"2023-01-09","venue":"Nature","cited_by":328,"doi":"10.1038/s41586-022-05677-y","arxiv_id":"2211.10487","nct_id":null,"source_url":"https://doi.org/10.1038/s41586-022-05677-y","archive_url":"https://space-kitty.com/papers/arxiv:2211.10487","updated":"2022-11-18","pmid":"36623548","pmcid":null,"openalex_id":"W4315436844","pdf_url":"https://www.nature.com/articles/s41586-022-05677-y.pdf","abstract":"Transmission spectroscopy of exoplanets has revealed signatures of water vapor, aerosols, and alkali metals in a few dozen exoplanet atmospheres. However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations' relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species$-$in particular the primary carbon-bearing molecules. Here we report a broad-wavelength 0.5-5.5 $μ$m atmospheric transmission spectrum of WASP-39 b, a 1200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with JWST NIRSpec's PRISM mode as part of the JWST Transiting Exoplanet Community Early Release Science Team program. We robustly detect multiple chemical species at high significance, including Na (19$σ$), H$_2$O (33$σ$), CO$_2$ (28$σ$), and CO (7$σ$). The non-detection of CH$_4$, combined with a strong CO$_2$ feature, favours atmospheric models with a super-solar atmospheric metallicity. An unanticipated absorption feature at 4$μ$m is best explained by SO$_2$ (2.7$σ$), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST's sensitivity to a rich diversity of exoplanet compositions and chemical processes.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1711.05691","kind":"article","title":"The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets","authors":["Benjamin V. Rackham","Dániel Apai","Mark S. Giampapa"],"author_count":3,"year":2018,"published":"2018-01-30","venue":"The Astrophysical Journal","cited_by":421,"doi":"10.3847/1538-4357/aaa08c","arxiv_id":"1711.05691","nct_id":null,"source_url":"https://doi.org/10.3847/1538-4357/aaa08c","archive_url":"https://space-kitty.com/papers/arxiv:1711.05691","updated":"2018-01-24","pmid":null,"pmcid":null,"openalex_id":"W2769898786","pdf_url":"https://iopscience.iop.org/article/10.3847/1538-4357/aaa08c/pdf","abstract":"Transmission spectra are differential measurements that utilize stellar illumination to probe transiting exoplanet atmospheres. Any spectral difference between the illuminating light source and the disk-integrated stellar spectrum due to starspots and faculae will be imprinted in the observed transmission spectrum. However, few constraints exist for the extent of photospheric heterogeneities in M dwarfs. Here, we model spot and faculae covering fractions consistent with observed photometric variabilities for M dwarfs and the associated 0.3-5.5 $μ$m stellar contamination spectra. We find that large ranges of spot and faculae covering fractions are consistent with observations and corrections assuming a linear relation between variability amplitude and covering fractions generally underestimate the stellar contamination. Using realistic estimates for spot and faculae covering fractions, we find stellar contamination can be more than $10 \\times$ larger than transit depth changes expected for atmospheric features in rocky exoplanets. We also find that stellar spectral contamination can lead to systematic errors in radius and therefore the derived density of small planets. In the case of the TRAPPIST-1 system, we show that TRAPPIST-1's rotational variability is consistent with spot covering fractions $f_{spot} = 8^{+18}_{-7}\\%$ and faculae covering fractions $f_{fac} = 54^{+16}_{-46}\\%$. The associated stellar contamination signals alter transit depths of the TRAPPIST-1 planets at wavelengths of interest for planetary atmospheric species by roughly 1-15 $\\times$ the strength of planetary features, significantly complicating $JWST$ follow-up observations of this system. Similarly, we find stellar contamination can lead to underestimates of bulk densities of the TRAPPIST-1 planets of $Δ(ρ) = -3^{+3}_{-8} \\%$, thus leading to overestimates of their volatile contents.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:2309.05566","kind":"article","title":"Carbon-bearing Molecules in a Possible Hycean Atmosphere","authors":["Nikku Madhusudhan","Subhajit Sarkar","Savvas Constantinou","Måns Holmberg","Anjali A. A. Piette","Julianne I. Moses"],"author_count":6,"year":2023,"published":"2023-10-01","venue":"The Astrophysical Journal Letters","cited_by":279,"doi":"10.3847/2041-8213/acf577","arxiv_id":"2309.05566","nct_id":null,"source_url":"https://doi.org/10.3847/2041-8213/acf577","archive_url":"https://space-kitty.com/papers/arxiv:2309.05566","updated":"2023-10-04","pmid":null,"pmcid":null,"openalex_id":"W4387460386","pdf_url":"https://iopscience.iop.org/article/10.3847/2041-8213/acf577/pdf","abstract":"The search for habitable environments and biomarkers in exoplanetary atmospheres is the holy grail of exoplanet science. The detection of atmospheric signatures of habitable Earth-like exoplanets is challenging due to their small planet-star size contrast and thin atmospheres with high mean molecular weight. Recently, a new class of habitable exoplanets, called Hycean worlds, has been proposed, defined as temperate ocean-covered worlds with H2-rich atmospheres. Their large sizes and extended atmospheres, compared to rocky planets of the same mass, make Hycean worlds significantly more accessible to atmospheric spectroscopy with the JWST. Here we report a transmission spectrum of the candidate Hycean world, K2-18 b, observed with the JWST NIRISS and NIRSpec instruments in the 0.9-5.2 $μ$m range. The spectrum reveals strong detections of methane (CH4) and carbon dioxide (CO2) at 5$σ$ and 3$σ$ confidence, respectively, with high volume mixing ratios of ~1% each in a H2-rich atmosphere. The abundant CH4 and CO2 along with the non-detection of ammonia (NH3) are consistent with chemical predictions for an ocean under a temperate H2-rich atmosphere on K2-18 b. The spectrum also suggests potential signs of dimethyl sulfide (DMS), which has been predicted to be an observable biomarker in Hycean worlds, motivating considerations of possible biological activity on the planet. The detection of CH4 resolves the long-standing missing methane problem for temperate exoplanets and the degeneracy in the atmospheric composition of K2-18 b from previous observations. We discuss possible implications of the findings, open questions, and future observations to explore this new regime in the search for life elsewhere.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1511.05528","kind":"article","title":"CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST","authors":["Thomas P. Greene","Michael R. Line","Cezar Montero","Jonathan J. Fortney","Jacob Lustig-Yaeger","Kyle Luther"],"author_count":6,"year":2016,"published":"2016-01-19","venue":"The Astrophysical Journal","cited_by":385,"doi":"10.3847/0004-637x/817/1/17","arxiv_id":"1511.05528","nct_id":null,"source_url":"https://doi.org/10.3847/0004-637x/817/1/17","archive_url":"https://space-kitty.com/papers/arxiv:1511.05528","updated":"2015-11-17","pmid":null,"pmcid":null,"openalex_id":"W2249740070","pdf_url":"https://iopscience.iop.org/article/10.3847/0004-637X/817/1/17/pdf","abstract":"We explore how well James Webb Space Telescope (JWST) spectra will likely constrain bulk atmospheric properties of transiting exoplanets. We start by modeling the atmospheres of archetypal hot Jupiter, warm Neptune, warm sub-Neptune, and cool super-Earth planets with clear, cloudy, or high mean molecular weight atmospheres. Next we simulate the $λ= 1 - 11$ $μ$m transmission and emission spectra of these systems for several JWST instrument modes for single transit and eclipse events. We then perform retrievals to determine how well temperatures and molecular mixing ratios (CH$_4$, CO, CO$_2$, H$_2$O, NH$_3$) can be constrained. We find that $λ= 1 - 2.5$ $μ$m transmission spectra will often constrain the major molecular constituents of clear solar composition atmospheres well. Cloudy or high mean molecular weight atmospheres will often require full $1 - 11$ $μ$m spectra for good constraints, and emission data may be more useful in cases of sufficiently high $F_p$ and high $F_p/F_*$. Strong temperature inversions in the solar composition hot Jupiter atmosphere should be detectable with $1 - 2.5+$ $μ$m emission spectra, and $1 - 5+$ $μ$m emission spectra will constrain the temperature-pressure profiles of warm planets. Transmission spectra over $1 - 5+$ $μ$m will constrain [Fe/H] values to better than 0.5 dex for the clear atmospheres of the hot and warm planets studied. Carbon-to-oxygen ratios can be constrained to better than a factor of 2 in some systems. We expect that these results will provide useful predictions of the scientific value of single event JWST spectra until its on-orbit performance is known.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"doi:10.1038/s41586-022-05591-3","kind":"article","title":"Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H","authors":["Lili Alderson","Hannah R. Wakeford","Munazza K. Alam","Natasha E. Batalha","Joshua D. Lothringer","Jéa Adams Redai","Saugata Barat","Jonathan Brande","Mario Damiano","Tansu Daylan","Néstor Espinoza","Laura Flagg","Jayesh Goyal","David Grant","Renyu Hu","Julie Inglis","Elspeth K. H. Lee","T. M. Evans","Lakeisha M. Ramos Rosado","Pierre-Alexis Roy","Nicole L. Wallack","Natalie M. Batalha","Jacob L. Bean","Björn Benneke","Zachory K. Berta-Thompson"],"author_count":92,"year":2023,"published":"2023-01-09","venue":"Nature","cited_by":276,"doi":"10.1038/s41586-022-05591-3","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1038/s41586-022-05591-3","archive_url":"https://space-kitty.com/papers/doi:10.1038/s41586-022-05591-3","updated":null,"pmid":"36623549","pmcid":null,"openalex_id":"W4313893525","pdf_url":"https://www.nature.com/articles/s41586-022-05591-3.pdf","abstract":"Abstract Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems 1,2 . Access to the chemical inventory of an exoplanet requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based 3–5 and high-resolution ground-based 6–8 facilities. Here we report the medium-resolution ( R ≈ 600) transmission spectrum of an exoplanet atmosphere between 3 and 5 μm covering several absorption features for the Saturn-mass exoplanet WASP-39b (ref. 9 ), obtained with the Near Infrared Spectrograph (NIRSpec) G395H grating of JWST. Our observations achieve 1.46 times photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO 2 (28.5 σ ) and H 2 O (21.5 σ ), and identify SO 2 as the source of absorption at 4.1 μm (4.8 σ ). Best-fit atmospheric models range between 3 and 10 times solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO 2 , underscore the importance of characterizing the chemistry in exoplanet atmospheres and showcase NIRSpec G395H as an excellent mode for time-series observations over this critical wavelength range 10 .","abstract_license":"CC-BY (publisher license, via OpenAlex)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex","attribution":"Abstract of \"Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H\" by Lili Alderson, Hannah R. Wakeford, Munazza K. Alam et al., https://doi.org/10.1038/s41586-022-05591-3, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified."},{"id":"doi:10.1038/s41586-023-05902-2","kind":"article","title":"Photochemically produced SO2 in the atmosphere of WASP-39b","authors":["Shang‐Min Tsai","Elspeth K. H. Lee","Diana Powell","Peter Gao","Xi Zhang","Julianne I. Moses","Éric Hébrard","Olivia Vénot","Vivien Parmentier","Sean Jordan","Renyu Hu","Munazza K. Alam","Lili Alderson","Natalie M. Batalha","Jacob L. Bean","Björn Benneke","C. J. Bierson","Ryan P. Brady","L. Carone","Aarynn L. Carter","Katy L. Chubb","Julie Inglis","Jérémy Leconte","Michael Line","Mercedes López‐Morales"],"author_count":85,"year":2023,"published":"2023-04-26","venue":"Nature","cited_by":266,"doi":"10.1038/s41586-023-05902-2","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1038/s41586-023-05902-2","archive_url":"https://space-kitty.com/papers/doi:10.1038/s41586-023-05902-2","updated":null,"pmid":"37100917","pmcid":null,"openalex_id":"W4367049026","pdf_url":"https://www.nature.com/articles/s41586-023-05902-2.pdf","abstract":"Abstract Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability 1 . However, no unambiguous photochemical products have been detected in exoplanet atmospheres so far. Recent observations from the JWST Transiting Exoplanet Community Early Release Science Program 2,3 found a spectral absorption feature at 4.05 μm arising from sulfur dioxide (SO 2 ) in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 M J ) gas giant exoplanet orbiting a Sun-like star with an equilibrium temperature of around 1,100 K (ref. 4 ). The most plausible way of generating SO 2 in such an atmosphere is through photochemical processes 5,6 . Here we show that the SO 2 distribution computed by a suite of photochemical models robustly explains the 4.05-μm spectral feature identified by JWST transmission observations 7 with NIRSpec PRISM (2.7 σ ) 8 and G395H (4.5 σ ) 9 . SO 2 is produced by successive oxidation of sulfur radicals freed when hydrogen sulfide (H 2 S) is destroyed. The sensitivity of the SO 2 feature to the enrichment of the atmosphere by heavy elements (metallicity) suggests that it can be used as a tracer of atmospheric properties, with WASP-39b exhibiting an inferred metallicity of about 10× solar. We further point out that SO 2 also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations.","abstract_license":"CC-BY (publisher license, via OpenAlex)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex","attribution":"Abstract of \"Photochemically produced SO2 in the atmosphere of WASP-39b\" by Shang‐Min Tsai, Elspeth K. H. Lee, Diana Powell et al., https://doi.org/10.1038/s41586-023-05902-2, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified."},{"id":"arxiv:1803.02008","kind":"article","title":"Planetary Spectrum Generator: An accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets","authors":["G. L. Villanueva","Michael D. Smith","Silvia Protopapa","Sara Faggi","Avi M. Mandell"],"author_count":5,"year":2018,"published":"2018-05-29","venue":"Journal of Quantitative Spectroscopy and Radiative Transfer","cited_by":328,"doi":"10.1016/j.jqsrt.2018.05.023","arxiv_id":"1803.02008","nct_id":null,"source_url":"https://doi.org/10.1016/j.jqsrt.2018.05.023","archive_url":"https://space-kitty.com/papers/arxiv:1803.02008","updated":"2018-05-23","pmid":null,"pmcid":null,"openalex_id":"W2792721952","pdf_url":"https://arxiv.org/pdf/1803.02008","abstract":"We have developed an online radiative-transfer suite (https://psg.gsfc.nasa.gov) applicable to a broad range of planetary objects (e.g., planets, moons, comets, asteroids, TNOs, KBOs, exoplanets). The Planetary Spectrum Generator (PSG) can synthesize planetary spectra (atmospheres and surfaces) for a broad range of wavelengths (UV/Vis/near-IR/IR/far-IR/THz/sub-mm/Radio) from any observatory (e.g., JWST, ALMA, Keck, SOFIA), any orbiter (e.g., ExoMars, Juno), or any lander (e.g., MSL). This is achieved by combining several state-of-the-art radiative transfer models, spectroscopic databases and planetary databases (i.e., climatological and orbital). PSG has a 3D (three-dimensional) orbital calculator for most bodies in the solar system, and all confirmed exoplanets, while the radiative-transfer models can ingest billions of spectral signatures for hundreds of species from several spectroscopic repositories. It integrates the latest radiative-transfer and scattering methods in order to compute high resolution spectra via line-by-line calculations, and utilizes the efficient correlated-k method at moderate resolutions, while for computing cometary spectra, PSG handles non-LTE and LTE excitation processes. PSG includes a realistic noise calculator that integrates several telescope / instrument configurations (e.g., interferometry, coronagraphs) and detector technologies (e.g., CCD, heterodyne detectors, bolometers). Such an integration of advanced spectroscopic methods into an online tool can greatly serve the planetary community, ultimately enabling the retrieval of planetary parameters from remote sensing data, efficient mission planning strategies, interpretation of current and future planetary data, calibration of spectroscopic data, and development of new instrument/spacecraft concepts.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Astro and Planetary Science"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:2303.14849","kind":"article","title":"Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST","authors":["Thomas P. Greene","Taylor James Bell","Elsa Ducrot","Achrène Dyrek","Pierre-Olivier Lagage","Jonathan J. Fortney"],"author_count":6,"year":2023,"published":"2023-03-27","venue":"Nature","cited_by":244,"doi":"10.1038/s41586-023-05951-7","arxiv_id":"2303.14849","nct_id":null,"source_url":"https://doi.org/10.1038/s41586-023-05951-7","archive_url":"https://space-kitty.com/papers/arxiv:2303.14849","updated":"2023-05-31","pmid":"36972683","pmcid":null,"openalex_id":"W4360999796","pdf_url":"https://arxiv.org/pdf/2303.14849","abstract":"The TRAPPIST-1 system is remarkable for its seven planets that are similar in size, mass, density, and stellar heating to the rocky planets Venus, Earth, and Mars in our own Solar System (Gillon et al. 2017). All TRAPPIST-1 planets have been observed with the transmission spectroscopy technique using the Hubble or Spitzer Space Telescopes, but no atmospheric features have been detected or strongly constrained (Ducrot et al. 2018; de Wit et al. 2018; Zhang et al. 2018; Garcia et al. 2022). TRAPPIST-1 b is the closest planet to the system's M dwarf star, and it receives 4 times as much irradiation as Earth receives from the Sun. This relatively large amount of stellar heating suggests that its thermal emission may be measurable. Here we present photometric secondary eclipse observations of the Earth-sized TRAPPIST-1 b exoplanet using the F1500W filter of the MIRI instrument on JWST. We detect the secondary eclipse in each of five separate observations with 8.7-$σ$ confidence when all data are combined. These measurements are most consistent with the re-radiation of the TRAPPIST-1 star's incident flux from only the dayside hemisphere of the planet. The most straightforward interpretation is that there is little or no planetary atmosphere redistributing radiation from the host star and also no detectable atmospheric absorption from carbon dioxide (CO$_2$) or other species.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"openalex:W3101474964","kind":"article","title":"CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST","authors":["Thomas P. Greene","Michael R. Line","Cezar Montero","Jonathan J. Fortney","Jacob Lustig‐Yaeger","Kyle Luther"],"author_count":6,"year":2016,"published":"2016-01-20","venue":"eScholarship (California Digital Library)","cited_by":308,"doi":null,"arxiv_id":null,"nct_id":null,"source_url":"https://escholarship.org/uc/item/51p598hp","archive_url":"https://space-kitty.com/papers/openalex:W3101474964","updated":null,"pmid":null,"pmcid":null,"openalex_id":"W3101474964","pdf_url":null,"abstract":null,"abstract_license":null,"license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex","attribution":"Metadata and citation counts: OpenAlex (CC0)."},{"id":"arxiv:1005.4037","kind":"article","title":"Exoplanet Atmospheres","authors":["S. Seager","D. Deming"],"author_count":2,"year":2010,"published":"2010-05-21","venue":"Annual Review of Astronomy and Astrophysics","cited_by":435,"doi":"10.1146/annurev-astro-081309-130837","arxiv_id":"1005.4037","nct_id":null,"source_url":"https://arxiv.org/abs/1005.4037","archive_url":"https://space-kitty.com/papers/arxiv:1005.4037","updated":"2010-05-21","pmid":null,"pmcid":null,"openalex_id":"W3037016578","pdf_url":"https://arxiv.org/pdf/1005.4037","abstract":"At the dawn of the first discovery of exoplanets orbiting sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features; observation of day-night temperature gradients; and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, \"Are we alone?\" via detection of atmospheric biosignatures. Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and ultimately the spaceborne direct imaging of true Earth analogs.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["astro-ph.EP"],"details":null,"provenance":"arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"doi:10.1086/679566","kind":"article","title":"Observations of Transiting Exoplanets with the James Webb Space Telescope (JWST)","authors":["Charles Beichman","Bjoern Benneke","Heather A. Knutson","Roger M. Smith","Pierre-Olivier Lagage","Courtney D. Dressing","David W. Latham","Jonathan I. Lunine","Stephan M. Birkmann","Pierre Ferruit","Giovanna Giardino","Eliza M.-R. Kempton","Sean J. Carey","Jessica Krick","Pieter D. Deroo","Avi M. Mandell","Michael E. Ressler","Avi Shporer","Mark G. Swain","Gautam Vasisht","George R. Ricker","Jeroen Bouwman","Ian J. M. Crossfield","Tom Greene","Steve B. Howell"],"author_count":48,"year":2014,"published":"2014-12-01","venue":"Publications of the Astronomical Society of the Pacific","cited_by":283,"doi":"10.1086/679566","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1086/679566","archive_url":"https://space-kitty.com/papers/doi:10.1086/679566","updated":null,"pmid":null,"pmcid":null,"openalex_id":"W2090778108","pdf_url":null,"abstract":null,"abstract_license":null,"license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex","attribution":"Metadata and citation counts: OpenAlex (CC0)."},{"id":"arxiv:2306.10150","kind":"article","title":"No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c","authors":["Sebastian Zieba","Laura Kreidberg","Elsa Ducrot","M. Gillon","Caroline V. Morley","Laura Schaefer","Patrick Tamburo","Daniel D. B. Koll","Xintong Lyu","L. Acuña","Eric Agol","Aishwarya R. Iyer","Renyu Hu","Andrew Lincowski","Victoria Meadows","Franck Selsis","Émeline Bolmont","Avi M. Mandell","Gabrielle Suissa"],"author_count":19,"year":2023,"published":"2023-06-19","venue":"Nature","cited_by":220,"doi":"10.1038/s41586-023-06232-z","arxiv_id":"2306.10150","nct_id":null,"source_url":"https://doi.org/10.1038/s41586-023-06232-z","archive_url":"https://space-kitty.com/papers/arxiv:2306.10150","updated":"2023-06-16","pmid":"37337068","pmcid":null,"openalex_id":"W4381249309","pdf_url":"https://www.nature.com/articles/s41586-023-06232-z.pdf","abstract":"Seven rocky planets orbit the nearby dwarf star TRAPPIST-1, providing a unique opportunity to search for atmospheres on small planets outside the Solar System (Gillon et al., 2017). Thanks to the recent launch of JWST, possible atmospheric constituents such as carbon dioxide (CO2) are now detectable (Morley et al., 2017, Lincowski et al., 2018}. Recent JWST observations of the innermost planet TRAPPIST-1 b showed that it is most probably a bare rock without any CO2 in its atmosphere (Greene et al., 2023). Here we report the detection of thermal emission from the dayside of TRAPPIST-1 c with the Mid-Infrared Instrument (MIRI) on JWST at 15 micron. We measure a planet-to-star flux ratio of fp/fs = 421 +/- 94 parts per million (ppm) which corresponds to an inferred dayside brightness temperature of 380 +/- 31 K. This high dayside temperature disfavours a thick, CO2-rich atmosphere on the planet. The data rule out cloud-free O2/CO2 mixtures with surface pressures ranging from 10 bar (with 10 ppm CO2) to 0.1 bar (pure CO2). A Venus-analogue atmosphere with sulfuric acid clouds is also disfavoured at 2.6 sigma confidence. Thinner atmospheres or bare-rock surfaces are consistent with our measured planet-to-star flux ratio. The absence of a thick, CO2-rich atmosphere on TRAPPIST-1 c suggests a relatively volatile-poor formation history, with less than 9.5 +7.5 -2.3 Earth oceans of water. If all planets in the system formed in the same way, this would indicate a limited reservoir of volatiles for the potentially habitable planets in the system.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:2504.12267","kind":"article","title":"New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI","authors":["Nikku Madhusudhan","Savvas Constantinou","Måns Holmberg","Subhajit Sarkar","Anjali A. A. Piette","Julianne I. Moses"],"author_count":6,"year":2025,"published":"2025-04-16","venue":"The Astrophysical Journal Letters","cited_by":82,"doi":"10.3847/2041-8213/adc1c8","arxiv_id":"2504.12267","nct_id":null,"source_url":"https://arxiv.org/abs/2504.12267","archive_url":"https://space-kitty.com/papers/arxiv:2504.12267","updated":"2025-04-16","pmid":null,"pmcid":null,"openalex_id":"W4409554365","pdf_url":"https://arxiv.org/pdf/2504.12267","abstract":"The sub-Neptune frontier has opened a new window into the rich diversity of planetary environments beyond the solar system. The possibility of hycean worlds, with planet-wide oceans and H$_2$-rich atmospheres, significantly expands and accelerates the search for habitable environments elsewhere. Recent JWST transmission spectroscopy of the candidate hycean world K2-18 b in the near-infrared led to the first detections of carbon-bearing molecules CH$_4$ and CO$_2$ in its atmosphere, with a composition consistent with predictions for hycean conditions. The observations also provided a tentative hint of dimethyl sulfide (DMS), a possible biosignature gas, but the inference was of low statistical significance. We report a mid-infrared transmission spectrum of K2-18 b obtained using the JWST MIRI LRS instrument in the ~6-12 $μ$m range. The spectrum shows distinct features and is inconsistent with a featureless spectrum at 3.4-$σ$ significance compared to our canonical model. We find that the spectrum cannot be explained by most molecules predicted for K2-18 b with the exception of DMS and dimethyl disulfide (DMDS), also a potential biosignature gas. We report new independent evidence for DMS and/or DMDS in the atmosphere at 3-$σ$ significance, with high abundance ($\\gtrsim$10 ppmv) of at least one of the two molecules. More observations are needed to increase the robustness of the findings and resolve the degeneracy between DMS and DMDS. The results also highlight the need for additional experimental and theoretical work to determine accurate cross sections of important biosignature gases and identify potential abiotic sources. We discuss the implications of the present findings for the possibility of biological activity on K2-18 b.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["astro-ph.EP"],"details":null,"provenance":"arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1905.07070","kind":"article","title":"The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST","authors":["Jacob Lustig‐Yaeger","Victoria S. Meadows","Andrew Lincowski"],"author_count":3,"year":2019,"published":"2019-06-21","venue":"The Astronomical Journal","cited_by":252,"doi":"10.3847/1538-3881/ab21e0","arxiv_id":"1905.07070","nct_id":null,"source_url":"https://doi.org/10.3847/1538-3881/ab21e0","archive_url":"https://space-kitty.com/papers/arxiv:1905.07070","updated":"2019-05-17","pmid":null,"pmcid":null,"openalex_id":"W2945659149","pdf_url":"https://iopscience.iop.org/article/10.3847/1538-3881/ab21e0/pdf","abstract":"The James Webb Space Telescope (JWST) will offer the first opportunity to characterize terrestrial exoplanets with sufficient precision to identify high mean molecular weight atmospheres, and TRAPPIST-1's seven known transiting Earth-sized planets are particularly favorable targets. To assist community preparations for JWST, we use simulations of plausible post-ocean-loss and habitable environments for the TRAPPIST-1 exoplanets, and test simulations of all bright object time series spectroscopy modes and all MIRI photometry filters to determine optimal observing strategies for atmospheric detection and characterization using both transmission and emission observations. We find that transmission spectroscopy with NIRSpec Prism is optimal for detecting terrestrial, CO2 containing atmospheres, potentially in fewer than 10 transits for all seven TRAPPIST-1 planets, if they lack high altitude aerosols. If the TRAPPIST-1 planets possess Venus-like H2SO4 aerosols, up to 12 times more transits may be required to detect atmospheres. We present optimal instruments and observing modes for the detection of individual molecular species in a given terrestrial atmosphere and an observational strategy for discriminating between evolutionary states. We find that water may be prohibitively difficult to detect in both Venus-like and habitable atmospheres due to its presence lower in the atmosphere where transmission spectra are less sensitive. Although the presence of biogenic O2 and O3 will be extremely challenging to detect, abiotically produced oxygen from past ocean loss may be detectable for all seven TRAPPIST-1 planets via O2-O2 collisionally-induced absorption at 1.06 and 1.27 microns, or via NIR O3 features for the outer three planets. Our results constitute a suite of hypotheses on the nature and detectability of highly-evolved terrestrial exoplanet atmospheres that may be tested with JWST.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"doi:10.1038/s41586-022-05590-4","kind":"article","title":"Early Release Science of the exoplanet WASP-39b with JWST NIRCam","authors":["Eva-Maria Ahrer","Kevin B. Stevenson","Megan Mansfield","Sarah E. Moran","Jonathan Brande","Giuseppe Morello","Catriona Anne Murray","Nikolay Nikolov","D. J. M. Petit dit de la Roche","Everett A. Schlawin","Peter J Wheatley","Sebastian Zieba","Natasha E. Batalha","Mario Damiano","Jayesh Goyal","M. Lendl","Joshua D. Lothringer","Sagnick Mukherjee","Kazumasa Ohno","Natalie M. Batalha","Matthew P. Battley","Jacob L. Bean","Thomas G. Beatty","Björn Benneke","Zachory K. Berta-Thompson"],"author_count":99,"year":2023,"published":"2023-01-09","venue":"Nature","cited_by":198,"doi":"10.1038/s41586-022-05590-4","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1038/s41586-022-05590-4","archive_url":"https://space-kitty.com/papers/doi:10.1038/s41586-022-05590-4","updated":null,"pmid":"36623551","pmcid":null,"openalex_id":"W4313897562","pdf_url":"https://www.nature.com/articles/s41586-022-05590-4.pdf","abstract":"Abstract Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining the dominant chemical processes at work and, if in equilibrium, revealing planet formation histories. Transmission spectroscopy (for example, refs.1,2) provides the necessary means by constraining the abundances of oxygen- and carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution and high precision, which, together, are not achievable with previous observatories. Now that JWST has commenced science operations, we are able to observe exoplanets at previously uncharted wavelengths and spectral resolutions. Here we report time-series observations of the transiting exoplanet WASP-39b using JWST’s Near InfraRed Camera (NIRCam). The long-wavelength spectroscopic and short-wavelength photometric light curves span 2.0–4.0 micrometres, exhibit minimal systematics and reveal well defined molecular absorption features in the planet’s spectrum. Specifically, we detect gaseous water in the atmosphere and place an upper limit on the abundance of methane. The otherwise prominent carbon dioxide feature at 2.8 micrometres is largely masked by water. The best-fit chemical equilibrium models favour an atmospheric metallicity of 1–100-times solar (that is, an enrichment of elements heavier than helium relative to the Sun) and a substellar C/O ratio. The inferred high metallicity and low C/O ratio may indicate significant accretion of solid materials during planet formation (for example, refs.3,4,) or disequilibrium processes in the upper atmosphere (for example, refs.5,6).","abstract_license":"CC-BY (publisher license, via OpenAlex)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex","attribution":"Abstract of \"Early Release Science of the exoplanet WASP-39b with JWST NIRCam\" by Eva-Maria Ahrer, Kevin B. Stevenson, Megan Mansfield et al., https://doi.org/10.1038/s41586-022-05590-4, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified."},{"id":"arxiv:2305.00868","kind":"article","title":"High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations","authors":["Sarah E. Moran","Kevin B. Stevenson","David K. Sing","Ryan J. MacDonald","James A. Kirk","Jacob Lustig‐Yaeger","Sarah Peacock","L. C. Mayorga","Katherine A. Bennett","Mercedes López‐Morales","Erin May","Zafar Rustamkulov","Jeff A. Valenti","Jéa Adams Redai","Munazza K. Alam","Natasha E. Batalha","Guangwei Fu","Junellie Gonzalez-Quiles","Alicia N. Highland","Ethan Kruse","Joshua D. Lothringer","Kevin Ortiz Ceballos","Kristin S. Sotzen","Hannah R. Wakeford"],"author_count":24,"year":2023,"published":"2023-05-05","venue":"The Astrophysical Journal Letters","cited_by":183,"doi":"10.3847/2041-8213/accb9c","arxiv_id":"2305.00868","nct_id":null,"source_url":"https://doi.org/10.3847/2041-8213/accb9c","archive_url":"https://space-kitty.com/papers/arxiv:2305.00868","updated":"2026-03-04","pmid":null,"pmcid":null,"openalex_id":"W4376983012","pdf_url":"https://iopscience.iop.org/article/10.3847/2041-8213/accb9c/pdf","abstract":"Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether their host stars' highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun to determine whether or not the most favorable rocky worlds orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8-5.2 micron JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3x Earth's insolation) super-Earth GJ 486b (1.3 R$_{\\oplus}$ and 3.0 M$_{\\oplus}$). The measured spectrum from our two transits of GJ 486b deviates from a flat line at 2.2 - 3.3 $σ$, based on three independent reductions. Through a combination of forward and retrieval models, we determine that GJ 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of H2O > 10% to 2$σ$) or the transmission spectrum is contaminated by water present in cool unocculted starspots. We also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. While both retrieval scenarios provide equal quality fits ($χ^2_ν$ = 1.0) to our NIRSpec/G395H observations, shorter wavelength observations can break this degeneracy and reveal if GJ 486b sustains a water-rich atmosphere.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:2209.00620","kind":"article","title":"The JWST Early-release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 μm Spectrum of the Planetary-mass Companion VHS 1256–1257 b","authors":["Brittany Miles","Beth A. Biller","Polychronis Patapis","Kadin Worthen","Emily L. Rickman","Kielan K. W. Hoch","Andrew J. I. Skemer","Marshall D. Perrin","Niall Whiteford","Christine Chen","Benjamin A. Sargent","Sagnick Mukherjee","Caroline V. Morley","Sarah E. Moran","M. Bonnefoy","Simon Petrus","Aarynn L. Carter","Élodie Choquet","Sasha Hinkley","Kimberly Ward-Duong","Jarron Leisenring","Maxwell A. Millar‐Blanchaer","Laurent A. Pueyo","Shrishmoy Ray","Steph Sallum"],"author_count":100,"year":2023,"published":"2023-03-01","venue":"The Astrophysical Journal Letters","cited_by":182,"doi":"10.3847/2041-8213/acb04a","arxiv_id":"2209.00620","nct_id":null,"source_url":"https://doi.org/10.3847/2041-8213/acb04a","archive_url":"https://space-kitty.com/papers/arxiv:2209.00620","updated":"2024-07-04","pmid":null,"pmcid":null,"openalex_id":"W4360613104","pdf_url":"https://iopscience.iop.org/article/10.3847/2041-8213/acb04a/pdf","abstract":"We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a $<$20 M$_\\mathrm{Jup}$ widely separated ($\\sim$8\\arcsec, a = 150 au), young, planetary-mass companion that shares photometric colors and spectroscopic features with the directly imaged exoplanets HR 8799 c, d, and e. As an L-to-T transition object, VHS 1256 b exists along the region of the color-magnitude diagram where substellar atmospheres transition from cloudy to clear. We observed VHS 1256~b with \\textit{JWST}'s NIRSpec IFU and MIRI MRS modes for coverage from 1 $μ$m to 20 $μ$m at resolutions of $\\sim$1,000 - 3,700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium are observed in several portions of the \\textit{JWST} spectrum based on comparisons from template brown dwarf spectra, molecular opacities, and atmospheric models. The spectral shape of VHS 1256 b is influenced by disequilibrium chemistry and clouds. We directly detect silicate clouds, the first such detection reported for a planetary-mass companion.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:2208.11692","kind":"article","title":"Identification of carbon dioxide in an exoplanet atmosphere","authors":["JWST Transiting Exoplanet Community Early Release Science Team","Eva-Maria Ahrer","Lili Alderson","Natalie M. Batalha","Natasha E. Batalha","Jacob L. Bean","Thomas G. Beatty","Taylor James Bell","Björn Benneke","Zachory K. Berta-Thompson","Aarynn L. Carter","Ian J. M. Crossfield","Néstor Espinoza","Adina D. Feinstein","Jonathan J. Fortney","Neale P. Gibson","Jayesh Goyal","Eliza M.-R. Kempton","James Kirk","Laura Kreidberg","Mercedes López‐Morales","Michael R. Line","Joshua D. Lothringer","Sarah E. Moran","Sagnick Mukherjee"],"author_count":100,"year":2022,"published":"2022-09-02","venue":"Nature","cited_by":197,"doi":"10.1038/s41586-022-05269-w","arxiv_id":"2208.11692","nct_id":null,"source_url":"https://doi.org/10.1038/s41586-022-05269-w","archive_url":"https://space-kitty.com/papers/arxiv:2208.11692","updated":"2022-08-24","pmid":"36055338","pmcid":null,"openalex_id":"W4294243316","pdf_url":"https://www.nature.com/articles/s41586-022-05269-w.pdf","abstract":"Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (i.e., elements heavier than helium, also called \"metallicity\"), and thus formation processes of the primary atmospheres of hot gas giants. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2 but have not yielded definitive detections due to the lack of unambiguous spectroscopic identification. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science Program (ERS). The data used in this study span 3.0 to 5.5 μm in wavelength and show a prominent CO2 absorption feature at 4.3 μm (26σ significance). The overall spectrum is well matched by one-dimensional, 10x solar metallicity models that assume radiative-convective-thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide, and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 μm that is not reproduced by these models.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1303.7079","kind":"article","title":"3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability, and habitability","authors":["Jérémy Leconte","F. Forget","Benjamin Charnay","Robin Wordsworth","Franck Selsis","Ehouarn Millour","Aymeric Spiga"],"author_count":7,"year":2013,"published":"2013-04-16","venue":"Astronomy and Astrophysics","cited_by":234,"doi":"10.1051/0004-6361/201321042","arxiv_id":"1303.7079","nct_id":null,"source_url":"https://doi.org/10.1051/0004-6361/201321042","archive_url":"https://space-kitty.com/papers/arxiv:1303.7079","updated":"2013-03-28","pmid":null,"pmcid":null,"openalex_id":"W2007661833","pdf_url":"https://arxiv.org/pdf/1303.7079","abstract":"The inner edge of the classical habitable zone is often defined by the critical flux needed to trigger the runaway greenhouse instability. This 1D notion of a critical flux, however, may not be so relevant for inhomogeneously irradiated planets, or when the water content is limited (land planets). Here, based on results from our 3D global climate model, we find that the circulation pattern can shift from super-rotation to stellar/anti stellar circulation when the equatorial Rossby deformation radius significantly exceeds the planetary radius. Using analytical and numerical arguments, we also demonstrate the presence of systematic biases between mean surface temperatures or temperature profiles predicted from either 1D or 3D simulations. Including a complete modeling of the water cycle, we further demonstrate that for land planets closer than the inner edge of the classical habitable zone, two stable climate regimes can exist. One is the classical runaway state, and the other is a collapsed state where water is captured in permanent cold traps. We identify this \"moist\" bistability as the result of a competition between the greenhouse effect of water vapor and its condensation. We also present synthetic spectra showing the observable signature of these two states. Taking the example of two prototype planets in this regime, namely Gl581c and HD85512b, we argue that they could accumulate a significant amount of water ice at their surface. If such a thick ice cap is present, gravity driven ice flows and geothermal flux should come into play to produce long-lived liquid water at the edge and/or bottom of the ice cap. Consequently, the habitability of planets at smaller orbital distance than the inner edge of the classical habitable zone cannot be ruled out. Transiting planets in this regime represent promising targets for upcoming observatories like EChO and JWST.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:2309.07047","kind":"article","title":"Atmospheric Reconnaissance of TRAPPIST-1 b with JWST/NIRISS: Evidence for Strong Stellar Contamination in the Transmission Spectra","authors":["Olivia Lim","Björn Benneke","René Doyon","Ryan J. MacDonald","Caroline Piaulet","Étienne Artigau","Louis-Philippe Coulombe","Michael Radica","Alexandrine L’Heureux","Loïc Albert","Benjamin V. Rackham","Julien de Wit","Salma Salhi","Pierre-Alexis Roy","Laura Flagg","Marylou Fournier-Tondreau","Jake Taylor","Neil J. Cook","David Lafreniére","Nicolas B. Cowan","Lisa Kaltenegger","Jason F. Rowe","Néstor Espinoza","Lisa Dang","Antoine Darveau-Bernier"],"author_count":25,"year":2023,"published":"2023-09-01","venue":"The Astrophysical Journal Letters","cited_by":175,"doi":"10.3847/2041-8213/acf7c4","arxiv_id":"2309.07047","nct_id":null,"source_url":"https://doi.org/10.3847/2041-8213/acf7c4","archive_url":"https://space-kitty.com/papers/arxiv:2309.07047","updated":"2023-09-13","pmid":null,"pmcid":null,"openalex_id":"W4386969607","pdf_url":"https://arxiv.org/pdf/2309.07047","abstract":"TRAPPIST-1 is a nearby system of seven Earth-sized, temperate, rocky exoplanets transiting a Jupiter-sized M8.5V star, ideally suited for in-depth atmospheric studies. Each TRAPPIST-1 planet has been observed in transmission both from space and from the ground, confidently rejecting cloud-free, hydrogen-rich atmospheres. Secondary eclipse observations of TRAPPIST-1 b with JWST/MIRI are consistent with little to no atmosphere given the lack of heat redistribution. Here we present the first transmission spectra of TRAPPIST-1 b obtained with JWST/NIRISS over two visits. The two transmission spectra show moderate to strong evidence of contamination from unocculted stellar heterogeneities, which dominates the signal in both visits. The transmission spectrum of the first visit is consistent with unocculted starspots and the second visit exhibits signatures of unocculted faculae. Fitting the stellar contamination and planetary atmosphere either sequentially or simultaneously, we confirm the absence of cloud-free hydrogen-rich atmospheres, but cannot assess the presence of secondary atmospheres. We find that the uncertainties associated with the lack of stellar model fidelity are one order of magnitude above the observation precision of 89 ppm (combining the two visits). Without affecting the conclusion regarding the atmosphere of TRAPPIST-1 b, this highlights an important caveat for future explorations, which calls for additional observations to characterize stellar heterogeneities empirically and/or theoretical works to improve model fidelity for such cool stars. This need is all the more justified as stellar contamination can affect the search for atmospheres around the outer, cooler TRAPPIST-1 planets for which transmission spectroscopy is currently the most efficient technique.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":"cc-by","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1909.04642","kind":"article","title":"Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b","authors":["Björn Benneke","Ian Wong","Caroline Piaulet","Heather A. Knutson","Joshua Lothringer","Caroline V. Morley","Ian J. M. Crossfield","Peter Gao","Thomas P. Greene","Courtney Dressing","Diana Dragomir","Andrew W. Howard","Peter R. McCullough","Eliza M. -R. Kempton","Jonathan J. Fortney","Jonathan Fraine"],"author_count":16,"year":2019,"published":"2019-09-10","venue":"ApJL, 887, L14 (2019)","cited_by":298,"doi":"10.3847/2041-8213/ab59dc","arxiv_id":"1909.04642","nct_id":null,"source_url":"https://arxiv.org/abs/1909.04642","archive_url":"https://space-kitty.com/papers/arxiv:1909.04642","updated":"2019-12-12","pmid":null,"pmcid":null,"openalex_id":"W2995360675","pdf_url":"https://arxiv.org/pdf/1909.04642","abstract":"Results from the Kepler mission indicate that the occurrence rate of small planets ($<3$ $R_\\oplus$) in the habitable zone of nearby low-mass stars may be as high as 80%. Despite this abundance, probing the conditions and atmospheric properties on any habitable-zone planet is extremely difficult and has remained elusive to date. Here, we report the detection of water vapor and the likely presence of liquid and icy water clouds in the atmosphere of the $2.6$ $R_\\oplus$ habitable-zone planet K2-18b. The simultaneous detection of water vapor and clouds in the mid-atmosphere of K2-18b is particularly intriguing because K2-18b receives virtually the same amount of total insolation from its host star ($1368_{-107}^{+114}$ W m$^{-2}$) as the Earth receives from the Sun (1361 W m$^{-2}$), resulting in the right conditions for water vapor to condense and explain the detected clouds. In this study, we observed nine transits of K2-18b using HST/WFC3 in order to achieve the necessary sensitivity to detect the water vapor, and we supplement this data set with Spitzer and K2 observations to obtain a broader wavelength coverage. While the thick hydrogen-dominated envelope we detect on K2-18b means that the planet is not a true Earth analog, our observations demonstrate that low-mass habitable-zone planets with the right conditions for liquid water are accessible with state-of-the-art telescopes.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["astro-ph.EP","astro-ph.IM"],"details":null,"provenance":"arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1409.7594","kind":"article","title":"Transmission spectral properties of clouds for hot Jupiter exoplanets","authors":["Hannah R. Wakeford","David K. Sing"],"author_count":2,"year":2014,"published":"2014-09-30","venue":"Astronomy and Astrophysics","cited_by":231,"doi":"10.1051/0004-6361/201424207","arxiv_id":"1409.7594","nct_id":null,"source_url":"https://doi.org/10.1051/0004-6361/201424207","archive_url":"https://space-kitty.com/papers/arxiv:1409.7594","updated":"2014-09-30","pmid":null,"pmcid":null,"openalex_id":"W2168403955","pdf_url":"https://www.aanda.org/articles/aa/pdf/2015/01/aa24207-14.pdf","abstract":"Clouds have an important role in the atmospheres of planetary bodies. It is expected that, like all the planetary bodies in our solar system, exoplanet atmospheres will also have substantial cloud coverage, and evidence is mounting for clouds in a number of hot Jupiters. In order to better characterise planetary atmospheres we need to consider the effects these clouds will have on the observed broadband transmission spectra. Here we examine the expected cloud condensate species for hot Jupiter exoplanets and the effects of various grain sizes and distributions on the resultant transmission spectra from the optical to infrared, which can be used as a broad framework when interpreting exoplanet spectra. We note that significant infrared absorption features appear in the computed transmission spectrum, the result of vibrational modes between the key species in each condensate, which can potentially be very constraining. While it may be hard to differentiate between individual condensates in the broad transmission spectra, it may be possible to discern different vibrational bonds, which can distinguish between cloud formation scenarios such as condensate clouds or photochemically generated species. Vibrational mode features are shown to be prominent when the clouds are composed of small sub-micron sized particles and can be associated with an accompanying optical scattering slope. These infrared features have potential implications for future exoplanetary atmosphere studies conducted with JWST, where such vibrational modes distinguishing condensate species can be probed at longer wavelengths.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"arxiv:1909.05218","kind":"article","title":"Water vapour in the atmosphere of the habitable-zone eight Earth-mass planet K2-18 b","authors":["Angelos Tsiaras","Ingo P. Waldmann","Giovanna Tinetti","Jonathan Tennyson","Sergey N. Yurchenko"],"author_count":5,"year":2019,"published":"2019-09-11","venue":"Nature Astronomy","cited_by":284,"doi":"10.1038/s41550-019-0878-9","arxiv_id":"1909.05218","nct_id":null,"source_url":"https://arxiv.org/abs/1909.05218","archive_url":"https://space-kitty.com/papers/arxiv:1909.05218","updated":"2019-09-11","pmid":null,"pmcid":null,"openalex_id":"W2972809076","pdf_url":"https://arxiv.org/pdf/1909.05218","abstract":"In the past decade, observations from space and ground have found H$_2$O to be the most abundant molecular species, after hydrogen, in the atmospheres of hot, gaseous, extrasolar planets. Being the main molecular carrier of oxygen, H$_2$O is a tracer of the origin and the evolution mechanisms of planets. For temperate, terrestrial planets, the presence of H$_2$O is of great significance as an indicator of habitable conditions. Being small and relatively cold, these planets and their atmospheres are the most challenging to observe, and therefore no atmospheric spectral signatures have so far been detected. Super-Earths -- planets lighter than ten M$_\\oplus$ -- around later-type stars may provide our first opportunity to study spectroscopically the characteristics of such planets, as they are best suited for transit observations. Here we report the detection of an H$_2$O spectroscopic signature in the atmosphere of \\planet\\ -- an eight M$_\\oplus$ planet in the habitable-zone of an M-dwarf -- with high statistical confidence (ADI = 5.0, $\\sim$3.6$σ$). In addition, the derived mean molecular weight suggests an atmosphere still containing some hydrogen. The observations were recorded with the Hubble Space Telescope/WFC3 camera, and analysed with our dedicated, publicly available, algorithms. While the suitability of M-dwarfs to host habitable worlds is still under discussion, \\planet\\ offers an unprecedented opportunity to get insight into the composition and climate of habitable-zone planets.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["astro-ph.EP"],"details":null,"provenance":"arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."},{"id":"doi:10.1051/0004-6361/201321042/pdf","kind":"article","title":"3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability, and habitability","authors":["Jérémy Leconte","F. Forget","Benjamin Charnay","Robin Wordsworth","Franck Selsis","Ehouarn Millour","Aymeric Spiga"],"author_count":7,"year":2013,"published":"2013-06-05","venue":"Springer Link (Chiba Institute of Technology)","cited_by":205,"doi":"10.1051/0004-6361/201321042/pdf","arxiv_id":null,"nct_id":null,"source_url":"https://www.aanda.org/10.1051/0004-6361/201321042/pdf","archive_url":"https://space-kitty.com/papers/doi:10.1051/0004-6361/201321042/pdf","updated":null,"pmid":null,"pmcid":null,"openalex_id":"W3100573144","pdf_url":null,"abstract":null,"abstract_license":null,"license":null,"is_open_access":false,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex","attribution":"Metadata and citation counts: OpenAlex (CC0)."},{"id":"arxiv:2108.10888","kind":"article","title":"Habitability and Biosignatures of Hycean Worlds","authors":["Nikku Madhusudhan","Anjali A. A. Piette","Savvas Constantinou"],"author_count":3,"year":2021,"published":"2021-08-26","venue":"The Astrophysical Journal","cited_by":166,"doi":"10.3847/1538-4357/abfd9c","arxiv_id":"2108.10888","nct_id":null,"source_url":"https://doi.org/10.3847/1538-4357/abfd9c","archive_url":"https://space-kitty.com/papers/arxiv:2108.10888","updated":"2021-09-01","pmid":null,"pmcid":null,"openalex_id":"W3195875890","pdf_url":"https://iopscience.iop.org/article/10.3847/1538-4357/abfd9c/pdf","abstract":"We investigate a new class of habitable planets composed of water-rich interiors with massive oceans underlying H2-rich atmospheres, referred to here as Hycean worlds. With densities between those of rocky super-Earths and more extended mini-Neptunes, Hycean planets can be optimal candidates in the search for exoplanetary habitability and may be abundant in the exoplanet population. We investigate the bulk properties (masses, radii, and temperatures), potential for habitability, and observable biosignatures of Hycean planets. We show that Hycean planets can be significantly larger compared to previous considerations for habitable planets, with radii as large as 2.6 Earth radii (2.3 Earth radii) for a mass of 10 Earth masses (5 Earth masses). We construct the Hycean habitable zone (HZ), considering stellar hosts from late M to sun-like stars, and find it to be significantly wider than the terrestrial-like HZ. While the inner boundary of the Hycean HZ corresponds to equilibrium temperatures as high as ~500 K for late M dwarfs, the outer boundary is unrestricted to arbitrarily large orbital separations. Our investigations include tidally locked `Dark Hycean' worlds that permit habitable conditions only on their permanent nightsides and `Cold Hycean' worlds that see negligible irradiation. Finally, we investigate the observability of possible biosignatures in Hycean atmospheres. We find that a number of trace terrestrial biomarkers which may be expected to be present in Hycean atmospheres would be readily detectable using modest observing time with the James Webb Space Telescope (JWST). We identify a sizable sample of nearby potential Hycean planets that can be ideal targets for such observations in search of exoplanetary biosignatures.","abstract_license":"CC0-1.0 (arXiv descriptive metadata)","license":null,"is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":["Stellar, planetary, and galactic studies"],"details":null,"provenance":"openalex+arxiv","attribution":"Abstract: arXiv descriptive metadata (CC0). Thank you to arXiv for use of its open access interoperability. This service was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv."}],"next":"https://space-kitty.com/api/v1/topics/exoplanets-biosignatures/papers?sort=top&limit=25&offset=25"}