# Exoplanets & Biosignatures Domain: Astrophysics & Cosmology · 247 papers indexed · newest 2026-10-28 JWST exoplanet atmospheres, temperate sub-Neptunes and rocky worlds, and the debate over claimed biosignature gases. Key concepts: exoplanet atmosphere, biosignature, JWST transmission spectrum, habitable zone, sub-Neptune, K2-18 b ## Most influential - **[Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM](https://space-kitty.com/papers/arxiv:2211.10487)**. Zafar Rustamkulov, David K. Sing, S. Mukherjee et al. · 2023 · Nature (arXiv:2211.10487 · doi:10.1038/s41586-022-05677-y · 328 citations). Source: > 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 exopla… - **[The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets](https://space-kitty.com/papers/arxiv:1711.05691)**. Benjamin V. Rackham, Dániel Apai, Mark S. Giampapa · 2018 · The Astrophysical Journal (arXiv:1711.05691 · doi:10.3847/1538-4357/aaa08c · 421 citations). Source: > 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 l… - **[Carbon-bearing Molecules in a Possible Hycean Atmosphere](https://space-kitty.com/papers/arxiv:2309.05566)**. Nikku Madhusudhan, Subhajit Sarkar, Savvas Constantinou et al. · 2023 · The Astrophysical Journal Letters (arXiv:2309.05566 · doi:10.3847/2041-8213/acf577 · 279 citations). Source: > 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 accessib… - **[CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST](https://space-kitty.com/papers/arxiv:1511.05528)**. Thomas P. Greene, Michael R. Line, Cezar Montero et al. · 2016 · The Astrophysical Journal (arXiv:1511.05528 · doi:10.3847/0004-637x/817/1/17 · 385 citations). Source: > 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… - **[Early Release Science of the exoplanet WASP-39b with JWST NIRSpec G395H](https://space-kitty.com/papers/doi:10.1038/s41586-022-05591-3)**. Lili Alderson, Hannah R. Wakeford, Munazza K. Alam et al. · 2023 · Nature (doi:10.1038/s41586-022-05591-3 · 276 citations). Source: > 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 (… > _Abstract excerpt by Lili Alderson et al., CC-BY, https://doi.org/10.1038/s41586-022-05591-3; truncated._ - **[Photochemically produced SO2 in the atmosphere of WASP-39b](https://space-kitty.com/papers/doi:10.1038/s41586-023-05902-2)**. Shang‐Min Tsai, Elspeth K. H. Lee, Diana Powell et al. · 2023 · Nature (doi:10.1038/s41586-023-05902-2 · 266 citations). Source: > 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 … > _Abstract excerpt by Shang‐Min Tsai et al., CC-BY, https://doi.org/10.1038/s41586-023-05902-2; truncated._ - **[Planetary Spectrum Generator: An accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets](https://space-kitty.com/papers/arxiv:1803.02008)**. G. L. Villanueva, Michael D. Smith, Silvia Protopapa et al. · 2018 · Journal of Quantitative Spectroscopy and Radiative Transfer (arXiv:1803.02008 · doi:10.1016/j.jqsrt.2018.05.023 · 328 citations). Source: > 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 p… - **[Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST](https://space-kitty.com/papers/arxiv:2303.14849)**. Thomas P. Greene, Taylor James Bell, Elsa Ducrot et al. · 2023 · Nature (arXiv:2303.14849 · doi:10.1038/s41586-023-05951-7 · 244 citations). Source: > 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 irradiati… - **[CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST](https://space-kitty.com/papers/openalex:W3101474964)**. Thomas P. Greene, Michael R. Line, Cezar Montero et al. · 2016 · eScholarship (California Digital Library) (308 citations). Source: - **[Exoplanet Atmospheres](https://space-kitty.com/papers/arxiv:1005.4037)**. S. Seager, D. Deming · 2010 · Annual Review of Astronomy and Astrophysics (arXiv:1005.4037 · doi:10.1146/annurev-astro-081309-130837 · 435 citations). Source: > 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 temperatu… - **[Observations of Transiting Exoplanets with the James Webb Space Telescope (JWST)](https://space-kitty.com/papers/doi:10.1086/679566)**. Charles Beichman, Bjoern Benneke, Heather A. Knutson et al. · 2014 · Publications of the Astronomical Society of the Pacific (doi:10.1086/679566 · 283 citations). Source: - **[No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c](https://space-kitty.com/papers/arxiv:2306.10150)**. Sebastian Zieba, Laura Kreidberg, Elsa Ducrot et al. · 2023 · Nature (arXiv:2306.10150 · doi:10.1038/s41586-023-06232-z · 220 citations). Source: > 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 th… - **[New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI](https://space-kitty.com/papers/arxiv:2504.12267)**. Nikku Madhusudhan, Savvas Constantinou, Måns Holmberg et al. · 2025 · The Astrophysical Journal Letters (arXiv:2504.12267 · doi:10.3847/2041-8213/adc1c8 · 82 citations). Source: > 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 … - **[The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST](https://space-kitty.com/papers/arxiv:1905.07070)**. Jacob Lustig‐Yaeger, Victoria S. Meadows, Andrew Lincowski · 2019 · The Astronomical Journal (arXiv:1905.07070 · doi:10.3847/1538-3881/ab21e0 · 252 citations). Source: > 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 dete… - **[Early Release Science of the exoplanet WASP-39b with JWST NIRCam](https://space-kitty.com/papers/doi:10.1038/s41586-022-05590-4)**. Eva-Maria Ahrer, Kevin B. Stevenson, Megan Mansfield et al. · 2023 · Nature (doi:10.1038/s41586-022-05590-4 · 198 citations). Source: > 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, w… > _Abstract excerpt by Eva-Maria Ahrer et al., CC-BY, https://doi.org/10.1038/s41586-022-05590-4; truncated._ ## Newest - **[Reconciling Giant Impacts with the Radius Valley: The Role of Silicate-Hydrogen Miscibility for Sub-Neptunes](https://space-kitty.com/papers/arxiv:2610.38852)**. Eva Zlimen, Hilke E. Schlichting, James G. Rogers · 2026 (arXiv:2610.38852). Source: - **[Retention of primordial atmospheres through giant impacts](https://space-kitty.com/papers/arxiv:2610.36446)**. Darius Modirrousta-Galian, Jun Korenaga · 2026 (arXiv:2610.36446 · doi:10.1038/s41550-026-03006-1). Source: - **[Revisiting the Photometric Modulation Amplitudes of Kepler Planet Hosts: A Confounder-Adjusted Test of Stellar Spin-Orbit Alignment](https://space-kitty.com/papers/arxiv:2610.36664)**. Kento Masuda, Subo Dong · 2026 (arXiv:2610.36664). Source: - **[Revisiting Sub-Neptune Population Synthesis: The Role of Core Luminosity in Boil-off, Photoevaporation, and the Radius Distribution](https://space-kitty.com/papers/arxiv:2610.37789)**. Yao Tang, Jonathan J. Fortney, Natalie Batalha et al. · 2026 (arXiv:2610.37789). Source: - **[Measuring masses of transiting Earth-like planets: first insights from the PLATO RV data challenge](https://space-kitty.com/papers/arxiv:2610.36201)**. M. Cretignier, N. C. Hara, S. Aigrain et al. · 2026 · MNRAS, 551, 2026 (arXiv:2610.36201 · doi:10.1093/mnras/stag1543). Source: - **[Proposed optimal targets for a Lazuli ExtraSolar Coronagraph reflected starlight exoplanet campaign](https://space-kitty.com/papers/arxiv:2610.31286)**. Logan A. Pearce, Ewan Douglas · 2026 (arXiv:2610.31286). Source: - **[A Headwind-like Helium Outflow from TOI-3884b](https://space-kitty.com/papers/arxiv:2610.31492)**. Joe P. Ninan, Jessica Libby-Roberts, Suvrath Mahadevan et al. · 2026 (arXiv:2610.31492). Source: - **[The Pandora SmallSat: Target Selection and Early Science](https://space-kitty.com/papers/arxiv:2610.30028)**. Emily A. Gilbert, Elisa V. Quintana, Jessie L. Dotson et al. · 2026 · Space Telescopes and Instrumentation: Optical, Infrared, and Millimeter Wave (arXiv:2610.30028 · doi:10.1117/12.3104260). Source: - **[The Pandora SmallSat: post-launch operations and mission update](https://space-kitty.com/papers/arxiv:2610.30372)**. Trevor O. Foote, Elisa V. Quintana, Jessie L. Dotson et al. · 2026 · Space Telescopes and Instrumentation: Optical, Infrared, and Millimeter Wave (arXiv:2610.30372 · doi:10.1117/12.3103034). Source: - **[Two Validated Planets and 179 Candidates From a TESS Faint Star Transit Search in the ULTRASAT Fields](https://space-kitty.com/papers/arxiv:2610.28518)**. Matthew Lastovka, Thomas Barclay, Robert F. Wilson et al. · 2026 (arXiv:2610.28518). Source: --- Space Kitty Archive · https://space-kitty.com · API: https://space-kitty.com/api/v1 · MCP: https://space-kitty.com/mcp · Premium: $0.20/request via x402 (Base Sepolia (testnet)). Metadata: arXiv (CC0), OpenAlex (CC0), Europe PMC (CC BY/CC0 works), ClinicalTrials.gov.