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arxiv: 2605.17803 · v1 · pith:GN4AG7XHnew · submitted 2026-05-18 · 🌌 astro-ph.EP

A Hycean Interpretation of K2-18b Supported by Photochemical Atmospheric Compositional

Takuya Fujisawa , Masashi Shimada , Tatsuya Yoshida , Kiyoshi Kuramoto This is my paper

Pith reviewed 2026-05-20 01:14 UTC · model grok-4.3

classification 🌌 astro-ph.EP
keywords K2-18bHycean planettransmission spectroscopyphotochemical modelingJWSTsub-Neptune atmospherecarbon monoxideliquid ocean
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The pith

Hycean atmospheres with a 1-bar H2 envelope, percent-level CH4 and CO, and CO2 at 10^{-3} to 10^{-2} reproduce the JWST spectra of K2-18b without DMS.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines whether Hycean configurations, featuring a liquid water ocean beneath a thin hydrogen atmosphere, can account for the transmission spectra of the sub-Neptune K2-18b collected by JWST instruments. Using photochemical models to compute gas abundances and radiative-convective calculations to ensure stable climates, the authors find that specific mixtures of H2, CH4, CO, and CO2 fit the observed data from 0.8 to 5.2 microns. This approach avoids invoking additional species such as dimethyl sulfide. A reader would care because it keeps open the possibility of liquid oceans on this world and similar sub-Neptunes, rather than defaulting to mini-Neptune interpretations with no surface liquid. The modeling also highlights that photochemical networks and mass balance naturally produce the required compositions and spectral features.

Core claim

Hycean models with a 1 bar H2 envelope, percent-level CH4 and CO, and CO2 buffered at ~10^{-3}-10^{-2} reproduce the NIRISS and NIRSpec spectra from 0.8 to 5.2 μm without invoking DMS or other additional species. Photochemical simulations show that H2-CH4-H2O networks generically drive CO to mixing ratios of order 1-2 %. Mass-balance arguments imply that a ~1 bar H2 envelope with percent-level CH4 requires interior replenishment on gigayear timescales, and the resulting vertical gradients naturally generate flat, CH4-dominated plateaux in transmission.

What carries the argument

One-dimensional photochemical modeling of H2-CH4-H2O networks coupled to radiative-convective equilibrium calculations that avoid runaway greenhouse states, then used for forward modeling of transmission spectra.

If this is right

  • Liquid oceans remain stable over wide ranges of temperature and pressure in these setups.
  • H2-CH4-H2O photochemical networks produce CO at 1-2% mixing ratios as a generic outcome.
  • Interior replenishment of CH4 on gigayear timescales is required to maintain the envelope.
  • Vertical abundance gradients create flat CH4-dominated plateaux in the transmission spectrum.
  • Existing CO and CO2 constraints alone cannot yet exclude Hycean interpretations.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Tighter measurements of the 4-5 μm CO feature in future JWST cycles could directly test the predicted 1-2% abundance.
  • The same modeling approach might apply to other sub-Neptunes showing similar flat transmission spectra.
  • Adding hazes or trace condensables in follow-up calculations would show how robust the current spectral match remains.
  • If correct, the result broadens the pool of targets where liquid-water oceans could be searched for using transmission data.

Load-bearing premise

The atmosphere is a pure H2-CH4-H2O mixture over a liquid ocean with no hazes or other condensables, and the 1-bar H2 envelope stays stable against escape or mixing with deeper layers.

What would settle it

High-precision spectra in the 4-5 μm region that show CO abundances well below 1% or require strong additional absorbers inconsistent with the predicted CH4-CO-CO2 balance would falsify the Hycean fit.

Figures

Figures reproduced from arXiv: 2605.17803 by Kiyoshi Kuramoto, Masashi Shimada, Takuya Fujisawa, Tatsuya Yoshida.

Figure 1
Figure 1. Figure 1: Assumed spectrum based on the observation for a M2.5V dwarf star GJ176 (blue line). The intensity at each wavelength is converted to the value correspond to the orbit of K2-18b. For comparison, the solar spectrum is shown by the red line, scaled to match the total bolometric flux. The vertical axis represents λFλ, meaning that the area under the curve in this logarithmic plot is proportional to the in￾tegr… view at source ↗
Figure 2
Figure 2. Figure 2: Pressure–temperature (P–T) profiles for the K2-18b atmosphere. This panel shows the Hycean K2-18b P–T profile adopted in this work: the surface temperature is 328 K and the surface pressure is 1 bar. The troposphere fol￾lows an adiabatic temperature gradient up to the tropopause, above which the stratosphere is isothermal at 215 K. and indicative of an atmosphere in which the cold trap efficiently limits t… view at source ↗
Figure 3
Figure 3. Figure 3: Conceptual illustration of a light ray passing through the planetary atmosphere at altitude z from the planetary surface. The blue region represents the planet, and the light blue region represents the atmosphere. The red arrow indicates a light path passing through the atmosphere. The altitude of the light path from the planetary surface is denoted by z, and coordinates s are taken along the path. The ori… view at source ↗
Figure 4
Figure 4. Figure 4: Graph of absorption coefficients used for calculating the transit depth. For improved clarity, a moving average has been applied to the absorption cross-sections. DMS data was obtained from HITRAN absorption cross section, considering N2 atmosphere and a temperature-pressure broadening at 298 K and 1 bar. Information for other absorption coefficients was obtained from HITRAN HAPI, considering an H2 backgro… view at source ↗
Figure 5
Figure 5. Figure 5: Altitude distribution of mixing ratios for the CO2-bearing reference case obtained from our photochemical calculations. In addition to the initial chemical species, en￾hanced concentrations of CO, C2H6, and C2H2 are observed, with CO reaching mixing ratios of order 2% and C2H6 and C2H2 reaching ∼ 10−3 near an altitude of 600 km. A sharp decrease in CH4 occurs around the same altitude, where the C2H2 concen… view at source ↗
Figure 6
Figure 6. Figure 6: Diagram of the dominant chemical reaction pathways in our photochemical network. Bold text indicates the initial chemical species. Species shaded in light orange correspond to those plotted in [PITH_FULL_IMAGE:figures/full_fig_p012_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Graph showing the reaction rates of major CH4 decomposition reactions in the region of CH4 concentration change. Reactions involving C2 radicals produced by the photodissociation of C2H6 are dominant. the ocean to store oxidised carbon at fixed atmospheric CO2 partial pressure. The factor β effectively encapsu￾lates the dependence of carbonate speciation on ocean pH: for present-day Earth-like mildly alkal… view at source ↗
Figure 8
Figure 8. Figure 8: Relationships between the prescribed stratospheric H2O mixing ratio, the CO2 mass flux, and the resulting atmospheric CO2 mixing ratio in the CO2-free experiments. Left panel: CO2 mixing ratio accumulated in the atmosphere over a timescale of 3 Gyr as a function of the stratospheric H2O mixing ratio in the photochemical experiments lower-boundary-CO2-free experiments. Right panel: atmospheric CO2 mixing ra… view at source ↗
Figure 9
Figure 9. Figure 9: Transit spectra of K2-18b in the NIRISS SOSS wavelength range (0.8–2.8 µm). The figure compares model spectra (light purple lines) with observed data points including error bars. In the upper panel, we use the number density profiles of H2, CH4, CO, CO2, C2H2, and C2H6 obtained from our photochemical calculations. In the lower panel, we instead assume vertically uniform number densities for all species. Fo… view at source ↗
Figure 10
Figure 10. Figure 10: Left: Posterior distributions of the wavelength-independent offset ∆off for each reduction, derived from the CH4-dominated 2.8–4.0 µm band using Equation (7). Shaded regions indicate the 1σ and 2σ credible intervals listed in [PITH_FULL_IMAGE:figures/full_fig_p016_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Posterior probability distributions for the CO (left) and CO2 (right) volume mixing ratios, p(XCO) and p(XCO2 ), for the five reductions considered in this work. Each curve is plotted as a step histogram in log10 mixing ratio and represents a probability density in u = log10 X normalised such that R p(u) du = 1. These densities are obtained from the discrete posteriors on the log-spaced grid by dividing b… view at source ↗
Figure 12
Figure 12. Figure 12: Surface pressure–albedo diagram for H2-rich atmospheres under the incident flux of K2-18b. The hor￾izontal axis shows the surface pressure, and the vertical axis shows the planetary Bond albedo. Solid curves denote isotherms of surface temperature, colour-coded according to the scale bar on the right-hand side. The dashed curve marks the approximate boundary beyond which no radiative–con￾vective equilibri… view at source ↗
Figure 13
Figure 13. Figure 13: Surface pressure–temperature diagram with contours of the stratospheric H2O mixing ratio. The hori￾zontal axis shows the surface pressure, and the vertical axis shows the surface temperature. Solid curves indicate lines of constant H2O mixing ratio in the stratosphere, evaluated at the cold trap near the tropopause. climates. A more detailed discussion of how these cli￾matic constraints relate to the CO2 … view at source ↗
Figure 14
Figure 14. Figure 14: Comparison of best-fit Hycean model spectra for the exoTEDRF reduction in the CO/CO2-sensitive region. Left: R≈55 binning using the wavelength grid adopted by Madhusudhan et al. (2023), applied to the exoTEDRF spectra. Right: R≈100 binning constructed consistently from the native exoTEDRF pixel-level spectra and their associated uncertainties. In both panels the solid curves show the best-fit models withi… view at source ↗
Figure 15
Figure 15. Figure 15: Best-fit Hycean transmission spectrum for K2-18b compared with the combined JWST NIRISS SOSS and NIRSpec G395H data from the exoTEDRF reduction. The solid purple line shows the forward model computed using the photochemical profiles for H2, CH4, CO, CO2, C2H2, and C2H6 ( [PITH_FULL_IMAGE:figures/full_fig_p021_15.png] view at source ↗
read the original abstract

The nature of the sub-Neptune K2-18b is debated between Hycean and mini-Neptune interpretations. We test whether self-consistent Hycean atmospheres are compatible with current JWST transmission spectra by combining one-dimensional photochemical modelling, radiative--convective equilibrium calculations, and forward modelling of transmission spectra. We assume H2-CH4-H2O atmospheres over a liquid ocean, compute altitude-dependent abundances with a 1D photochemical model, and couple them to P-T profiles that avoid runaway greenhouse states. Using the CH4-dominated 2.8-4.0 $\mu$m band, we constrain wavelength-independent offsets between NIRISS SOSS and NIRSpec G395H for multiple reductions, and then scan grids of CO and CO2 scaling factors, weighted by the CH4-band offset posteriors, to evaluate oxidised-carbon abundances consistent with the 4-5 $\mu$m region. Radiative--convective calculations further map pressures and albedos that yield non-runaway climates. Over a wide range of temperatures and pressures, liquid oceans can exist, and Hycean models with a 1 bar H2 envelope, percent-level CH4 and CO, and CO2 buffered at $\sim 10^{-3}$-$10^{-2}$ reproduce the NIRISS and NIRSpec spectra from 0.8 to 5.2 $\mu$m without invoking DMS or other additional species. Our photochemical simulations show that H2-CH4-H2O networks generically drive CO to mixing ratios of order 1-2 %. Mass-balance arguments imply that a $\sim$1 bar H2 envelope with percent-level CH4 requires interior replenishment on gigayear timescales, and the resulting vertical gradients naturally generate flat, CH4-dominated plateaux in transmission. While mini-Neptune scenarios remain viable, our results show that Hycean configurations are likewise consistent with the data, and current CO and CO2 constraints alone are not yet sufficient to rule out Hycean interpretations of K2-18b.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 3 minor

Summary. The manuscript claims that self-consistent Hycean atmospheres (H2-CH4-H2O over a liquid ocean) with a 1 bar H2 envelope, percent-level CH4 and CO, and CO2 buffered at ~10^{-3}-10^{-2} reproduce the JWST NIRISS SOSS and NIRSpec G395H transmission spectra of K2-18b from 0.8 to 5.2 μm. This is shown via 1D photochemical modeling yielding ~1-2% CO, radiative-convective calculations for non-runaway P-T profiles, forward modeling of spectra, and use of the CH4 2.8-4.0 μm band to constrain wavelength-independent offsets between instruments before scanning CO/CO2 grids. The authors conclude that current CO/CO2 constraints do not rule out Hycean interpretations and that interior replenishment on Gyr timescales is implied by mass balance.

Significance. If the central claims hold, the work is significant for demonstrating that Hycean configurations are compatible with existing JWST data on K2-18b, thereby keeping both Hycean and mini-Neptune scenarios viable. The self-consistent coupling of photochemical networks to radiative-convective equilibrium and transmission spectra, together with the mass-balance arguments for envelope maintenance, provides a useful framework and falsifiable predictions for future observations. The explicit avoidance of runaway greenhouse states and the generic production of CO in H2-CH4-H2O networks are particular strengths.

major comments (3)
  1. [Abstract and §4] Abstract and the offset/grid procedure: The wavelength-independent offset between NIRISS SOSS and NIRSpec G395H is derived from the CH4-dominated 2.8-4.0 μm band and then used to weight the CO/CO2 scaling-factor grid; this data-driven adjustment means the claim that the models 'reproduce' the spectra is not fully independent of the target data, introducing a circularity risk that affects the evaluation of oxidized-carbon abundances in the 4-5 μm region.
  2. [Results] Results section: No quantitative goodness-of-fit metrics (e.g., χ², reduced χ², or posterior probabilities) or error bars on the model spectra are reported, making it impossible to assess objectively how well the Hycean models match the data relative to alternatives or to evaluate sensitivity to the chosen offset posteriors.
  3. [§3.1 and §6] §3.1 and §6: The assumption of a pure H2-CH4-H2O mixture with no hazes or additional condensables, together with the stability of the 1-bar H2 envelope against escape or mixing, is load-bearing for the flat CH4 plateau and spectral reproduction, yet no explicit test of haze yields from CH4 photochemistry or envelope stability is provided in the coupled radiative-convective + transmission calculations.
minor comments (3)
  1. [Title] The title appears truncated ('Supported by Photochemical Atmospheric Compositional'); consider completing it for clarity.
  2. [Throughout] Notation for mixing ratios and pressures should be made fully consistent (e.g., always using scientific notation such as 10^{-3} rather than mixing decimal and exponential forms).
  3. [Figures] Ensure all figures display data error bars, model uncertainty ranges, and explicit labels distinguishing the various CO/CO2 grid members.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their positive assessment of the work's significance and for the constructive major comments. We respond to each point below, indicating planned revisions where appropriate.

read point-by-point responses

  1. Referee: [Abstract and §4] The wavelength-independent offset between NIRISS SOSS and NIRSpec G395H is derived from the CH4-dominated 2.8-4.0 μm band and then used to weight the CO/CO2 scaling-factor grid; this data-driven adjustment means the claim that the models 'reproduce' the spectra is not fully independent of the target data, introducing a circularity risk that affects the evaluation of oxidized-carbon abundances in the 4-5 μm region.

    Authors: We thank the referee for noting this procedural detail. The offset is determined solely from the 2.8-4.0 μm interval where CH4 absorption dominates and CO/CO2 features contribute negligibly according to our forward models. This wavelength-independent shift aligns the two instrument reductions before the separate CO/CO2 grid evaluation is performed in the 4-5 μm region. Because the CH4 band is insensitive to the oxidized-carbon scaling factors, the procedure does not directly tune those abundances to the data. We will revise the abstract and §4 to state this spectral separation explicitly and add a short sensitivity test confirming that CO/CO2 conclusions are unchanged across the offset posterior range. revision: partial

  2. Referee: [Results] No quantitative goodness-of-fit metrics (e.g., χ², reduced χ², or posterior probabilities) or error bars on the model spectra are reported, making it impossible to assess objectively how well the Hycean models match the data relative to alternatives or to evaluate sensitivity to the chosen offset posteriors.

    Authors: We agree that quantitative metrics would strengthen the presentation. In the revised manuscript we will report χ² and reduced χ² values for the Hycean models against the observed spectra, together with uncertainty ranges on the model spectra propagated from the offset posteriors and parameter grids. This will permit direct comparison with alternative scenarios and clearer assessment of fit quality. revision: yes

  3. Referee: [§3.1 and §6] The assumption of a pure H2-CH4-H2O mixture with no hazes or additional condensables, together with the stability of the 1-bar H2 envelope against escape or mixing, is load-bearing for the flat CH4 plateau and spectral reproduction, yet no explicit test of haze yields from CH4 photochemistry or envelope stability is provided in the coupled radiative-convective + transmission calculations.

    Authors: We acknowledge that the haze-free and envelope-stability assumptions are central. Our photochemical network yields low higher-hydrocarbon production rates under the explored conditions, consistent with prior H2-rich atmosphere studies, but we did not insert explicit haze opacities into the coupled radiative-convective runs. Envelope stability is supported by the mass-balance arguments but lacks a dedicated escape calculation. We will expand §3.1 and §6 to discuss the photochemical haze yields, cite relevant literature on minimal haze formation, and note the stability assumption with supporting references while identifying a full escape analysis as a limitation for future work. revision: partial

Circularity Check

1 steps flagged

CH4-band offset fitting from data weights CO/CO2 grid, making full-spectrum reproduction dependent on target data

specific steps
  1. fitted input called prediction [Abstract]
    "Using the CH4-dominated 2.8-4.0 μm band, we constrain wavelength-independent offsets between NIRISS SOSS and NIRSpec G395H for multiple reductions, and then scan grids of CO and CO2 scaling factors, weighted by the CH4-band offset posteriors, to evaluate oxidised-carbon abundances consistent with the 4-5 μm region. ... Hycean models with a 1 bar H2 envelope, percent-level CH4 and CO, and CO2 buffered at ∼10^{-3}-10^{-2} reproduce the NIRISS and NIRSpec spectra from 0.8 to 5.2 μm without invoking DMS or other additional species."

    Offsets are fitted to the CH4 portion of the target spectra; these posteriors then weight the CO/CO2 grid evaluated on the adjacent 4-5 μm region. The final claim that the models reproduce the full 0.8-5.2 μm spectra is achieved after this data-driven adjustment and scaling rather than as an independent test of the assumed H2-CH4-H2O photochemical network and 1-bar envelope.

full rationale

The paper demonstrates compatibility of Hycean models with JWST spectra via photochemical abundances, radiative-convective P-T profiles, and forward modeling. The key step constrains inter-instrument offsets directly from the CH4 band in the observed data, then uses the resulting posteriors to weight a grid search over CO/CO2 scalings for the 4-5 μm region before claiming overall reproduction. This is a standard fitting procedure for model testing rather than a first-principles derivation or blind prediction, so the reproduction claim is partially data-dependent by construction. No self-citations, definitional loops, or imported uniqueness theorems appear in the provided text; the photochemical network and mass-balance arguments stand as independent content. The result is therefore self-contained against external benchmarks with only moderate circularity from the fitting chain.

Axiom & Free-Parameter Ledger

3 free parameters · 2 axioms · 0 invented entities

The central claim rests on several modeling choices whose justification is not supplied in the abstract: the assumption of a pure H2-CH4-H2O composition, the 1-bar H2 envelope mass, the absence of hazes or other condensables, and the use of wavelength-independent instrument offsets derived from the CH4 band itself.

free parameters (3)
  • wavelength-independent offset between NIRISS SOSS and NIRSpec G395H
    Derived from the CH4-dominated 2.8-4.0 μm band and then used to weight the CO/CO2 grid.
  • CO and CO2 scaling factors
    Scanned in a grid to match the 4-5 μm region after offset correction.
  • surface pressure and albedo
    Varied to find non-runaway P-T profiles that still allow a liquid ocean.
axioms (2)
  • domain assumption H2-CH4-H2O networks generically drive CO to mixing ratios of order 1-2 %
    Stated as a result of the photochemical simulations but not derived from first principles in the abstract.
  • domain assumption A ~1 bar H2 envelope with percent-level CH4 requires interior replenishment on gigayear timescales
    Invoked via mass-balance arguments without explicit calculation shown.

pith-pipeline@v0.9.0 · 5915 in / 1723 out tokens · 45898 ms · 2026-05-20T01:14:50.619702+00:00 · methodology

discussion (0)

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Works this paper leans on

39 extracted references · 39 canonical work pages

  1. [1]

    2019, ApJL, 887, L14, doi: 10.3847/2041-8213/ab59dc

    Benneke, B., Wong, I., Piaulet, C., & et al. 2019, ApJL, 887, L14, doi: 10.3847/2041-8213/ab59dc

    work page doi:10.3847/2041-8213/ab59dc 2019

  2. [2]

    F., Cooper, G., & Brion, C

    Chan, W. F., Cooper, G., & Brion, C. E. 1993, Chemical Physics, 170, 123, doi: 10.1016/0301-0104(93)80098-T

    work page doi:10.1016/0301-0104(93)80098-t 1993

  3. [3]

    J., Lovelock, J

    Charlson, R. J., Lovelock, J. E., Andreae, M. O., & Warren, S. G. 1987, Nature, 326, 655, doi: 10.1038/326655a0

    work page doi:10.1038/326655a0 1987

  4. [4]

    Chase, M. W. 1998, NIST-JANAF Thermochemical Tables, 4th Edition. https://www.nist.gov/publications/nist- janaf-thermochemical-tables-4th-edition

    work page 1998

  5. [5]

    Dasgupta, R., & Hirschmann, M. M. 2010, Earth and Planetary Science Letters, 298, 1, doi: 10.1016/j.epsl.2010.06.039

    work page doi:10.1016/j.epsl.2010.06.039 2010

  6. [6]

    2026, Chemical reaction network and rate coefficients for Hycean atmosphere modeling of K2-18b, Zenodo, Zenodo, doi: 10.5281/zenodo.20225015

    Fujisawa, T., Shimada, M., Yoshida, T., & Kuramoto, K. 2026, Chemical reaction network and rate coefficients for Hycean atmosphere modeling of K2-18b, Zenodo, Zenodo, doi: 10.5281/zenodo.20225015

    work page doi:10.5281/zenodo.20225015 2026

  7. [7]

    J., Petigura, E

    Fulton, B. J., Petigura, E. A., Howard, A. W., et al. 2017, AJ, 154, 109, doi: 10.3847/1538-3881/aa80eb

    work page doi:10.3847/1538-3881/aa80eb 2017

  8. [8]

    E., Rothman, L

    Gordon, I. E., Rothman, L. S., Hargreaves, R. J., & et al. 2022, JQSRT, 277, doi: 10.1016/j.jqsrt.2021.107949

    work page doi:10.1016/j.jqsrt.2021.107949 2022

  9. [9]

    2021, ApJL, 921, L8, doi: 10.3847/2041-8213/ac1f92

    Hu, R., Damiano, M., Scheucher, M., & et al. 2021, ApJL, 921, L8, doi: 10.3847/2041-8213/ac1f92

    work page doi:10.3847/2041-8213/ac1f92 2021

  10. [10]

    Innes, H., Tsai, S.-M., & Pierrehumbert, R. T. 2023, ApJ, 953, 168, doi: 10.3847/1538-4357/ace346

    work page doi:10.3847/1538-4357/ace346 2023

  11. [11]

    K., Christoforidis, A., & Kissel, J

    Jessberger, E. K., Christoforidis, A., & Kissel, J. 1988, Nature, 332, 691, doi: 10.1038/332691a0

    work page doi:10.1038/332691a0 1988

  12. [12]

    2024, ApJ, 967, 95, doi: 10.3847/1538-4357/ad3e7e

    Kawamura, T., Yoshida, T., & Terada, N. 2024, ApJ, 967, 95, doi: 10.3847/1538-4357/ad3e7e

    work page doi:10.3847/1538-4357/ad3e7e 2024

  13. [13]

    N., Sagan, C., Arakawa, E

    Khare, B. N., Sagan, C., Arakawa, E. T., et al. 1984, Icarus, 60, 127, doi: 10.1016/0019-1035(84)90142-8

    work page doi:10.1016/0019-1035(84)90142-8 1984

  14. [14]

    S., Fegley, B., Schaefer, L., & Ford, E

    Kite, E. S., Fegley, B., Schaefer, L., & Ford, E. B. 2020, arXiv e-prints. https://arxiv.org/abs/2001.09269

    work page arXiv 2020

  15. [15]

    V., Gordon, I

    Kochanov, R. V., Gordon, I. E., Rothman, L. S., & et al. 2016, JQSRT, 177, 15, doi: 10.1016/j.jqsrt.2016.03.005

    work page doi:10.1016/j.jqsrt.2016.03.005 2016

  16. [16]

    2024, Sci Rep, 14, 2397, doi: 10.1038/s41598-024-52718-9 28

    Koyama, S., Koyama, S., Kamada, A., et al. 2024, Sci Rep, 14, 2397, doi: 10.1038/s41598-024-52718-9 28

    work page doi:10.1038/s41598-024-52718-9 2024

  17. [17]

    D., & Fortney, J

    Lopez, E. D., & Fortney, J. J. 2014, ApJ, 792, 1, doi: 10.1088/0004-637X/792/1/1

    work page doi:10.1088/0004-637x/792/1/1 2014

  18. [18]

    Madhusudhan, N., & Nixon, C. M. 2021, MNRAS, 505, 3414, doi: 10.1093/mnras/stab1500

    work page doi:10.1093/mnras/stab1500 2021

  19. [19]

    Madhusudhan, N., Piette, A. A. A., & Constantinou, S. 2021, ApJ, 918, 1, doi: 10.3847/1538-4357/abfd9c

    work page doi:10.3847/1538-4357/abfd9c 2021

  20. [20]

    2023, ApJL, 956, L13, doi: 10.3847/2041-8213/acf577

    Madhusudhan, N., Sarkar, S., Constantinou, S., & et al. 2023, ApJL, 956, L13, doi: 10.3847/2041-8213/acf577

    work page doi:10.3847/2041-8213/acf577 2023

  21. [21]

    J., Turner, D

    Mlawer, E. J., Turner, D. D., Paine, S. N., & Palchetti, L. 2023, The inclusion of the MT_CKD water vapor continuum model in the HITRAN molecular spectroscopic database, Tech. rep., doi: 10.1016/j.jqsrt.2023.108645

    work page doi:10.1016/j.jqsrt.2023.108645 2023

  22. [22]

    Nakamura, Y., Terada, K., & Tao, C. 2022, J. Geophys. Res. Space Phys., 127, 3, doi: 10.1029/2022JA030312

    work page doi:10.1029/2022ja030312 2022

  23. [23]

    2023, Earth Planets Space, 75, 140, doi: 10.1186/s40623-023-01881-w

    Nakamura, Y., Terada, N., & Koyama, S. 2023, Earth Planets Space, 75, 140, doi: 10.1186/s40623-023-01881-w

    work page doi:10.1186/s40623-023-01881-w 2023

  24. [24]

    A., Brown, L

    Pavlov, A. A., Brown, L. L., & Kasting, J. F. 2001, Journal of Geophysical Research: Planets, 106, 23267, doi: 10.1029/2000JE001448

    work page doi:10.1029/2000je001448 2001

  25. [25]

    2000, Journal of Geophysical Research: Planets, 105, 11981, doi: 10.1029/1999JE001134

    Freedman, R. 2000, Journal of Geophysical Research: Planets, 105, 11981, doi: 10.1029/1999JE001134

    work page doi:10.1029/1999je001134 2000

  26. [26]

    2011, ApJ, 734, L13, doi: 10.1088/2041-8205/734/1/L13

    Pierrehumbert, R., & Gaidos, E. 2011, ApJ, 734, L13, doi: 10.1088/2041-8205/734/1/L13

    work page doi:10.1088/2041-8205/734/1/l13 2011

  27. [27]

    Haywood, R. D. 2018, MNRAS, 480, 5314, doi: 10.1093/mnras/sty2209

    work page doi:10.1093/mnras/sty2209 2018

  28. [28]

    Rogers, L. A. 2015, ApJ, 801, 41, doi: 10.1088/0004-637X/801/1/41

    work page doi:10.1088/0004-637x/801/1/41 2015

  29. [29]

    A., Bodenheimer, P., Lissauer, J

    Rogers, L. A., Bodenheimer, P., Lissauer, J. J., & Seager, S. 2011, ApJ, 738, 59, doi: 10.1088/0004-637X/738/1/59

    work page doi:10.1088/0004-637x/738/1/59 2011

  30. [30]

    S., MacDonald, R

    Schmidt, P. S., MacDonald, R. J., & Tsai, S.-M. 2025, ApJ, 170, 298, doi: 10.3847/1538-3881/ae019a

    work page doi:10.3847/1538-3881/ae019a 2025

  31. [31]

    R., & Grosheintz, L

    Shang-Min, T., Lyons, J. R., & Grosheintz, L. 2017, ApJS, 228, 20, doi: 10.3847/1538-4365/228/2/20

    work page doi:10.3847/1538-4365/228/2/20 2017

  32. [32]

    2011, Earth and Planetary Science Letters, 308, 417, doi: 10.1016/j.epsl.2011.06.011

    Tian, F., Kasting, J., & Zahnle, K. 2011, Earth and Planetary Science Letters, 308, 417, doi: 10.1016/j.epsl.2011.06.011

    work page doi:10.1016/j.epsl.2011.06.011 2011

  33. [33]

    G., Pavlov, A

    Trainer, M. G., Pavlov, A. A., DeWitt, H. L., et al. 2006, Proceedings of the National Academy of Sciences, 103, 18035, doi: 10.1073/pnas.0608561103

    work page doi:10.1073/pnas.0608561103 2006

  34. [34]

    P., Tinetti, G., & et al

    Tsiaras, A., Waldmann, I. P., Tinetti, G., & et al. 2019, Nature Astronomy, 3, 1086, doi: 10.1038/s41550-019-0878-9

    work page doi:10.1038/s41550-019-0878-9 2019

  35. [35]

    F., Batalha, N

    Wogan, N. F., Batalha, N. E., Zahnle, K., & et al. 2024, arXiv e-prints. https://arxiv.org/abs/2401.11082

    work page arXiv 2024

  36. [36]

    2023, Planet

    Yoshida, T., Aoki, S., & Ueno, Y. 2023, Planet. Sci. J., 4, 53, doi: 10.3847/PSJ/acc030

    work page doi:10.3847/psj/acc030 2023

  37. [37]

    2025, ApJ, 985, 5, doi: 10.3847/1538-4357/adc8a5

    Yoshida, T., Arima, K., & Kuroda, T. 2025, ApJ, 985, 5, doi: 10.3847/1538-4357/adc8a5

    work page doi:10.3847/1538-4357/adc8a5 2025

  38. [38]

    2024, Astrobiology, 24, 1074, doi: 10.1089/ast.2024.0048

    Kuramoto, K. 2024, Astrobiology, 24, 1074, doi: 10.1089/ast.2024.0048

    work page doi:10.1089/ast.2024.0048 2024

  39. [39]

    2020, Icarus, 345, 113740, doi: 10.1016/j.icarus.2020.113740

    Yoshida, T., & Kuramoto, K. 2020, Icarus, 345, 113740, doi: 10.1016/j.icarus.2020.113740

    work page doi:10.1016/j.icarus.2020.113740 2020