Chemical diversity of the atmospheres and interiors of sub-Neptunes: a case study of GJ 436 b
arXiv:2204.05971 · doi:10.1093/mnras/stac1066
Abstract
The atmospheres of sub-Neptunes are expected to exhibit considerable chemical diversity, beyond what is anticipated for gas-giant exoplanets. In the current study, we construct self-consistent radiative transfer and equilibrium chemistry models to explore this chemical diversity. We use GJ 436 b as a case study to further study joint atmosphere-interior models. In particular, we constrain the properties of the interior and atmosphere of the planet based on the available Spitzer measurements. While it is possible to fit the emission spectrum of GJ 436 b using a high-metallicity model, we demonstrate that such an atmosphere is inconsistent with physically plausible interior structures. It remains the case that no existing study can adequately fit the 4.5-micron Spitzer secondary eclipse measurement, which is probably caused by chemical disequilibrium. Finally, an information content analysis reveals that emission and transmission spectra constrain the carbon-to-oxygen ratio and metallicity at different wavelengths, but the former are less susceptible to flat spectra stemming from highly metal-enriched atmospheres. With the recently-launched JWST, we recommend that future analysis of emission and transmission spectra of sub-Neptune planets are carried out self-consistently using both the atmospheric and interior structure models.
23 pages, 15 figures, 2 tables. Accepted for publication in MNRAS
References in corpus (35)
- Mass-Radius Relationships for Solid Exoplanets
- Most 1.6 Earth-Radius Planets are not Rocky
- Growth Model Interpretation of Planet Size Distribution
- Detection of atmospheric haze on an extrasolar planet: The 0.55 - 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope
- Comparing Jupiter interior structure models to Juno gravity measurements and the role of a dilute core
- The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
- Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation
- Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b
- Atmospheric Sulfur Photochemistry on Hot Jupiters
- Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres
- Ranges of Atmospheric Mass and Composition of Super Earth Exoplanets
- New models of Jupiter in the context of Juno and Galileo
- A new equation of state for dense hydrogen-helium mixtures
- Atmospheric Circulation of Eccentric Hot Neptune GJ436b
- AQUA: A Collection of HO Equations of State for Planetary Models
- Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds
- Orbital misalignment of the Neptune-mass exoplanet GJ 436b with the spin of its cool star
- HELIOS-K 2.0 Opacity Calculator and Open-source Opacity Database for Exoplanetary Atmospheres
- The nature and origins of sub-Neptune size planets
- A global analysis of Spitzer and new HARPS data confirms the loneliness and metal-richness of GJ 436 b
- Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets
- Characterization of exoplanets from their formation III: The statistics of planetary luminosities
- Atmosphere Origins for Exoplanet Sub-Neptunes
- IACHEC Cross-Calibration of Chandra, NuSTAR, Swift, Suzaku, and XMM-Newton with 3C 273 and PKS 2155-304
- Superabundance of Exoplanet Sub-Neptunes Explained by Fugacity Crisis
- Evidence of Three Mechanisms Explaining the Radius Anomaly of Hot Jupiters
- A new perspective on interiors of ice-rich planets: Ice-rock mixture instead of ice on top of rock
- Most super-Earths formed by dry pebble accretion are less massive than 5 Earth masses
- Exploring the formation by core accretion and the luminosity evolution of directly imaged planets: The case of HIP 65426 b
- Giant planet formation models with a self-consistent treatment of the heavy elements
- Information content of JWST-NIRSPEC transmission spectra of warm Neptunes
- System-level fractionation of carbon from disk and planetesimal processing
- Supervised Machine Learning for Intercomparison of Model Grids of Brown Dwarfs: Application to GJ 570D and the Epsilon Indi B Binary System
- Ohmic Dissipation in Mini-Neptunes
- On the stellar clustering and architecture of planetary systems