Beyond gas dwarfs and water worlds: hybrid envelopes among the M-dwarf sub-Neptunes characterised with JWST

arXiv:2609.34635 · astro-ph.EP · Submitted 2026-09-28 · Read on arXiv

astro-ph.EP

Submitted: 2026-09-28

Updated: 2026-10-05

Terminology

• Metallicity — 30× in this paper · explained in 3 episodes
• Core — 16× in this paper · explained in 2 episodes
• Abundance — 7× in this paper · explained in 1 episode
• Degeneracy — 7× in this paper · explained in 3 episodes
• Consistency — 3× in this paper · explained in 3 episodes
• Calibration — 2× in this paper · explained in 7 episodes
• Ab Initio — 1× in this paper · explained in 1 episode
• Active Regions — 1× in this paper · explained in 1 episode
• Fidelity — 1× in this paper · explained in 2 episodes
• Provenance — 1× in this paper · explained in 3 episodes
• Robustness — 1× in this paper · explained in 5 episodes
• Transmission spectroscopy — 1× in this paper · explained in 2 episodes
• World Model — 1× in this paper · explained in 7 episodes

Sources

• JWST Reveals CH$_4$, CO$_2$, and H$_2$O in a Metal-rich Miscible Atmosphere on a Two-Earth-Radius Exoplanet
• The Gradient of Mean Molecular Weight Across the Radius Valley
• Transmission Spectrum of the Benchmark Temperate Exo-Neptune TOI-1231 b
• A water-rich interior in the temperate sub-Neptune K2-18 b revealed by JWST
• NIRPS tightens the mass estimate of GJ 3090 b and detects a planet near the stellar rotation period
• A window for water-hydrogen demixing on warm metal-rich sub-Neptunes

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