[astro-ph.EP] The atmospheres of sub-Neptunes provide a window into their internal structure and history, shedding light on the origin of this common, but enigmatic, class of exoplanets.
![Mass-radius diagram of known exoplanets together with model curves taken from A. Aguichine et al. (2021) and L. Zeng et al. (2019). Exoplanet data shown with colored dots were taken from the NASA Exoplanet Archive (J. L. Christiansen et al. 2025) on April 2, 2026. The transiting exoplanets in the HD 191939 system are highlighted with larger markers, error bars and a red outline.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-SPACE.png?resize=1200%2C714&ssl=1)
[astro-ph.EP] The atmospheres of sub-Neptunes provide a window into their internal structure and history, shedding light on the origin of this common, but enigmatic, class of exoplanets.