Europlanet Science Congress 2020
Virtual meeting
21 September – 9 October 2020
Europlanet Science Congress 2020
Virtual meeting
21 September – 9 October 2020
EPSC Abstracts
Vol. 14, EPSC2020-624, 2020, updated on 13 May 2024
https://doi.org/10.5194/epsc2020-624
Europlanet Science Congress 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Are sub-Neptunes irradiated ocean planets?

Olivier Mousis1, Magali Deleuil1, Artyom Aguichine1, Emmanuel Marcq2, and Lorena Acuna Aguirre1
Olivier Mousis et al.
  • 1Laboratoire d'Astrophysique de Marseille, Marseille, France (olivier.mousis@lam.fr)
  • 2LATMOS/CNRS/Sorbonne Universit\'e/UVSQ, 11 boulevard d'Alembert, Guyancourt, F-78280, France

Small planets (1-3.9 Rearth) constitute more than half of the inventory of the 4000-plus exoplanets discovered so far. Smaller planets are sufficiently dense to be rocky, but those with radii larger than 1.6 Rearth are thought to display in many cases hydrogen/helium gaseous envelopes up to 30% of the planetary mass. These low-mass planets are highly irradiated and the question of their origin, evolution, and possible links remains open. Here we show that close-in ocean planets affected by greenhouse effect display hydrospheres in supercritical state, which generate inflated atmospheres without invoking the presence of large hydrogen/helium gaseous envelopes. We present a new set of mass-radius relationships for ocean planets with different compositions and different equilibrium temperatures, which are found to be well adapted to low-density sub-Neptune planets. Our model suggests that super-Earths and water-rich sub-Neptunes could belong to the same family of planets, i.e. hydrogen/helium-free planets, with differences between their interiors simply resulting from the variation in the water content. 

How to cite: Mousis, O., Deleuil, M., Aguichine, A., Marcq, E., and Acuna Aguirre, L.: Are sub-Neptunes irradiated ocean planets?, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-624, https://doi.org/10.5194/epsc2020-624, 2020.