Sub-Jovian desert of exoplanets at its boundaries

Parameter dependence along the main sequence

¹ ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Szombathely, Szent Imre h. u. 112, 9700, Hungary
e-mail: xilard1@gothard.hu
² MTA-ELTE Exoplanet Research Group, Szombathely, Szent Imre h. u. 112, 9700, Hungary
³ MTA-ELTE Lendület “Momentum” Milky Way Research Group, Szombathely, Szent Imre h. u. 112, 9700, Hungary
⁴ Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, ELKH, Budapest, Konkoly-Thege Miklós út 15–17, 1121, Hungary
⁵ ELTE Eötvös Loránd University, Doctoral School of Physics, Budapest, Pázmány Péter sétány 1/A, 1117, Hungary
⁶ Graduate School of Physics, University of Szeged, Szeged, Dóm tér 9, 6720, Hungary
⁷ CSFK, MTA Centre of Excellence, Budapest, Konkoly Thege Miklós út 15–17, 1121, Hungary
⁸ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁹ Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1171 Budapest, Hungary
¹⁰ MTA CSFK Lendület Near-Field Cosmology Research Group, Budapest, Konkoly-Thege Miklós u. 15–17., 1121, Hungary

Received: 30 August 2022
Accepted: 19 December 2022

Abstract

Context. The lack of sub-Jovian planets on orbits of P_orb < 3 days is a puzzling aspect of galaxy formation with regard to the distribu-tion of exoplanets whose origins are currently unresolved.

Aims. The possible explanations behind the formation of the sub-Jovian or Neptunian desert include several scenarios that can lead to different shapes for the boundary, predicting various dependencies between the position of the boundary and the stellar parameters.

Methods. We explored the exoplanet distribution in various 2D and 3D projections, revealing the stellar-dependent substructures in the P_orb–M_P and the P_orb–R_P parameter plane.

Results. We demonstrate that the upper boundary includes a range of planets, namely, inflated hot Jupiters and normal hot Jupiters, in the two parameter planes, respectively. We confirm the dependence of the boundary on several stellar parameters and, based on a fuzzy clustering analysis, we provide quantitative formulae for the dependencies in groups of smaller and larger planets. The overall period-radius distribution shows chemical substructures as well, with the boundary being dependent on volatiles and alpha-elements, alongside marginal (to none) dependence found for refractory elements.

Conclusions. These findings confirm multiple plausible causes for the formation of the desert, particularly preferring those scenarios related to the irradiation-driven loss of the atmospheres of moderately massive planets as the predominant process in shaping planetary distributions.