Influence of stellar X-ray luminosity distribution and its evolution on exoplanetary mass loss

TL;DR

This study examines how the evolving X-ray luminosity of G-type stars influences atmospheric mass loss in close-in exoplanets, revealing that stellar high-energy radiation history critically affects planetary survival and mass distribution.

Contribution

It introduces a scaling law for stellar X-ray luminosity evolution and applies a modified energy-limited escape model to assess exoplanet atmospheric loss.

Findings

High X-ray luminosity stars can evaporate planets within 0.5 AU.

Planet survival depends on the host star's X-ray luminosity history.

Atmospheric escape significantly alters initial planetary mass distribution.

Abstract

Aims: We investigate the influence of high-energy stellar radiation at close-in orbits on atmospheric mass loss during stellar evolution of a G-type star. Methods: High-energy stellar luminosity varies over a wide range for G field stars. The temporal evolution of the distribution of stellar X-ray luminosity and its influence on the evolution of close-in exoplanets is investigated. X-ray luminosity distributions from the Pleiades, the Hyades and the field are used to derive a scaling law for the evolution of the stellar X-ray luminosity distribution. A modified energy-limited escape approach is used to calculate atmospheric mass loss for a broad range of planetary parameters. Results: We show that the evolution of close-in exoplanets strongly depends on the detailed X-ray luminosity history of their host stars, which varies over several orders-of-magnitude for G stars. Stars located at the high-energy tail of the luminosity distribution can evaporate most of its planets within 0.5 AU, while for a moderate luminosity a significant fraction of planets can survive. We show the change on an initial planetary mass distribution caused by atmospheric escape.