The Evolution of Stellar Rotation and the hydrogen atmospheres of habitable-zone Terrestrial Planets

TL;DR

This paper presents a method to model how stellar rotation influences the evaporation of hydrogen atmospheres on habitable-zone terrestrial planets, emphasizing the importance of stellar activity evolution in planetary atmosphere retention.

Contribution

It introduces an accessible approach combining atmospheric models to assess the impact of stellar initial rotation rates on planetary atmosphere evolution.

Findings

Initial stellar rotation rate critically affects hydrogen envelope retention.

Stellar activity evolution must be carefully modeled in planetary atmosphere studies.

The method enables easier predictions of atmospheric loss based on stellar properties.

Abstract

Terrestrial planets formed within gaseous protoplanetary disks can accumulate significant hydrogen envelopes. The evolution of such an atmosphere due to XUV driven evaporation depends on the activity evolution of the host star, which itself depends sensitively on its rotational evolution, and therefore on its initial rotation rate. In this letter, we derive an easily applicable method for calculating planetary atmosphere evaporation that combines models for a hydrostatic lower atmosphere and a hydrodynamic upper atmosphere. We show that the initial rotation rate of the central star is of critical importance for the evolution of planetary atmospheres and can determine if a planet keeps or loses its primordial hydrogen envelope. Our results highlight the need for a detailed treatment of stellar activity evolution when studying the evolution of planetary atmospheres.