The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star

TL;DR

This study models the evolution of X-ray and EUV radiation in solar-like stars based on rotational evolution, revealing how initial rotation rates influence stellar high-energy emissions and their impact on planetary atmospheres.

Contribution

It presents a new rotational evolution model linking initial star rotation rates to X-ray/EUV emission tracks, validated against star cluster observations.

Findings

Stars with different initial rotations stay at saturation for 10-300 Myr.

X-ray luminosity distribution varies widely between 20-500 Myr.

Rotational evolution causes diverse planetary atmospheric evolution paths.

Abstract

Aims. We aim to describe the pre-main sequence and main-sequence evolution of X-ray and extreme-ultaviolet radiation of a solar mass star based on its rotational evolution starting with a realistic range of initial rotation rates. Methods. We derive evolutionary tracks of X-ray radiation based on a rotational evolution model for solar mass stars and the rotation-activity relation. We compare these tracks to X-ray luminosity distributions of stars in clusters with different ages. Results. We find agreement between the evolutionary tracks derived from rotation and the X-ray luminosity distributions from observations. Depending on the initial rotation rate, a star might remain at the X-ray saturation level for very different time periods, approximately from 10 Myr to 300 Myr for slow and fast rotators, respectively. Conclusions. Rotational evolution with a spread of initial conditions leads to a particularly wide distribution of possible X-ray luminosities in the age range of 20 to 500 Myrs, before rotational convergence and therefore X-ray luminosity convergence sets in. This age range is crucial for the evolution of young planetary atmospheres and may thus lead to very different planetary evolution histories.