Chromospheric changes in K stars with activity

TL;DR

This study models the chromospheric structure of K stars with varying activity levels, revealing a strong correlation between radiative losses and activity indicators, extending previous G star research.

Contribution

It provides detailed chromospheric models for K stars at different activity levels, expanding understanding of stellar activity effects beyond G stars.

Findings

Strong correlation between radiative losses and activity index .

Chromospheric models match observed spectral profiles.

Activity influences chromospheric heating mechanisms.

Abstract

We study the differences in chromospheric structure induced in K stars by stellar activity, to expand our previous work for G stars, including the Sun as a star. We selected six stars of spectral type K with 0.82$<B-V<$0.90, including the widely studied Epsilon Eridani and a variety of magnetic activity levels. We computed chromospheric models for the stars in the sample, in most cases in two different moments of activity. The models were constructed to obtain the best possible match with the Ca II K and the H$\beta$ observed profiles. We also computed in detail the net radiative losses for each model to constrain the heating mechanism that can maintain the structure in the atmosphere. We find a strong correlation between these losses and \Sc, the index generally used as a proxy for activity, as we found for G stars.