Investigating stellar activity with CoRoT observations

TL;DR

This paper explores stellar magnetic activity using CoRoT asteroseismic data, revealing activity-related frequency and amplitude variations in multiple stars, including the first detection of such activity in HD 49933.

Contribution

It demonstrates the first detection of stellar activity variability through asteroseismology and compares activity signatures across several CoRoT targets, including a planet-hosting star.

Findings

Magnetic activity affects p-mode frequencies and amplitudes.

Frequency shifts correlate with activity levels.

Similar activity signatures are observed in the Sun and other stars.

Abstract

Recently, the study of the CoRoT target HD 49933 showed evidence of variability of its magnetic activity. This was the first time that a stellar activity was detected using asteroseismic data. For the Sun and HD 49933, we observe an increase of the p-mode frequencies and a decrease of the maximum amplitude per radial mode when the activity level is higher. Moreover a similar behavior of the frequency shifts with frequency has been found between the Sun and HD 49933. We study 3 other targets of CoRoT as well, for which modes have been detected and well identified: HD 181420, HD 49385, and HD 52265 (which is hosting a planet). We show how the seismic parameters (frequency shifts and amplitude) vary during the observation of these stars.