On the frequency dependence of p-mode frequency shifts induced by magnetic activity in Kepler solar-like stars

TL;DR

This study investigates how magnetic activity influences p-mode frequency shifts in various Kepler solar-like stars, revealing potential differences in physical mechanisms compared to the Sun.

Contribution

It extends the analysis of frequency shifts due to magnetic activity to a diverse set of stars with different properties, identifying reliable shifts in five stars.

Findings

Frequency shifts increase with mode order, similar to the Sun.

Different amplitudes of shifts observed across stars.

Possible different physical sources of perturbation in stars beyond the Sun.

Abstract

The variations of the frequencies of the low-degree acoustic oscillations in the Sun induced by magnetic activity show a dependence with radial order. The frequency shifts are observed to increase towards higher-order modes to reach a maximum of about 0.8 muHz over the 11-yr solar cycle. A comparable frequency dependence is also measured in two other main-sequence solar-like stars, the F-star HD49933, and the young 1-Gyr-old solar analog KIC10644253, although with different amplitudes of the shifts of about 2 muHz and 0.5 muHz respectively. Our objective here is to extend this analysis to stars with different masses, metallicities, and evolutionary stages. From an initial set of 87 Kepler solar-like oscillating stars with already known individual p-mode frequencies, we identify five stars showing frequency shifts that can be considered reliable using selection criteria based on Monte Carlo simulations and on the photospheric magnetic activity proxy Sph. The frequency dependence of the frequency shifts of four of these stars could be measured for the l=0 and l=1 modes individually. Given the quality of the data, the results could indicate that a different physical source of perturbation than in the Sun is dominating in this sample of solar-like stars.