HD 49933: A laboratory for magnetic activity cycles

TL;DR

This paper investigates the magnetic activity cycle of HD 49933 through seismic analysis, modeling its internal structure, and examining how near-surface sound-speed changes affect oscillation frequencies, drawing parallels with solar behavior.

Contribution

It combines seismic data with stellar modeling to analyze magnetic cycles and surface effects in HD 49933, advancing understanding of stellar magnetic activity.

Findings

Frequency shifts vary with mode frequency, similar to the Sun.

Seismic models reveal effects of near-surface sound-speed perturbations.

Magnetic cycle influences oscillation mode frequencies.

Abstract

Seismic analyses of the CoRoT target HD 49933 have revealed a magnetic cycle. Further insight reveals that frequency shifts of oscillation modes vary as a function of frequency, following a similar pattern to that found in the Sun. In this preliminary work, we use seismic constraint to compute structure models of HD 49933 with the Asteroseismic Modeling Portal (AMP) and the CESAM code. We use these models to study the effects of sound-speed perturbations in near surface layers on p-mode frequencies.