CoRoT reveals a magnetic activity cycle in a Sun-like star

TL;DR

This paper reports the detection of a magnetic activity cycle in the star HD49933 using CoRoT photometric data, showing solar-like oscillations and frequency modulations indicative of stellar magnetic activity.

Contribution

It presents the first evidence of a stellar magnetic activity cycle in a Sun-like star outside the Sun, based on asteroseismic data from CoRoT.

Findings

Detected a modulation of at least 120 days in oscillation frequencies.

Observed a correlation between frequency shifts and mode amplitudes.

Provided constraints for stellar dynamo models under different conditions.

Abstract

The 11-year activity cycle of the Sun is a consequence of a dynamo process occurring beneath its surface. We analyzed photometric data obtained by the CoRoT space mission, showing solar-like oscillations in the star HD49933, for signatures of stellar magnetic activity. Asteroseismic measurements of global changes in the oscillation frequencies and mode amplitudes reveal a modulation of at least 120 days, with the minimum frequency shift corresponding to maximum amplitude as in the Sun. These observations are evidence of a stellar magnetic activity cycle taking place beneath the surface of HD49933 and provide constraints for stellar dynamo models under conditions different from those of the Sun.