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.
@article{arxiv.1008.4399,
title = {CoRoT reveals a magnetic activity cycle in a Sun-like star},
author = {Rafael A. Garcia and Savita Mathur and David Salabert and Jerome Ballot and Clara Regulo and Travis S. Metcalfe and Annie Baglin},
journal= {arXiv preprint arXiv:1008.4399},
year = {2010}
}
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