Short-lived spots in solar-like stars as observed by CoRoT^*

¹ LESIA, CNRS, Université Pierre et Marie Curie, Université Denis Diderot, Observatoire de Paris, 92195 Meudon Cedex, France e-mail: benoit.mosser@obspm.fr
² Institut d'Astrophysique Spatiale, UMR8617, Université Paris XI, Bâtiment 121, 91405 Orsay Cedex, France
³ INAF – Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95123 Catania, Italy

Received: 24 February 2009
Accepted: 5 June 2009

Abstract

Context. CoRoT light curves have an unprecedented photometric quality, having simultaneously a high signal-to-noise ratio, a long time span and a nearly continuous duty-cycle.

Aims. We analyse the light-curves of four bright targets observed in the seismology field and study short-lived small spots in solar-like stars.

Methods. We present a simple spot modeling by iterative analysis. Its ability to extract relevant parameters is ensured by implementing relaxation steps to avoid convergence to local minima of the sum of the residuals between observations and modeling. The use of Monte-Carlo simulations allows us to estimate the performance of the fits.

Results. Our starspot modeling gives a representation of the spots on these stars in agreement with other well tested methods. Within this framework, parameters such as rigid-body rotation and spot lifetimes seem to be precisely determined. Then, the lifetime/rotation period ratios are in the range 0.5-2, and there is clear evidence for differential rotation.