A planetary eclipse map of CoRoT-2a

Comprehensive lightcurve modeling combining rotational-modulation and transits

Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: khuber@hs.uni-hamburg.de

Received: 10 July 2009
Accepted: 12 September 2009

Abstract

We analyze the surface structure of the planet host star CoRoT-2a using a consistent model for both the “global” (i.e., rotationally modulated) lightcurve and the transit lightcurves, using data provided by the CoRoT mission. After selecting a time interval covering two stellar rotations and six transits of the planetary companion CoRoT-2b, we have adopted a “strip” model of the surface to reproduce the photometric modulation inside and outside the transits simultaneously. Our reconstructions show that it is possible to achieve appropriate fits for the entire subinterval using a low-resolution surface model with 36 strips. The surface reconstructions indicate that the brightness on the eclipsed section of the stellar surface is (6±1)% lower than the average brightness of the remaining surface. This result suggests a concentration of stellar activity in a band around the stellar equator similar to the behavior observed on the Sun.