CoRoT-2a magnetic activity: hints for possible star-planet interaction

TL;DR

This study investigates the magnetic activity of the young star CoRoT-2a with a hot Jupiter, revealing potential star-planet magnetic interactions through spot activity patterns and flux variance modulation.

Contribution

The paper presents evidence of star-planet magnetic interaction in CoRoT-2a by analyzing spot activity and flux variations, using techniques adapted from solar studies.

Findings

Active regions are located in two longitudes separated by 180 degrees.

Total spotted area oscillates with an 8.9-day period, near 10 times the planet's synodic period.

Stellar flux variance is modulated in phase with the planet's orbit.

Abstract

CoRoT-2a is a young (about 0.5 Gyr) G7V star accompanied by a transiting hot-Jupiter, discovered by the CoRoT satellite (Alonso et al. 2008; Bouchy et al. 2008). An analysis of its photospheric activity, based on spot modelling techniques previously developed by our group for the analysis of the Sun as a star, shows that the active regions on CoRoT-2a arised within two active longitudes separated by about 180 degrees and rotating with periods of 4.5221 and 4.5543 days, respectively, at epoch of CoRoT observations (112 continous days centered at 2007.6). We show that the total spotted area oscillates with a period of about about 8.9 days, a value close to 10 times the synodic period of the planet with respect to the active longitude pattern rotating in 4.5221 days. Moreover, the variance of the stellar flux is modulated in phase with the planet orbital period. This suggests a possible star-planet magnetic interaction, a phenomenon already seen in other extrasolar planetary systems hosting hot-Jupiters.