Talk

Do exoplanet hunters dream of stellar activity?

Alejandro Suárez Mascareño, Instituto de Astrofísica de Canarias

Since the arrival of high precision radial velocity measurements (RV), stellar activity became one of the main causes of concern of the exoplanet community Intrinsic variations of the magnetic regions on the stellar surface induce RV variations both at the timescales of the stellar rotation and the magnetic cycle of the stars. This was considered to be an unbeatable obstacle for some time. A dreaded ideat that brought sadness to the hearts of exoplanet hunters. Fearing they would never be able to detect the small signals caused by Earth-mass planets, they resorted to extreme selection criterias that excluded most stars as potential candidates. Looking at the quietest among the quietest stars they realized it was not enough, for no matter how quiet a star is, it would always be noisier than an Earth-mass planet. That could have been the end, but the answer lied right in front of their eyes. For it was not to turn their eyes away from stellar activity, but to embrace it and understand it. And so many astronomers began a journey into the realm of stellar studies only to discover a fascinating new world that actually had always been around the corner. We present the results of a study conducted over hundreds of stars in the solar vicinity, with spectral types ranging from F0 to M6, combining measurements from different ground sources (from HARPS and HARPS-N, to the Mount Wilson HK project), aimed at the detection, characterization of such signals and their statistical properties. These results should allow for a better understanding of the behaviour of late type stars, the influence of stellar activity in their RV measurements and their dynamo mechanism.