H$_\alpha$-activity and ages for stars in the SARG survey

TL;DR

This study investigates the use of H$_\alpha$ line variations as an indicator of stellar activity and age in solar-type stars, revealing correlations with radial velocity variations and confirming its utility for stars younger than 1.5 Gyr.

Contribution

The paper demonstrates that H$_\alpha$ activity index effectively indicates stellar activity, rotation periods, and ages, and helps distinguish activity-induced RV signals in binary star systems.

Findings

H$_\alpha$ index correlates with stellar activity and RV variations.

H$_\alpha$ can serve as an age indicator for stars younger than 1.5 Gyr.

Stellar activity can mimic planetary signals in RV measurements.

Abstract

Stellar activity influences radial velocity (RV) measurements and can also mimic the presence of orbiting planets. As part of the search for planets around the components of wide binaries performed with the SARG High Resolution Spectrograph at the TNG, it was discovered that HD 200466A shows strong variation in RV that is well correlated with the activity index based on H$_\alpha$. We used SARG to study the H$_\alpha$ line variations in each component of the binaries and a few bright stars to test the capability of the H$_\alpha$ index of revealing the rotation period or activity cycle. We also analysed the relations between the average activity level and other physical properties of the stars. We finally tried to reveal signals in the RVs that are due to the activity. At least in some cases the variation in the observed RVs is due to the stellar activity. We confirm that H$_\alpha$ can be used as an activity indicator for solar-type stars and as an age indicator for stars younger than 1.5 Gyr.