The dependence of He I 10830 absorption on X-ray luminosity in RS CVn binaries and very active F and G main-sequence stars

Abstract

A study of the relationship between soft X-ray luminosity and He I 10830 equivalent width in RS CVn binaries and very active late-type main-sequence stars is made. Long-period RS CVns and very active F and G main-sequence stars show strong dependence on their X-ray luminosities. This is attributed to the dominance of coronal excitation of the line in these stars. Short-period RS CVn binaries have lower He I 10830 absorption compared to their X-ray emission. This phenomenon is explained by the presence of He I emission region also in their chromospheres.