CARMENES input cat. of M dwarfs VIII

We identify 191 young M dwarf candidates (~12%), 113 of which are newly recognised in this work. In this young sample, there are 118 very active stars based on H{alpha} emission, fast rotation, and X-ray and ultraviolet emission excesses. Of them, 27 have also strong magnetic fields, nine of which are likely younger than 50Ma.

Additionally, there are 87 potentially young stars and 99 stars with a dubious youth classification, which may increase the fraction of young stars to an astounding 24%. Only one star out of the 2187 exhibits kinematics typical of the old Galactic halo. A combined analysis of kinematic and rotation-activity properties provides a robust method to identify young M dwarfs from archival data.

However, more observational effort is needed to ascertain the true nature of numerous young star candidates in the field and, perhaps more importantly, precisely quantify their age.