Kinematics, ages, and evolutionary status of UV Ceti stars.

The kinematic properties of 93 UV Ceti stars of the solar neighborhood are studied, based on a list of flares within 25 pc of the Sun (π>=0.04"). With updated values for their distances, proper motions and radial velocities, space velocity dispersions are calculated for these stars. It is found that the total velocity dispersion of the flare stars (σ=30+/-3km/s) is similar to that of the F5 V stars from the same catalogue, for which the conventionally estimated mean age is about 3x10^9^yr. Membership of the flare stars to some well-identified kinematic groups and superclusters is studied. A number of flares are identified as members of the Hyades, Sirius or Pleiades groups. The velocity dispersions found for the nearby flare stars and the membership of some of them to young kinematic groups indicate that they belong to the young disk population. The evolutionary status of the UV Ceti stars is discussed on the basis of these results. It is concluded that they do not differ significantly from the flash stars and that, indeed, they may be identified with the older remnants of the flash population of galactic clusters long ago disrupted. A small number (7) of UV Ceti stars have kinematics corresponding to thick disk or halo population. Their long-lived chromospheric activity is interpreted as due to coalescence of old short-period binaries. The question of the age of Proxima Centauri is examined in the context of our results, and found to be compatible with the ages of Alpha Centauri A and B.