Absolute magnitude and kinematics of oxygen Mira variables

Abstract

A new maximum likelihood method, using apparent magnitudes, proper motions and radial velocities, has been applied to a sample of 90 Mira stars extracted from the HIPPARCOS Input Catalogue (INCA) to determine absolute magnitudes and kinematics. Using this new method three different groups of Mira stars have been identified in the sample, with different luminosities, kinematics and scale height. Two of them are well determined and are identified respectively with the old disk population and the extended thick disk-halo population. The third one is too small and peculiar and its identification has to be left for further studies. Using these results the stars of the sample are classified into the groups and their distances are estimated. These distances are compared with independent determinations obtained from K-band and near-infrared narrow band photometry.