| Abstract: | The photometric observations and three-dimensional classification in the Vilnius system have been carried out for 13 of the red horizontal branch (RHB) stars in the Galactic thick disk identified by Rose (1985). The photometric spectral types, metallicities [Fe/H], effective temperatures, surface gravities and absolute magnitudes are determined. The age of about 10–12 Gyr is evaluated for this group of stars from comparison with model isochrones, indicating that the age of the thick disk is intermediate between the disk globular and the oldest open clusters. |
