Searching for the metal-weak thick disc in the solar neighbourhood

Abstract

An abundance analysis is presented of 60 metal-poor stars drawn from catalogues of nearby stars provided by Arifyanto et al. and Schuster et al. In an attempt to isolate a sample of metal-weak thick disc stars, we applied the kinematic criteria V/subrot >= 100kms/sup -1,|U/sub LSR| <= 140kms/sup-1 (LSR - local standard of rest) and |W/sub LSR| <= 100kms/sup -1. 14 stars satisfying these criteria and having [Fe/H] <= -1.0 are included in the sample of 60 stars. Eight of the 14 have [Fe/H] >= -1.3 and may be simply thick disc stars of slightly lower than average [Fe/H]. The other six have [Fe/H] from -1.3 to -2.3 and are either metal-weak thick disc stars or halo stars with kinematics mimicking those of the thick disc. The sample of 60 stars is completed by eight thick disc stars, 20 stars of a hybrid nature (halo or thick disc stars) and 18 stars with kinematics distinctive of the halo.