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 rot ≥ 100 km s −1 , |ULSR |≤ 140 km s −1 (LSR – local standard of rest) and |W LSR |≤ 100 km s −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.