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 Ariyanto et al. (2005) and Schuster et al. (2006). In an attempt to isolate a sample of metal-weak thick disc stars, we applied the kinematic criteria $V_{\mathrm{rot}}\ge 100$ km s${}^{-1}$, $|U_{LSR}|\le 140$ km s${}^{-1}$, and $|W_{LSR}|\le 100$ km s${}^{-1}$. Fourteen stars satisfying these criteria and having [Fe/H] $\le -1.0$ are included in the sample of 60 stars. Eight of the 14 have [Fe/H] $\ge -1.3$ 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.

18 pages including 13 figures and 7 tables; accepted for publication for MNRAS main journal

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