Spectroscopy of high proper motion stars in the ground--based UV

TL;DR

This study provides detailed spectroscopic analysis of 14 metal-poor high proper motion stars, revealing their diverse galactic origins and chemical compositions, including heavy metal and r-process element abundances, using high-resolution ground-based UV spectra.

Contribution

First detailed spectroscopic analysis of high proper motion stars in the UV range, linking their chemical properties to galactic population membership.

Findings

Stars belong to different galactic components: thin disk, thick disk, and halo.

Chemical compositions vary, with some stars showing heavy metal overabundance and r-process enhancement.

One star's chemical and kinematic properties suggest accreted halo origin.

Abstract

Based on high quality spectral data (spectral resolution R>60000) within the wavelength range of 3550-5000 AA we determined main parameters (effective temperature, surface gravity, microturbulent velocity, and chemical element abundances including heavy metals from Sr to Dy) for 14 metal-deficient G-K stars with large proper motions. The stars we studied have a wide range of metallicity: [Fe/H]=-0.3 \div -2.9. Abundances of Mg, Al, Sr and Ba were calculated with non-LTE line-formation effects accounted for. Abundances both of the radioactive element Th and r-process element Eu were determined using synthetic spectrum calculations. We selected stars that belong to different galactic populations according to the kinematical criterion and parameters determined by us. We found that the studied stars with large proper motions refer to different components of the Galaxy: thin, thick disks and halo. The chemical composition of the star BD+80 245 located far from the galactic plane agrees with its belonging to the accreted halo. For the giant HD115444 we obtained [Fe/H]=-2.91, underabundance of Mn, overabundance of heavy metals from Ba to Dy, and, especially high excess of the r-process element Europium: [Eu/Fe]=+1.26. Contrary to its chemical composition typical for halo stars, HD115444 belongs to the disc population according to its kinematic parameters.