Speckle Interferometry of Metal-Poor Stars in the Solar Neighborhood.II

TL;DR

This study used speckle interferometry with a 6-m telescope to observe 115 metal-poor stars near the Sun, discovering close companions and resolving multiple star systems, thereby enhancing understanding of stellar multiplicity in the halo and thick disk.

Contribution

First-time resolution of close companions in metal-poor stars using speckle interferometry, providing new data on stellar multiplicity ratios in the halo and thick disk.

Findings

12 stars have close companions within 1 arcsecond

8 systems are newly resolved astrometrically

Star system ratio of 147:64:9:1 for single, binary, triple, quadruple systems

Abstract

The results of speckle interferometric observations of 115 metal-poor stars [m/H]<-1 within 250 pc from the Sun and with proper motions mu <= 0.2"/yr, made with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, are reported. Close companions with separations ranging from 0.034" to 1" were observed for 12 objects - G76-21, G59-1, G63-46, G135-16, G168-42, G141-47, G142-44, G190-10, G28-43, G217-8, G130-7, and G89-14 - eight of them are astrometrically resolved for the first time. The newly resolved systems include one triple star - G190-10. If combined with spectroscopic and visual data, our results imply a single:binary:triple:quadruple star ratio of 147:64:9:1 for a sample of 221 primary components of halo and thick-disk stars.