The Most Metal-Poor Quadruple System of Subdwarfs G89-14

TL;DR

This paper reports the discovery and analysis of G89-14, a highly metal-poor quadruple star system with a hierarchical structure, providing insights into its composition, orbital dynamics, and Galactic halo membership.

Contribution

The study reveals the detailed hierarchical structure and orbital parameters of G89-14, a rare metal-poor quadruple system, using speckle interferometry and mass estimation.

Findings

G89-14 is one of the most metal-poor multiple stars known.

The system has a highly hierarchical orbital structure.

It likely belongs to the Galactic halo.

Abstract

The system of subdwarfs G89-14 is one of the most metal-poor multiple stars with an atmospheric metal abundance $\mathrm{[m/H]}=-1.9$. Speckle interferometry at the 6-m BTA telescope has revealed that G89-14 consists of four components. Measurements of the magnitude difference between the components and published data have allowed their masses to be estimated: $M_{A}\approx0.67 M_{\odot}$, $M_{B}\approx0.24 M_{\odot}$, $M_{C}\approx0.33 M_{\odot}$, and $M_{D}\approx0.22 M_{\odot}$. The ratio of the orbital periods of the subsystems has been obtained, 0.52 yr : 3 000 yr : 650 000 yr (1:5769:1250000), indicative of a high degree of hierarchy of G89-14 and its internal dynamical stability. The calculated Galactic orbital elements and the low metallicity of the quadruple system suggest that it belongs to the Galactic halo.