Orbits of subsystems in four hierarchical multiple stars

TL;DR

This paper presents spectroscopic orbits and detailed configurations of seven nearby multiple star systems, revealing their hierarchical structures, orbital parameters, and some peculiar subsystem characteristics.

Contribution

It provides new orbital solutions and system architectures for seven multiple star systems, including updated visual orbits and analysis of subsystem peculiarities.

Findings

Determined orbital parameters for seven multiple star systems.

Revealed peculiar mass ratio and magnitude difference in HIP 28790 subsystem.

Updated visual orbit of HIP 9642 remains poorly constrained.

Abstract

Seven spectroscopic orbits in nearby solar-type multiple stars are presented. The primary of the chromospherically active star HIP 9642 is a 4.8-day double-lined pair; the outer 420-yr visual orbit is updated, but remains poorly constrained. HIP 12780 is a quadruple system consisting of the resolved 6.7-yr pair FIN 379 Aa,Ab, for which the combined orbit, masses, and orbital parallax are determined here, and the single-lined binary Ba,Bb with a period of 27.8 days. HIP 28790 is a young quintuple system composed of two close binaries Aa,Ab and Ba,Bb with periods of 221 and 13 days, respectively, and a single distant component C. Its subsystem Ba,Bb is peculiar, having the spectroscopic mass ratio of 0.89 but a magnitude difference of ~2.2 mag. HIP 64478 also contains five stars: the A-component is a 29-year visual pair with a previously known 4-day twin subsystem, while the B-component is a contact binary with a period of 5.8 hours, seen nearly pole-on.