# V773 Cas, QS Aql, and BR Ind: Eclipsing Binaries as Parts of Multiple Systems

## TL;DR

This study analyzes three eclipsing binary systems within multiple star systems, providing precise physical parameters, orbital elements, and parallax measurements, thereby enhancing understanding of their formation and dynamics.

## Contribution

First detailed analysis combining radial velocities and light curves for V773 Cas, QS Aql, and BR Ind, revealing their complex multiple-star configurations and improved orbital data.

## Key findings

- V773 Cas consists of two G-type stars and a distant A3V component.
- QS Aql's inner pair is B6V and F1V stars with a highly eccentric outer orbit.
- BR Ind is a quadruple system with two eclipsing K dwarfs and a distant binary.

## Abstract

Eclipsing binaries remain crucial objects for our understanding of the universe. In particular, those that are components of multiple systems can help us solve the problem of the formation of these systems. Analysis of the radial velocities together with the light curve produced for the first time precise physical parameters of the components of the multiple systems V773 Cas, QS Aql, and BR Ind. Their visual orbits were also analyzed, which resulted in slightly improved orbital elements. What is typical for all these systems is that their most dominant source is the third distant component. The system V773 Cas consists of two similar G1-2V stars revolving in a circular orbit and a more distant component of the A3V type. Additionally, the improved value of parallax was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following: the inner eclipsing pair is composed of B6V and F1V stars, and the third component is of about the B6 spectral type. The outer orbit has high eccentricity of about 0.95, and observations near its upcoming periastron passage between the years 2038 and 2040 are of high importance. Also, the parallax of the system was derived to be about 2.89 mas, moving the star much closer to the Sun than originally assumed. The system BR Ind was found to be a quadruple star consisting of two eclipsing K dwarfs orbiting each other with a period of 1.786 days; the distant component is a single-lined spectroscopic binary with an orbital period of about 6 days. Both pairs are moving around each other on their 148 year orbit.