Orbits and structure of quadruple systems GJ 225.1 and FIN 332

TL;DR

This study analyzes the orbital architecture of two rare quadruple star systems, deriving their orbital parameters and discussing their formation and dynamics, with implications for understanding multiple star system evolution.

Contribution

It provides updated orbital elements and insights into the mutual orientations and eccentricities of two quadruple systems, expanding knowledge of their structure and formation.

Findings

GJ 225.1 has nearly coplanar inner orbits with a ~2 kyr outer orbit.

FIN 332's inner orbits are highly eccentric with similar orientations.

Outer orbit of FIN 332 is inclined relative to inner orbits.

Abstract

Only a handful of quadruple systems with two accurate inner visual orbits are known. Architecture of two such systems is studied here to determine period ratios, mutual orbit orientation, and other parameters; updated orbital elements and their errors are derived. Gliese 225.1 (HIP 28442) is composed of three K-type and one M-type dwarfs and has inner orbital periods of 67.2+-0.2 and 23.4+-0.5 yr. Its inner orbits have small mutual inclination and are likely coplanar with the outer orbit of ~2 kyr period. The quadruple system FIN 332 (HIP 92037) consists of four early A type stars with similar masses and magnitudes. Both its inner orbits with periods of 27.6+-0.2 and 39.8+-0.4 yr have large eccentricities (0.82 and 0.84). Their orientation in the sky is remarkably similar. In contrast, the outer orbit with a period of ~5 kyr has a large relative inclination to the inner orbits. Dynamics and formation of these quadruple systems are briefly discussed.