Orbits and Structure of the Quadruple Systems GJ 225.1 and FIN 332

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.