Orbits of Six Triple Systems

TL;DR

This study analyzes the orbits of six triple star systems using combined position and velocity data to understand their structure and formation, revealing diverse orbital configurations and potential resonances.

Contribution

It provides new orbital parameters and insights into the dynamical stability and resonance conditions of six triple stellar systems.

Findings

Inner periods range from 0.5 days to 44 years.

HIP 64836 may be in a 1:6 mean motion resonance.

HIP 105404 has the shortest outer period of 3.34 years.

Abstract

Joint analysis of position measurements and radial velocities of six triple stellar systems is conducted to determine their inner and/or outer orbits. Accumulation of such data is needed to study the architecture of stellar hierarchies and its relation to the formation mechanisms. The inner periods in the six systems (HIP 11783, 64836, 72423, 84720, 89234, and 105404) range from 0.5 days to 44 yr. The shortest outer period of 3.34 yr is found in the compact triple HIP~105404 (BS Ind). The resolved triple system HIP 64836 has comparable inner and outer periods (5 and 30 yr), placing it near the limit of dynamical stability, while its quasi-circular and coplanar orbits suggest a 1:6 mean motion resonance. The periods in HIP 89234 (44 and ~450 yr) are also comparable, but the mutual orbit inclination is large, 54 degrees. Masses of the components are estimated and each system is discussed individually.