Inner and Outer Orbits in 13 Resolved Hierarchical Stellar Systems

Abstract

Orbits of inner and outer subsystems in 13 triple or higher-order stellar systems are computed or updated using position measurements and, in three cases, radial velocities. The goal is to determine mutual orbital inclinations, period ratios, and masses to complement the statistics of hierarchical systems. Effect of the subsystems on the motion in the outer orbits (wobble) is explicitly modeled to determine inner mass ratios. Stars studied here (HD 5408, 8036, 9770, 15089, 29310, 286955, 29316, 140538, 144362, 154621, 156034, 185655, and 213235) are bright and nearby (from 15\,pc to 150\,pc). Their inner periods range from 1.7 yr to 49 yr, and the outer periods from 83 to 2400 yr. Some long-period outer orbits are poorly constrained. Four astrometric inner orbits and one outer orbit are computed for the first time.