Speckle observations and orbits of multiple stars

TL;DR

This study presents speckle-interferometric observations of multiple star systems, deriving new orbits and resolving previously unobserved components, thereby enhancing understanding of hierarchical stellar configurations.

Contribution

First-time determination of orbits for 27 subsystems and resolution of four bright stars, including new triple systems, using speckle interferometry and combined astrometric and radial velocity data.

Findings

36 orbits computed, 27 for the first time

Four bright stars resolved for the first time

Subsystems in compact hierarchies tend to have less eccentric orbits

Abstract

We report results of speckle-interferometric monitoring of visual hierarchical systems using the newly commissioned instrument NESSI at the 3.5-m WIYN telescope. During one year, 390 measurements of 129 resolved subsystems were made, while some targets were unresolved. Using our astrometry and archival data, we computed 36 orbits (27 for the first time). Spectro-interferometric orbits of seven pairs are determined by combining positional measurements with radial velocities measured, mostly, with the Center for Astrophysics digital speedometers. For the hierarchical systems HIP 65026 (periods 49 and 1.23 years) and HIP 85209 (periods 34 and 1.23 years) we determined both the inner and the outer orbits using astrometry and radial velocities and measured the mutual orbit inclinations of 11.3+-1.0 deg and 12.0+-3.0 deg, respectively. Four bright stars are resolved for the first time; two of those are triple systems. Several visual subsystems announced in the literature are shown to be spurious. We note that subsystems in compact hierarchies with outer separations less than 100 au tend to have less eccentric orbits compared to wider hierarchies.