Upcoming support for triple stellar systems in PHOEBE

Abstract

Eclipsing binary stars allow for the direct measurement of stellar parameters and distances and are therefore an important tool in the calibration of stellar relationships. In benchmark cases, we can achieve a precision of 2-3% in fundamental stellar parameters. Due to tighter constraints caused by mutual eclipse events, systems with additional companions allow achieving precision as low as 0.5%. Triple systems have also been proposed as a mechanism for explaining an overabundance of short-period tight binaries. Despite all of this, we do not yet have a complete model for these multiple star systems that include tight binaries. In order to precisely and accurately model these complex systems, we must take into account several considerations, including: light time effects, perturbations to orbital elements, and the distortion of the stellar surfaces. Including all of these into a comprehensive treatment of triple and higher order systems within PHOEBE is currently under development and planned for an upcoming release.