Physics Of Eclipsing Binaries. VIII. Multiple systems

TL;DR

This paper introduces a new dynamical model in Phoebe for accurately simulating the complex interactions in multiple stellar systems, including perturbations, relativistic effects, and light-time effects, enhancing the precision of eclipse timing analysis.

Contribution

It presents a novel n-body dynamical model in Phoebe that incorporates advanced physical effects for the study of multiple stellar systems, which was not previously available.

Findings

The model accounts for mutual perturbations, oblateness, relativistic, and light-time effects.

It allows for hierarchical or two-pairs initial configurations.

Enables more precise modeling of eclipse timings and durations.

Abstract

Multiple stellar systems are common especially among O and B stars. In order to accurately describe their dynamics, interactions among components must be accounted for. In this work, we describe the new dynamical model in Phoebe, which could be used just for this purpose. The n-body model is based on the Reboundx numerical integrator and accounts for mutual perturbations, oblateness, relativistic effects, or light-time effects. The initial conditions can be set up as hierarchical or two-pairs geometry. For comparison purposes, we also provide a simplified keplerian model. Photometric computations work similarly as before, with Roche distortions for pairs of components (or for centres of mass, if hierarchical), and all mutual eclipses. If the time span of observations is long enough, so that perturbations (precession, resonances) are manifested in eclipse timings or durations, this allows to construct order-of-magnitude more precise models of stellar systems. This draft refers to a development version of Phoebe, available at https://github.com/miroslavbroz/phoebe2/tree/interferometry . It is not yet included in the official Phoebe repository!