Dyad: a binary-star dynamics and statistics library for Python

Abstract

Dyad is a Python library for studying the dynamics of binary stars considered as gravitational two-body systems. The dynamics of a binary star are determined by its primary and secondary stars' masses along with the secondary star's six orbital elements as defined in a frame comoving with the primary star. In a population of binary stars these eight parameters vary from member to member and can each be treated as a random variable having some probability distribution. Dyad provides a class, dyad.TwoBody, and a module, dyad.stats, for dealing with such a population of binary stars. The dyad.TwoBody class represents a gravitational two-body system while the dyad.stats module provides a suite of classes representing the probability distributions of (1) stellar masses (including those proposed by Kroupa, 2001, and Salpeter, 1955) as well as (2) mass ratios and orbital elements (including those proposed by Duquennoy & Mayor, 1991, and Moe & Di Stefano, 2017). The software repository is at https://github.com/AmeryGration/dyad .