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

Dyad is a Python library for studying the dynamics of binary stars considered as gravitational two-body systems.By convention, astrophysicists designate the brighter of the two components of a binary star as a reference body, which they call the 'primary star', and the dimmer of the two components as a subject body, which they call the 'secondary star'.In a frame centred on the primary star, the secondary star then moves on an elliptical orbit with one focus located at the origin.This orbit can be specified by its orbital elements, namely the semimajor axis (which specifies the size of the ellipse), eccentricity (which specifies the shape of the ellipse), and true anomaly (which specifies the secondary star's location on the ellipse) along with the longitude of its ascending node, its inclination, and its argument of pericentre (which together specify the orientation of the ellipse).