Binary orbits from combined astrometric and spectroscopic data

Astrophysics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK
e-mail: l.lucy@imperial.ac.uk

Received: 20 October 2017
Accepted: 1 January 2018

Abstract

An efficient Bayesian technique for estimation problems in fundamental stellar astronomy is tested on simulated data for a binary observed both astrometrically and spectroscopically. Posterior distributions are computed for the components’ masses and for the binary’s parallax. One thousand independent repetitions of the simulation demonstrate that the 1- and 2-σ credibility intervals for these fundamental quantities have close to the correct coverage fractions. In addition, the simulations allow the investigation of the statistical properties of a Bayesian goodness-of-fit criterion and of the corresponding p-value. The criterion has closely similar properties to the traditional χ² test for minimum-χ² solutions.