Marginal likelihoods of distances and extinctions to stars: computation and compact representation

Abstract

We present a method for obtaining the likelihood function of distance and extinction to a star given its photometry. The other properties of the star (its mass, age, metallicity and so on) are marginalised assuming a simple Galaxy model. We demonstrate that the resulting marginalised likelihood function can be described faithfully and compactly using a Gaussian mixture model. For dust mapping applications we strongly advocate using monochromatic over bandpass extinctions, and provide tables for converting from the former to the latter for different stellar types.

14 pages, 12 figures. Accepted for publication in MNRAS. Source code is available at https://github.com/stuartsale