Contact Binary Stars as Standard Candles

Abstract. The orbital period is a measure of the size of a contact binary star, and can be combined with color to predict its luminosity to a fraction of stellar magnitude. This novel application of contact binary systems currently has limitations that we describe in the text but is potentially capable of providing a reasonable means of estimating distances to stellar systems at the level comparable to that achievable for Cepheids or other pulsating stars. 1