1999PASP..111.1515V

Reliable prediction of stellar diameters, particularly angular diameters, is a useful and necessary tool for the increasing number of milliarcsecond resolution studies being carried out in the astronomical community. A new and accurate technique of predicting angular sizes is presented for main-sequence stars, giant and supergiant stars, and more evolved sources such as carbon stars and Mira variables. This technique uses observed K and either V or B broadband photometry to predict V=0 or B=0 zero-magnitude angular sizes, which are then readily scaled to the apparent angular sizes with the V or B photometry. The spread in the relationship is 2.2% for main-sequence stars, 11%-12% for giant and supergiant stars, and 20%-26% for evolved sources. Compared to other simple predictions of angular size, such as linear radius-distance methods or blackbody estimates, zero-magnitude angular size predictions can provide apparent angular sizes with errors that are 2-5 times smaller.