Surface Brightness--Color Relation for Eclipsing Binaries with ubvy Photometry

Abstract

The relation between visual surface brightness and (b-y)_0 color index is constructed for eclipsing binaries with Hipparcos parallaxes and photometry in the Stromgren four-color ubvy system. The relation is consistent with the Popper relation derived for stars with angular diameters obtained mainly from interferometry or from the lunar occultation method. It is shown that the Lutz-Kelker correction to magnitudes is in this case negligible.