On the use of empirical bolometric corrections for stars

Abstract

When making use of tabulations of empirical bolometric corrections for stars (BC_V), a commonly overlooked fact is that while the zero point is arbitrary, the bolometric magnitude of the Sun (Mbol_Sun) that is used in combination with such tables cannot be chosen arbitrarily. It must be consistent with the zero point of BC_V so that the apparent brightness of the Sun is reproduced. The latter is a measured quantity, for which we adopt the value V_Sun = -26.76 +/- 0.03. Inconsistent values of Mbol_Sun are listed in many of the most popular sources of BC_V. We quantify errors that are introduced by not paying attention to this detail. We also take the opportunity to reprint the BC_V coefficients of the often used polynomial fits by Flower (1996), which were misprinted in the original publication.