Str{ö}mgren Color-Temperature Relations for Cool Stars

Abstract

A new extensive grid of synthetic Str{ö}mgren colors and bolometric corrections is presented for F-M type dwarf and giant stars having 3000K $\le$ T${}_{\mathrm{eff}}$ $\le$ 8000K, 0.0 $\le$ log $g$ $\le$ 5.0, and -3.0 $\le$ [Fe/H] $\le$ 0.5. These purely theoretical colors are placed on the observational system using color calibrations derived from $uvby$ photometry of nearby field stars having $Hipparcos$ parallaxes and effective temperatures determined by the infrared flux method. Modern isochrones transformed to the observed plane using the resultant color-temperature relations are able to reproduce the $uvby$ color-magnitude diagrams of several open and globular clusters (notably M 67, M 92, and 47 Tuc) quite satisfactorily.

4 pages, 4 figures, to be published in "Observed HR diagrams and stellar evolution: the interplay between observational constraints and theory" (Coimbra, June, 2001) ASP Conf. Ser., 2001, T. Lejeune and J. Fernandes, eds