Improved properties for cool stars

Colors are tabulated for Johnson U-V and B-V, Cousins V-R and V-I, Johnson-Glass V-K, J-K, and H-K, and CIT/CTIO V-K, J-K, H-K, and CO. We have developed these color-temperature relations by convolving synthetic spectra with the best-determined, photometric filter transmission profiles.

The synthetic spectra have been computed with the SSG spectral synthesis code (Bell & Gustafsson 1978; Gustafsson & Bell 1979) using MARCS stellar atmosphere models (Gustafsson et al. 1975; Bell et al. 1976) as input. Both of these codes have been improved substantially, especially at low temperatures, through the incorporation of new opacity data. The resulting synthetic colors have been put onto the observational systems by applying color calibrations derived from models and photometry of field stars that have effective temperatures determined by the infrared flux method.