Abstract
Color-temperature relations are a necessary ingredient in addressing many
astrophysical problems. They are especially important when using isochrones
to age-date star clusters, since the isochrones must first be transformed from
the theoretical (log Te, log L) to the observational (color, magnitude)
plane before they can be compared to stellar photometry. As part of our galaxy
population synthesis program, we have calculated the transformation relations
required to put the raw synthetic colors - colors measured from synthetic
spectra using commonly-accepted filter transmission profiles - onto the
observed photometric systems. In this poster, we present the color
transformations that we have derived from synthetic spectra of a group of
F1-K5 stars which have well-determined effective temperatures, surface
gravities and metallicities. The effective temperatures of most of these stars
were estimated by Bell & Gustafsson (1989) using the infrared flux method, and
their adopted temperature scale is confirmed in a companion poster (Bell &
Houdashelt) using the recent angular diameter measurements of Mozurkewich. We
demonstrate the necessity and effectiveness of the derived color transformations
by applying them to a 4 Gyr, solar-metallicity isochrone and comparing the
results to various color-magnitude diagrams of the Galactic open cluster M67.
The color-temperature relations which result after the synthetic colors have
been transformed to the observational systems are also compared to previous
determinations.
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