The effective temperatures and physical properties of red supergiants : the effects of metallicity.

Abstract

In this thesis I use moderate-resolution optical spectrophotometry and the new MARCS stellar atmosphere models to determine the effective temperatures of 74 red supergiants (RSGs) in our galaxy, 39 RSGs in the Small Magellanic Cloud (SMC), and 36 RSGs in the Large Magellanic Cloud (LMC). The new effective temperature scales derived from these data are significantly warmer than those in the literature. The known distances of these stars allows a critical comparison with modern stellar evolutionary tracks, and the newly derived temperatures and bolometric corrections generally give much better agreement with predictions of massive star evolution for all three of these galaxies. I also use these new temperature scales to demonstrate a correlation between galactic metallicity and the average spectral subtype of a galaxy's RSG population. Research contained in this thesis has been published in part by the Astrophysical Journal, v. 628, p. 973 Research contained in this thesis has been submitted to the Astrophysical Journal for publication in a future volume.