M. Drout Abstract

The Yellow Supergiant Content of the Magellanic Clouds

M. Drout (Harvard University), P. Massey, and K. Neugent

Yellow supergiants (YSGs) are evolved massive stars whose numbers and luminosities on the HR diagram can provide stringent tests for models of massive star evolution.  Previous studies identified large discrepancies between the relatively number of yellow supergiants observed as a function of mass and those predicted by evolutionary models - emphasizing their importance. Unfortunately, identifying these stars is difficult because this portion of the color-magnitude diagram is heavily contaminated by foreground dwarfs.  However, with use of the CTIO facilities we obtained spectra of over 2000 YSG candidates in the Magellanic Clouds, allowing us to identify bona-fide supergiants via their radial velocities.  I will summarize our findings and discuss where they fall within our broader goal of characterizing the massive star content of local group galaxies from one side of the HR diagram to the other.