Late-type stars in M31
Session 32 -- Local Group Galaxies
Display presentation, Tuesday, 9:30-6:30, Heller Lounge Room

## [32.07] Late-type stars in M31

J.P. Brewer (UBC), D.R. Crabtree (DAO), H.B. Richer (UBC)

Using 4-band CCD photometry we have identified carbon stars and M stars in five $7^\prime \times 7^\prime$ fields that lie along the SW semi-major axis of M31. The photometry is being used to investigate the ratio of carbon stars to late-type M giants ([C/M]) in this system. Metallicity is known to play an important role in determining the [C/M] ratio, and we will investigate the effect of M31's metallicity gradient on the [C/M] ratios observed in our fields. The results will be of interest as they will be independent of parent galaxy morphology, hence allowing us to assess the role that other factors, such as star formation rate, play in the determination of the [C/M] ratio.