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Session 59 - Milky Way, Center & Halo.
Oral session, Tuesday, January 16
Salon del Rey Central, Hilton

[59.05] The Metal-Rich Halo of M31

R. M. Rich, K. Mighell, J. D. Neill (Columbia U.)

We have reduced archival WFPC2 images of the fields adjacent to globular clusters in M31, revealing the stellar populations in fields with galactocentric distance ranging from 5.3 to 19.4 kpc. We compare the field giant branches with the V,I locus of NGC 6553, a Milky Way globular cluster of Solar metallicity. We find that the majority of the stars in these fields are near the Solar metallicity, with no clear sign of an abundance gradient. This confirms the finding by Rich et al. (1995) that the field adjacent to the M31 globular cluster G1 R_GC=40 kpc has a red clump. The field adjacent to the cluster G219, at 19.6 kpc, cannot have more than 15% of its population in metal poor stars. We also find an excess of stars fainter than the red clump, relative to old Galactic globular clusters; this is also in agreement with the luminosity function of the field adjacent to G1 found by Rich et al.\ (1995).

\bigskip \hangindent=2em \hangafter=1 Rich, R.M., Mighell, K.J., Freedman, W., amp; Neill, J.D., 1995, AJ (submitted).

Program listing for Tuesday