Astronomy and Astrophysics – Astrophysics
13 pages, 3 figures, 1 table; accepted for publication in ApJ Letters
We report the first results from deep ACS imaging of ten classical globular clusters in the far outer regions (15 < R_p < 100 kpc) of M31. Eight of the clusters, including two of the most remote M31 globular clusters presently known, are described for the first time. Our F606W, F814W colour-magnitude diagrams extend ~ 3 magnitudes below the horizontal branch and clearly demonstrate that the majority of these objects are old (> 10 Gyr), metal-poor clusters. Five have [Fe/H] ~ -2.1, while an additional four have -1.9 < [Fe/H] < -1.5. The remaining object is more metal-rich, with [Fe/H] ~ -0.70. Several clusters exhibit the second parameter effect. Using aperture photometry, we estimate integrated luminosities and structural parameters for all clusters. Many, including all four clusters with projected radii greater than 45 kpc, are compact and very luminous, with -8.9 < M_V < -8.3. These four outermost clusters are thus quite unlike their Milky Way counterparts, which are typically diffuse, sub-luminous (-6.0 < M_V < -4.7) and more metal-rich (-1.8 < [Fe/H] < -1.3).
Ferguson Annette M. N.
ACS photometry of newly-discovered globular clusters in the outer halo of M31 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.If you have personal experience with ACS photometry of newly-discovered globular clusters in the outer halo of M31, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ACS photometry of newly-discovered globular clusters in the outer halo of M31 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-241221