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- The outer halo globular clusters of M31
- Alves-Brito, Alan; Forbes, Duncan A.; Mendel, Jon T.; Hau, George K. T.; Murphy, Michael T.
- We present Keck/HIRES spectra of three globular clusters in the outer halo of M31, at projected distances beyond approximate to 80 kpc from M31. The measured recession velocities for all three globular clusters confirm their association with the globular cluster system of M31. We find evidence for a declining velocity dispersion with radius for the globular cluster system. Their measured internal velocity dispersions, derived virial masses and mass-to-light ratios are consistent with those for the bulk of the M31 globular cluster system. We derive old ages and metallicities which indicate that all three belong to the metal-poor halo globular cluster subpopulation. We find indications that the radial gradient of the mean metallicity of the globular cluster system interior to 50 kpc flattens in the outer regions, however it is still more metal-poor than the corresponding field stars at the same (projected) radius.
- Publication type
- Journal article
- Research centre
- Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
- Monthly Notices of the Royal Astronomical Society: Letters, Vol. 395, no. 1 (May 2009), pp. L34-L38
- Publication year
- Galactic halo; Globular clusters; Invidividual galaxies; Metallicity distribution; Milky-way; Photometry; Spectra; Star galaxies; Stars; Stellar populations
- Wiley-Blackwell Publishing
- Publisher URL
- Copyright © 2009 The Authors. Journal compilation copyright © 2009 RAS. Author's version of the paper reproduced here in accordance with the copyright policy of the publisher.
- Full text
- Peer reviewed