The outer halo globular clusters of M31

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Forbes, Duncan A.

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The outer halo globular clusters of M31

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/52885

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Title: The outer halo globular clusters of M31
Author(s): Alves-Brito, Alan; Forbes, Duncan A.; Mendel, Jon T.; Hau, George K. T.; Murphy, Michael T.
Abstract: 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
Source: Monthly Notices of the Royal Astronomical Society: Letters, Vol. 395, no. 1 (May 2009), pp. L34-L38
Publication year: 2009
Keyword(s): Galactic halo; Globular clusters; Invidividual galaxies; Metallicity distribution; Milky-way; Photometry; Spectra; Star galaxies; Stars; Stellar populations
Publisher: Wiley-Blackwell Publishing
ISSN: 0035-8711
Publisher URL: http://dx.doi.org/10.1111/j.1745-3933.2009.00636.x
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