NOAO >   Observing Info >   Approved Programs >   2009B-0421

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Proposal Information for 2009B-0421


PI: Annette Ferguson, Institute for Astronomy, ferguson@roe.ac.uk
Address: University of Edinburgh, Blackford Hill, Edinburgh, Midlothian EH3 5AB, UK

CoI: Pauline Barmby, University of Western Ontario
CoI: Pat Cote, Herzberg Institute for Astrophysics
CoI: Bill Harris, McMaster Unniversity
CoI: Avon Huxor, University of Bristol
CoI: Dougal Mackey, University of Edinburgh
CoI: Thomas Puzia, Herzberg Institute for Astrophysics

Title: Radial Velocity and Metallicity Determinations for Remote Globular Clusters in M31 and M33

Abstract: We propose to determine radial velocities and metallicities for a sample of ~ 20 remote globular clusters (GCs) which we have discovered in the outer halos of the Local Group galaxies M31 and M33. Most of these objects have been uncovered in the course of the PAndAs survey, an international collaboration which is using CFHT/MegaPrime to map more than 300 square degrees in the g and i bands around M31 and M33. The target clusters, all of which have been identified from high- quality imaging (typically \lesssim 0.8'' seeing), lie at projected radii of up to 130 kpc from M31 and 30 kpc from M33 and thus lie significantly beyond all previously-known GCs in these systems. Rather intriguingly, many of the new discoveries exhibit either possible associations with halo tidal streams, or show unusual spatial anisotropies with respect to their host galaxy. Velocity and metallicity data for these objects will provide a detailed characterization of the ensemble properties of the outer halo GC populations, and, through the search for kinematic and metallicity correlations within groups of GCs, help determine what fraction of these objects can be attributed to either late or ongoing accretion events. Ultimately, these data will also provide a basis for improved dynamical mass estimates of both galaxies.


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