NOAO >   Observing Info >   Approved Programs >   2009B-0199

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Proposal Information for 2009B-0199


PI: Edward W. Olszewski, U of Arizona, eolszewski@as.arizona.edu
Address: Steward Obs, 933 N Cherry, Tucson, AZ 85721, USA

CoI: Abi Saha, NOAO
CoI: Tim Axelrod, Univ of Arizona

Title: An Efficient Search for Extratidal Structure in Globular Clusters

Abstract: We have found an unprecedented extra-tidal, azimuthally smooth, halo- like difffuse spatial extension of the globular cluster NGC 1851, from persistence of its main-sequence CMD out to at least 6 tidal radii. Since such wide field deep data do not exist around many other GC's, we do not know if this is common or rare. The structure is not what shock heating or tidal models lead us to expect: i.e. existing simulations are inadequate. Claims in the literature for extended structure (of any kind) around other GC's are often tenuous, and sometimes demonstrably wrong. Archival data (CFHT, SDSS etc) are of limited use for a systematic investigation of extra-tidal structure. We therefore propose to observe a sample of 17 GC's in the southern skies (where most GC's reside) to look for analogs of NGC 1851. We will supplement our findings with analysis of available archival data of northern GC's. Such data will confront theoreticians to produce more exhaustive models and simulations of processes that can lead to the kind of structure we have found around NGC 1851.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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