NOAO >   Observing Info >   Approved Programs >   2001A-0264

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Proposal Information for 2001A-0264


PI: Mario Mateo, Univ of Michigan, mateo@astro.lsa.umich.edu
Address: 814 Dennison, Ann Arbor, MI 48109-1090, USA

CoI: Heather Morrison, Case Western Reserve U, Astronomy
CoI: Ed Olszewski, Steward Obs
CoI: John Arabadjis, University of Michigan Astronomy Dept
CoI: Robbie Dohm-Palmer, U Arizona and U Mich Astronomy Dept
CoI: Ken Freeman, Mt Stromlo and Siding Springs Obs
CoI: Paul Harding, Steward Obs/Case Western Reserve
CoI: John Norris, Mt Stromlo and siding Springs Obs
CoI: Chris Sneden, U Texas, Austin, Astronomy
CoI: Amina Helmi, Wherever

Title: Searching for Substructure in the Galactic Halo -\phantomxxxxxxxx The Imaging Survey

Abstract: There is growing evidence that the Galactic halo contains considerable substructure, but the detailed distribution of this structure and its fractional contribution to the halo remains poorly constrained. We have undertaken a large survey to identify and quantify the degree of kinematic substructure of the halo. The key first step of this effort is a photometric survey to identify halo field stars. We use a form of the Washington photometric system to identify candidate halo red giants, blue horizontal branch stars and halo main sequence turnoff stars. Over the past year of 4m imaging, we have enjoyed success in finding distant halo giants; our sample has significantly increased the number of known field red giants out to distances of 150- 200 kpc from the sun. We have also begun kinematic studies of halo turnoff stars identified from these data. We propose additional imaging at CTIO and KPNO to survey 100 deg^2 by the end of 2001. Models of an accreted halo suggest that a survey this size can identify multiple stream even if only 25% of the halo was formed by the accretion of small fragments. We may be seeing the first signs of substructure in our imaging data and in our kinematic observations of halo dwarfs.


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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