NOAO >   Observing Info >   Approved Programs >   2007B-0412

# Proposal Information for 2007B-0412

PI: Steven R. Majewski, University of Virginia, srm4n@virginia.edu
Address: Department of Astronomy, PO Box 400325, Charlottesville, VA 22904-4325, USA

CoI: Richard J. Patterson, U Virginia
CoI: Puragra Guhathakurta, UC-Santa Cruz
CoI: Peter Frinchaboy, U Wisconsin
CoI: Jason Kalirai, UC-Santa Cruz
CoI: Rachael Beaton, U Virginia
CoI: Karrie Gilbert, UC-Santa Cruz

Title: Exploring the Newly Discovered Halo Of M31

Abstract: Cold dark matter structure formation models make specific predictions about the shape, extent and smoothness of halos, but few halos outside the Milky Way's (MW) have been explored for even the most basic, global properties; even the MW halo presents some difficulties for study from within. M31 offers a global external perspective and yet is close enough for us to resolve individual stars. Recently, using Mayall 4-m + Mosaic photometry in the Washington M, T_2 + DDO51 filters and follow-up spectroscopy of identified M31 giant candidates, we made the first direct and unambiguous detection of the M31 halo, and traced its projected r^-2 density profile to 150 kpc along the minor axis. Now we propose to (1) expand this systematic study of the extent, shape, smoothness, and chemodynamics of the newly found M31 halo to the more challenging, virtually ignored northern side of M31, (2) check whether there is an M33 halo and clarify how it overlaps the M31 halo, (3) continue to identify new M31 halo streams/substructure, and (4) use the most extensive angular coverage of M31 yet created (diameter 24\deg) to make the first measure of the M31 \it proper motion. This first study of the dynamics, kinematical substructure and metallicity gradient of the M31 halo to (mu)_V$>$35 mag arcsec^-2 will provide direct constraints on hierarchical formation models.

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

 NOAO >   Observing Info >   Approved Programs >   2007B-0412