NOAO >   Observing Info >   Approved Programs >   2005A-0474

# Proposal Information for 2005A-0474

PI: Beth Willman, New York University, beth.willman@nyu.edu
Address: Center for Cosmology and Particle Physics, 4 Washington Place, Room 424, New York, NY 10003, USA

CoI: Michael Blanton, New York University, CCPP
CoI: David Martinez-Delgado, Max-Planck-Institut fur Astronomie
CoI: David W. Hogg, New York University, CCPP
CoI: Connie Rockosi, University of California, Santa Cruz/Lick Observatory

Title: Two New Ultra-Faint Milky Way Companions: \Large \bf Not Your Average "Building Blocks" \normalsize

Abstract: We propose to obtain deep, wide field imaging of two Milky Way companions, just found in the SDSS. One companion is a likely old, metal-poor outer halo system with an M_V ~ -3.0 and a half light radius of ~20 pc. The second object has not yet been confirmed as a true Milky Way companion, but is a strong candidate for a new outer halo dwarf spheroidal with a total luminosity fainter than any other galaxy yet known. The proposed data will enable i) the measurement of their surface density profiles, ii) the detection of possible multiple stellar populations, and iii) a search for tidal features. Confirmation of the nature of these objects, whether dwarfs or not, will further our understanding of the Milky Way's formation and evolution, as well as of the substructure problem''. The properties of these unprecedented companions will also provide constraints on theories of low mass galaxy formation.

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 NOAO >   Observing Info >   Approved Programs >   2005A-0474