NOAO >   Observing Info >   Approved Programs >   2006A-0326

# Proposal Information for 2006A-0326

PI: Roelof de Jong, STScI, dejong@stsci.edu
Address: 3700 San Martin Drive, Baltimore, MD 21218, USA

CoI: Harry Ferguson, STScI
CoI: Eric Bell, MPIA
CoI: Julianne Dalcanton, University of Washington
CoI: Anil Seth, University of Washington
CoI: James Bullock, CfA
CoI: Stephane Courteau, Queens University
CoI: Daniel Zucker, MPIA
CoI: Benne Holwerda, STScI

Title: Resolved Stellar Populations of Massive Galaxies

Abstract: We propose to resolve the halo stellar populations of four nearby, massive disk galaxies (NGC 2403, M81, M83, and NGC 4244) using deep observations with MegaCam on the MMT and IMACS on Magellan-I. These observations will provide star counts and color-magnitude diagrams ~1.5 magnitudes below the tip of the Red Giant Branch (RGB) of the halos of each galaxy. We will measure the metallicity distribution functions and stellar density profiles from star counts down to very low average surface brightnesses, equivalent to ~29.5 V-magnitude per square arcsec. Our targets are part of our HST SNAP program and cover a range in galaxy mass, luminosity, and morphology. As function of these galaxy properties this survey will provide: \vspace-2.45mm \beginitemize \listparindent=-1.3mm \itemindent=-1.3mm \itemsep=-1.3mm \item The first systematic study of the radial and isophotal shapes of diffuse stellar halos. \item A comprehensive analysis of halo metallicity distributions as a function of galaxy type and position within the galaxy. \item A sensitive search for tidal streams and halo substructure. \item The first detailed comparative study of stellar populations across outer disk truncations. \enditemize \vspace- 2.45mm We will use these fossil record of the galaxy assembly process locked up in the old stellar populations to test halo formation models within the hierarchical galaxy formation scheme.

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 >   2006A-0326