AAS 205th Meeting, 9-13 January 2005
Session 141 Our Friendly Neighbors: M31 and M33
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

Previous   |   Session 141   |   Next

[141.15] A Spectroscopic Survey of M31 Red Giants with Keck/DEIMOS: Insights into the Progenitor of the Giant Southern Stream

P. Guhathakurta, K. Gilbert, J. Kalirai (UCSC), A. Font, K. Johnston (Wesleyan U.), M. Cooper (UCB), C. Luine (UCSC), S. Majewski, J. Ostheimer (UVa), D. Reitzel, R. M. Rich (UCLA)

We present new results from an ongoing imaging and spectroscopic survey of red giant branch stars in the giant southern tidal stream in M31. Keck/DEIMOS spectra of bright red giants are used to study stellar kinematics and chemical abundance patterns. These data are complemented by deep, wide-field imaging/photometry obtained with CFHT/MegaCam and Subaru/SuprimeCam which allow us to study faint red giants in the stream and to probe its detailed spatial structure (also see poster by S. Majewski et al.) and its contrast against the smooth virialized halo population. A combination of spectroscopic and photometric criteria is used to isolate M31 red giants from foreground Milky Way dwarf star contaminants (see poster by K.M. Gilbert et al. for details). Based on our measurement of the line-of-sight velocity dispersion and metallicity of the stream, we conclude that its progenitor must have been a fairly luminous dwarf satellite galaxy. A series of numerical experiments is used to constrain the orbit of the stream's progenitor.

Data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. We are grateful to the DEIMOS instrument team at UCSC. This work is supported both by NSF grant AST-0307966.

Previous   |   Session 141   |   Next

Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.