Keck Studies of M31's Stellar Halo

Abstract

We present Keck 10-meter/LRIS spectra of candidate red giants in the halo of M31, located at a projected radius of R=19kpc on the minor axis. These spectroscopic targets have been selected using a combination of UBRI-based and morphological screening to eliminate background galaxies. Radial velocity measurements are used to separate M31 halo giants from foreground Milky Way dwarf stars, M31 disk stars, and residual background galaxies. The metallicity of each M31 halo giant is measured using standard photometric and spectroscopic techniques, the latter based on the strength of the CaII triplet. The various [Fe/H] estimates are in rough agreement with one another. The data reveal a large spread (>2dex) in [Fe/H] in M31's halo; there is no strong radial [Fe/H] gradient. LRIS and HIRES spectra are also presented for red giants in five dwarf spheroidal satellites of M31: AndI, AndIII, AndV, AndVI, and AndVII. There appears to be a significant metallicity spread in AndVI and possibly in AndI. The new radial velocity data on these outer dwarfs are used to constrain the total mass of M31: the best estimate is under 10^(12)Msun, somewhat less than the best estimate for the Milky Way.

12 pages, 7 figures, Proceedings of SPIE Conference: Discoveries and Research Prospects with 8-10 Meter Class Telescopes (Munich March 2000)

References in corpus (4)

• The Mass of the Andromeda Galaxy
• Dynamical Mass Estimates for the Halo of M31 from Keck Spectroscopy
• Internal Kinematics of the Andromeda II Dwarf Spheroidal Galaxy
• Abundances of Red Giants in the Andromeda II Dwarf Spheroidal Galaxy

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• Complexity on Small Scales: The Metallicity Distribution of the Carina Dwarf Spheroidal Galaxy
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• The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV dSphs
• The Anisotropic Distribution of M 31 Satellite Galaxies: A Polar Great Plane of Early-Type Companions
• Formation of the Galactic stellar halo I. Structure and kinematics
• Dynamical Mass Estimates for the Halo of M31 from Keck Spectroscopy
• The Andromeda Project. I. Deep HST-WFPC2 V,I photometry of 16 fields toward the disk and the halo of the M31 galaxy. Probing the stellar content and metallicity distribution
• Metallicity and Kinematics of M31's Outer Stellar Halo from a Keck Spectrocscopic Survey
• WIYN Survey for Carbon Stars in the M31 and Cetus Dwarf Spheroidal Galaxies: Evolutionary Implications
• The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI
• The SPLASH Survey: A Spectroscopic Analysis of the Metal-Poor, Low-Luminosity M31 dSph Satellite Andromeda X
• Local Group(s)