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Andromeda and the seven dwarfs

Published online by Cambridge University Press:  08 November 2005

Alan McConnachie ,
Mike Irwin ,
Scott Chapman ,
Rodrigo Ibata ,
Annette Ferguson ,
Geraint Lewis  and
Nial Tanvir
Alan McConnachie
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, U.K. email: alan@ast.cam.ac.uk
Mike Irwin
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, U.K. email: alan@ast.cam.ac.uk
Scott Chapman
Affiliation:
California Institute of Technology, Pasadena, CA, 91125
Rodrigo Ibata
Affiliation:
Observatoire de Strasbourg, 11, rue de l'Universite, F-67000, Strasbourg, France
Annette Ferguson
Affiliation:
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, U.K.
Geraint Lewis
Affiliation:
Institute of Astronomy, School of Physics, A29, University of Sydney, NSW 2006, Australia
Nial Tanvir
Affiliation:
Physical Sciences, Univ. of Hertfordshire, Hatfield, AL10 9AB, U.K.
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Abstract

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The satellite system of M31 is the next closest satellite system to our own, and is well within reach of current generations of ground-based instrumentation. We have conducted a survey of this system with the Isaac Newton Telescope Wide Field Camera, particularly focussing on the seven dwarf spheroidal companions, and derived homogeneous, fundamental information for them. This reveals the presence of severe tidal distortion and multiple structural components in some systems. In addition, a comparison of the M31 dwarf spheroidals to their Galactic counterparts shows that the M31 dwarf spheroidals have scale radii generally twice as large as the Galactic dwarfs, suggesting that the tidal field of M31 may be substantially weaker than that for the Galaxy. A Keck/DEIMOS study of the newly discovered satellite And IX suggests that this galaxy has an anomalously large metallicity for its luminosity, and shows it to be strongly dark matter dominated.

Keywords

(galaxies:) Local Groupgalaxies: dwarfgalaxies: stellar contentgalaxies: structuregalaxies: kinematics and dynamics
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 1 , Colloquium C198: Near-Field Cosmology with Dwarf Elliptical Galaxies , March 2005 , pp. 84 - 91
Copyright
© 2005 International Astronomical Union