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Stellar Populations of Halo Substructure Along The Major Axis of M31

Published online by Cambridge University Press:  01 December 2006

J. C. Richardson ,
A. M. N. Ferguson ,
R. A. Johnson  and
D. C. Faria
J. C. Richardson
Affiliation:
Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh, UK, EH9 3HJ email: jcr@roe.ac.uk
A. M. N. Ferguson
Affiliation:
Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh, UK, EH9 3HJ email: jcr@roe.ac.uk
R. A. Johnson
Affiliation:
Department of Astrophysics, University of Oxford, Keble Road, Oxford, UK, OX1 3RH
D. C. Faria
Affiliation:
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA
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Abstract

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We present HST/ACS observations of five regions in the outskirts of M31. Four are centered on prominent stellar overdensities roughly aligned with the major axis. Well-populated colour magnitude diagrams (CMDs) show that these fields differ in morphology from the fifth (Minor Axis) field. Comparisons with isochrones present tantalising evidence that they contain a small contingent of very young (≤ 1Gyr) stars, at odds with what may be expected of typical halo populations, suggesting that this low-latitude substructure could feasibly have formed in the disk.

Keywords

galaxies: individual (M31)galaxies: halosgalaxies: stellar contentgalaxies: evolution
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S241: Stellar Populations as Building Blocks of Galaxies , December 2006 , pp. 375 - 376
Copyright
Copyright © International Astronomical Union 2007

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