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Andromeda and the Seven Dwarfs

Published online by Cambridge University Press:  11 July 2011

C. Brasseur
Affiliation:
Max-Planck-Institut für Astronomie, 17 Königstuhl, 69117 Heidelberg, Germany
H.-W. Rix
Affiliation:
Max-Planck-Institut für Astronomie, 17 Königstuhl, 69117 Heidelberg, Germany
N. Martin
Affiliation:
Max-Planck-Institut für Astronomie, 17 Königstuhl, 69117 Heidelberg, Germany
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Abstract

With the new generation of wide-field surveys, our understanding of the Andromeda satellite system has dramatically improved in recent years. Since 2004, 12 new dwarf galaxies have been discovered around Andromeda, doubling the number of previously known companions. What are the properties of these newly discovered dwarfs and what do they tell us about galaxy formation? Are these systems bound? Do they show evidence of multiple star formation epochs? To better understand the stellar populations of the faintest dwarfs around M 31, we have used the Large Binocular Camera (LBT) and Suprime-Cam (Subaru) to obtain photometric observations of And X, And XVII, And XVIII, And XIX, And XX, And XXI and And XXII. Reaching below the horizontal branch, these observations have allowed for accurate distance determinations to be made, together with metallicity estimates based on the red giant branch stars. Our analysis shows our 7 dwarfs to be metal poor and with large spreads in [Fe/H], it strongly suggests multiple generations of stars are present in And X, And XVII, And XVIII, and And XIX, And XXI.

Type
Research Article
Copyright
© EAS, EDP Sciences, 2011

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References

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