Ultra-faint dwarfs and dwarf-spheroidal galaxies: the Andromeda satellites

Journal
Date Issued
2015
Author(s)
Coppola, G.
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Federici, L.
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Di Fabrizio, L.
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Ferguson, A.
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Fusi Pecci, F.
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Contreras, R.
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Abstract
We present preliminary results on the study of the variable stars and the stellar population of the Andromeda IX (And IX) and the Andromeda X (And X) companions of M31. The study is based on g', r' time series photometry that we obtained as part of our ESO Large Program 186.D-2013 at the Gran Telescopio Canarias (GTC, P.I. G. Clementini). More than twenty RR Lyrae stars were discovered in each galaxy and well sampled and accurate light curves were obtained. The color magnitude diagrams (CMDs) obtained by stacking the 23 pairs of g', r' exposures available for each galaxy are ̃ 2 mag deeper than those presently available in the literature. And IX and And X have prominent red giant branches and clearly visible horizontal branches, although both galaxies are rather contaminated by field stars. The CMD of And IX is well fitted by the mean ridge lines of the metal-poor ([Fe/H]=-2.2 dex) Galactic globular cluster NGC 2419. The steepness of And X's red giant branch seems to suggest a metallicity even lower than NGC 2419.

Volume
86
Start page
281
Uri
Url
Issn Identifier
0037-8720
Ads BibCode
2015MmSAI..86..281C
Rights
open.access
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