We have found evidence for the presence of two distinct ancient stellar components (both ≥10 Gyr old) in the Sculptor dwarf spheroidal galaxy. We used the ESO Wide Field Imager in conjunction with the Very Large Telescope/FLAMES spectrograph to study the properties of the resolved stellar population of Sculptor out to and beyond the tidal radius. We find that two components are discernible in the spatial distribution of horizontal branch stars in our imaging and in the [Fe/H] and Vhel distributions for our large sample of spectroscopic measurements. They can be generally described as a "metal-poor" component ([Fe/H] < -1.7) and a "metal- rich" component ([Fe/H] >0 -1.7). The metal-poor stars are more spatially extended than the metal-rich stars, and they also appear to be kinematically distinct. These results provide insight into the formation processes of small systems in the early universe and the conditions found there. Even this simplest of galaxies appears to have had a surprisingly complex early evolution.

Item Type:	Refereed Article
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Galactic astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Cole, AA (Professor Andrew Cole)
ID Code:	45327
Year Published:	2004
Web of Science® Times Cited:	286
Deposited By:	Physics
Deposited On:	2007-07-10
Last Modified:	2007-07-10
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