Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART
Abstract
We have found evidence for the presence of two distinct ancient stellar components (both geq 10 Gyr old) in the Sculptor dwarf spheroidal galaxy. We used the ESO Wide Field Imager (WFI) in conjunction with the VLT/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 v_hel 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]> -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 an important 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.
Keywords
Cite
@article{arxiv.astro-ph/0411029,
title = {Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART},
author = {Eline Tolstoy and M. J. Irwin and A. Helmi and G. Battaglia and P. Jablonka and V. Hill and K. A. Venn and M. D. Shetrone and B. Letarte and A. A. Cole and F. Primas and P. Francois and N. Arimoto and K. Sadakane and A. Kaufer and T. Szeifert and T. Abel},
journal= {arXiv preprint arXiv:astro-ph/0411029},
year = {2009}
}
Comments
accepted for publication in ApJL 12 pages, 4 figures