Talk Title: 'Sculptor'-ing the Galaxy? The Chemical Compositions of Red Giants in the Sculptor Dwarf Spheroidal Galaxy
Abstract: Presenter: Doug Geisler, Departamento de Fisica, Universidad de Concepci\'on, Casilla 160-C, Concepci\'on, Chile;
Co-I's: Verne V. Smith, Department of Physics, University of Texas El Paso, El Paso, TX 79968 USA; George Wallerstein, Astronomy Department, University of Washington, Seattle, WA 98195 USA; Guillermo Gonzalez, Department of Physics \& Astronomy, Iowa State University, Ames, IA 50011-3160 USA; Corinne Charbonnel, Observatoire de Midi-Pyrenees, 14 Avenue Edouard Belin, Toulouse, F-31400, France
Abstract: We use high-resolution, high S/N spectra obtained with the VLT and UVES to determine abundances in 4 red giants in the Sculptor dwarf spheroidal galaxy. We have combined our data with similar data for 5 Sculptor giants studied recently to form a large sample with a wide metallicity range, allowing us to establish trends of [X/Fe] with [Fe/H] for many elements, X. The trends are significantly different from the trends seen in Galactic halo stars. The many discrepancies that our halo cannot be made up in bulk of stars similar to those in Sculptor, corroborating similar conclusions reached by Shetrone et al., Fulbright and Tolstoy et al. In contrast to the suggestion of Shetrone et al., it appears unlikely that a substantial fraction of even the \mr halo could have been constructed by the accretion of dwarf spheroidal stars like those in our sample. If less massive dwarf spheroidal-like objects similar to Sculptor were accreted to form much of the halo, they must have been accreted very early, before the onset of SNIa. >From comparison with models we find that the star formation rate in Sculptor was a factor of 5 or more lower on average than that in our Galaxy. We also find a heavy element-rich star in our sample. This star and the [Ba/Eu] trend we see indicates that AGB stars must have played an important role in the evolution of the s-process elements in Sculptor.
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