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Published December 2010 | Published + Accepted Version
Journal Article Open

Multi-element Abundance Measurements from Medium-resolution Spectra. II. Catalog of Stars in Milky Way Dwarf Satellite Galaxies


We present a catalog of Fe, Mg, Si, Ca, and Ti abundances for 2961 stars in eight dwarf satellite galaxies of the Milky Way (MW): Sculptor, Fornax, Leo I, Sextans, Leo II, Canes Venatici I, Ursa Minor, and Draco. For the purposes of validating our measurements, we also observed 445 red giants in MW globular clusters and 21 field red giants in the MW halo. Themeasurements are based on Keck/DEIMOS medium-resolution spectroscopy (MRS) combined with spectral synthesis. We estimate uncertainties in [Fe/H] by quantifying the dispersion of [Fe/H] measurements in a sample of stars inmonometallic globular clusters (GCs).We estimate uncertainties in Mg, Si, Ca, and Ti abundances by comparing to high-resolution spectroscopic abundances of the same stars. For this purpose, a sample of 132 stars with published high-resolution spectroscopy in GCs, the MW halo field, and dwarf galaxies has been observed with MRS. The standard deviations of the differences in [Fe/H] and ([α/Fe]) (the average of [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]) between the two samples is 0.15 and 0.16, respectively. This catalog represents the largest sample of multi-element abundances in dwarf galaxies to date. The next papers in this series draw conclusions on the chemical evolution, gas dynamics, and star formation histories from the catalog presented here. The wide range of dwarf galaxy luminosity reveals the dependence of dwarf galaxy chemical evolution on galaxy stellar mass.

Additional Information

© 2010 American Astronomical Society. Received 2010 March 7; accepted 2010 October 26; published 2010 November 30. Data herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors thank the referee, Piercarlo Bonifacio, for his thoughtful suggestions, which improved this manuscript. We gratefully acknowledge Sandra Faber, Ricardo Schiavon, and Michael Cooper of the DEEP2 team for acquiring Keck/DEIMOS spectroscopy of bright Milky Way halo field stars during nights of poor transparency. We also thank Peter Stetson for providing additional globular cluster photometry and Bob Kraft for helpful discussions and for providing some of the globular cluster spectroscopy for this work. The generation of synthetic spectra made use of the University of California Santa Cruz Pleiades supercomputer and the Yale High Performance Computing cluster Bulldog. We thank Joel Primack for sharing his allocation of Pleiades supercomputer time and Mario Jurić for a helpful discussion on the mass of the components of the Milky Way. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF-01233.01 awarded to E.N.K. by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. P.G. acknowledges NSF grants AST-0307966, AST-0607852, and AST-0507483. MG acknowledges support from NSF grant AST-0908752. C.S. acknowledges NSF grant AST-0909978. J.G.C. acknowledges NSF grant AST-090109. M.H.S. was supported at PSU by NASA contractNAS5-00136. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the support of the Canadian Space Agency. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facility: Keck:II (DEIMOS)

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Published - Kirby2010p12845Astrophys_J_Suppl_S.pdf

Accepted Version - 1011.4516.pdf


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