Stellar velocities in the Carina, Fornax, Sculptor, and Sextans dsph galaxies: Data from the magellan/MMFS survey

Matthew G. Walker, Mario Mateo, Edward W. Olszewski

Research output: Contribution to journalArticle

156 Scopus citations

Abstract

We present spectroscopic data for individual stars observed from 2004 March through 2008 August as part of our Michigan/MIKE Fiber System (MMFS) survey of four dwarf spheroidal (dSph) galaxies: Carina, Fornax, Sculptor, and Sextans. Using MMFS at the Magellan/Clay Telescope at Las Campanas Observatory, we have acquired 8855 spectra from 7103 red-giant candidates in these Galactic satellites. We list measurements of each star's line-of-sight velocity (median error 2.1 km s-1) and spectral line indices for iron and magnesium absorption features. We use globular cluster spectra to calibrate the indices onto standard [Fe/H] metallicity scales, but comparison of the resulting metallicities with published values suggests that the MMFS indices are best used as indicators of relative, not absolute, metallicity. The empirical distributions of velocity and spectral indices also allow us to quantify the amount of contamination by foreground stars. In a companion paper, we develop an algorithm that evaluates the membership probability for each star, showing that the present MMFS sample contains more than 5000 dSph members, including 774 Carina members, 2483 Fornax members, 1365 Sculptor members, and 441 Sextans members.

Original languageEnglish (US)
Pages (from-to)3100-3108
Number of pages9
JournalAstronomical Journal
Volume137
Issue number2
DOIs
StatePublished - Jun 8 2009

Keywords

  • Dwarf galaxies
  • Galaxies
  • Individual (Carina, Fornax, Sculptor, Sextans) galaxies
  • Kinematics and dynamics Local Group techniques
  • Radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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