The acs lcid project: Rr lyrae stars as tracers of old population gradients in the isolated dwarf spheroidal galaxy tucana

Edouard J. Bernard, Carme Gallart, Matteo Monelli, Antonio Aparicio, Santi Cassisi, Evan D. Skillman, Peter B. Stetson, Andrew A. Cole, Igor Drozdovsky, Sebastian L. Hidalgo, Mario Mateo, Eline Tolstoy

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

We present a study of the radial distribution of RR Lyrae variables, which present a range of photometric and pulsational properties, in the dwarf spheroidal galaxy Tucana. We find that the fainter RR Lyrae stars, having a shorter period, are more centrally concentrated than the more luminous, longer period RR Lyrae variables. Through comparison with the predictions of theoretical models of stellar evolution and stellar pulsation, we interpret the fainter RR Lyrae stars as a more metal-rich subsample. In addition, we show that they must be older than about 10 Gyr. Therefore, the metallicity gradient must have appeared very early on in the history of this galaxy.

Original languageEnglish (US)
Pages (from-to)L21-L24
JournalAstrophysical Journal
Volume678
Issue number1 PART 2
DOIs
StatePublished - 2008

Keywords

  • Dwarf
  • Galaxies
  • Horizontal-branch
  • Individual (Tucana)
  • Local Group
  • Other
  • Stars
  • Variables

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