THE ASTRONOMICAL JOURNAL    VOLUME 110, NUMBER 5, PAGE 2166       NOVEMBER 1995

             VARIABLE STARS IN THE SEXTANS DWARF SPHEROIDAL GALAXY

                                  MARIO MATEO

    Department of Astronomy, 821 Dennison Building, University of Michigan,
                           Ann Arbor, Michigan 48109
                  Electronic mail: mateo@astro.lsa.umich.edu

                               PHILIPPE FISCHER

      AT&T Bell Labs, 600 Mountain Avenue, Murray Hill, New Jersey 07974
  and Department of Astronomy, 821 Dennison Building, University of Michigan,
                           Ann Arbor, Michigan 48109
                    Electronic mail: philf@physics.att.com

                               WOJTEK KRZEMINSKI

            Las Campanas Observatory, Casilla 601, La Serena, Chile
                 Electronic mail: wojtek@sirius.ctio.noao.edu

                                   ABSTRACT

    We describe a survey for variable stars in the Sextans dwarf spheroidal
    (dSph) galaxy based on the analysis of 113 B and 48 V CCD images of
    four fields covering a total area of 18'x18'.  We have identified 44
    variables: 36 RR Lyr star, 6 anomalous Cepheids, one long-period red
    variable, all probable members of Sextans, and one foreground contact
    binary.  We have used the pulsating stars to derive a true distance
    modulus of 19.67 +/- 0.15 for Sextans (or D = 86 +/- 6 kpc), where the
    error is primarily due to uncertainties in the luminosity-metallicity
    relation for RR Lyr stars.  Based on our new data we conclude that
    [Fe/H]_Sex = -1.6 +/- 0.2, somewhat higher than the value from Suntzeff
    et al. [ApJ, 418, 208 (1993)] obtained from the analysis of fiber
    spectroscopy of the near-IR Calcium triplet.  We present a new deep
    color-magnitude diagram for Sextans which reveals the presence of
    anomalous Cepheids in the galaxy.  This young population may represent
    as much as 25% of the total stellar content of Sextans.  We find a
    surprisingly strong correlation between the frequency of anomalous
    Cepheids in dSph galaxies and galaxian luminosity and speculate on the
    possible origin of this strange effect.  The RR Lyr stars in Sextans do
    not exhibit the Oosterhoff dichotomy observed in globular clusters and
    in the Galactic halo field.