The stellar population and internal kinematics of the Sextans dwarf spheroidal Galaxy

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The Sextans dwarf Spheroidal (dSph) galaxy was discovered recently by Irwin, et al. (1990, M. N. R. A. S., 244, 16p). We report results concerning a number of the global properties of the stellar population of this system. Based on deep CCD photometry obtained with the prime-focus CCD camera on the CTIO 4m telescope, we find that the galaxy is dominated by an old stellar population, similar to that observed in the Draco, Sculptor, and Ursa Minor dwarfs. Some blue stragglers are also present; if these are associated with an intermediate age component, they indicate that only a tiny fraction of the stellar population of Sextans is younger than about 10 Gyr. Based on the apparent magnitude of the predominately red horizontal branch, we conclude that the true distance modulus of Sextans is 19.7 ± 0.3, and the total luminosity of the galaxy is 5.2 × 10⁵L_⊙. A complete description of these results is given in Mateo, et al. (1991, A. J., 101, 892).