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E. K. Grebel, M. Odenkirchen, D. Harbeck (MPIA)
Imaging data from the Sloan Digital Sky Survey (SDSS) were used to study the structure of the dwarf spheroidal galaxy Sextans, a nearby Milky Way companion. The overall distribution of stars is approximately ellipsoidal with a mean eccentricity of 0.35. The radial stellar density profile is well fit by a King profile over three orders of magnitude. The King profile has a concentration parameter of 0.98 and yields a limiting radius of 160' in good agreement with earlier studies. There is no obvious evidence for the presence of a pronounced extratidal component around Sextans. The spatial distribution of stars within this low-density galaxy is slightly asymmetric and shows a slight density enhancement on the southern and south-western part. These findings stand in contrast to our recent SDSS study of the nearby dwarf spheroidal galaxy Draco, which was found to have a very regular and symmetric structure and to be 40% more extended than previously thought (Odenkirchen et al. 2001, AJ, 122, 2538). The red horizontal branch stars in Sextans are more strongly centrally concentrated than the extended distribution of blue horizontal branch stars, confirming the population gradient found earlier within a smaller field centered on Sextans (Harbeck et al. 2001, AJ, 122, 3092).
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.