The extended structure of the dwarf irregular galaxy Sagittarius

G. Beccari, M. Bellazzini, F. Fraternali, G. Battaglia, S. Perina, A. Sollima, T. A. Oosterloo, V. Testa, S. Galleti

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We present a detailed study of the stellar and H i structure of the dwarf irregular galaxy Sagittarius. We use new deep and wide field photometry to trace the surface brightness profile of the galaxy out to ≃5.0' (corresponding to ≃1600 pc) and down to μV ≃ 30.0 mag/arcsec2, thus showing that the stellar body of the galaxy is much more extended than previously believed, and it is similarly (or more) extended than the overall H i distribution. The whole major-axis profile is consistent with a pure exponential, with a scale radius of ≃340 pc. The surface density maps reveal that the distribution of old and intermediate-age stars is smooth and remarkably flattened out to its edges, while the associated H i has a much rounder shape, is off-centred and presents multiple density maxima and a significant hole. No clear sign of systemic rotation is detectable in the complex H i velocity field. No metallicity gradient is detected in the old and intermediate age population of the galaxy, and we confirm that this population has a much more extended distribution than young stars (age ≲ 1 Gyr). Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under the Program 089.D-0052(A).Table of stellar photometry (IN6) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/570/A78
Originele taal-2English
ArtikelnummerA78
Aantal pagina's11
TijdschriftAstronomy and astrophysics
Volume570
DOI's
StatusPublished - okt-2014
  • Deep VI photometry of Sgr dIrr

    Beccari, G. (Contributor), Bellazzini, M. (Contributor), Fraternali, F. (Contributor), Battaglia, G. (Contributor), Perina, S. (Contributor), Sollima, A. (Contributor), Oosterloo, T. (Contributor), Testa, V. (Contributor) & Galleti, S. (Contributor), University of Groningen, 21-okt-2014

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