The extended structure of the dwarf irregular galaxy Sagittarius

Abstract

We present a detailed study of the stellar and HI 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 ${\mu }_V\simeq 30.0$ mag/arcsec${}^2$, 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 HI distribution. The whole major-axis profile is consistent with a pure exponential, with a scale radius of $\simeq 340$ 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 HI 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 HI 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).

11 pages, 14 figures, accepted for publication on A&A. arXiv admin note: text overlap with arXiv:1404.1697

References in corpus (7)

• The Star Formation Histories of Local Group Dwarf Galaxies I. Hubble Space Telescope / Wide Field Planetary Camera 2 Observations
• The Local Group dwarf Leo T: HI on the brink of star formation
• The performance of the blue prime focus Large Binocular Camera at the Large Binocular Telescope
• Satellite Dwarf Galaxies in a Hierarchical Universe: The Prevalence of Dwarf-Dwarf Major Mergers
• The extended structure of the dwarf irregular galaxies Sextans A and Sextans B. Signatures of tidal distortion in the outskirts of the Local Group
• The Dynamics and Metallicity Distribution of the Distant Dwarf Galaxy VV124
• Near-Infrared photometry of carbon stars in the Sagittarius dwarf irregular galaxy and DDO 210

Cited by in corpus (9)

• Chemistry and Kinematics of the Late-Forming Dwarf Irregular Galaxies Leo A, Aquarius, and Sagittarius DIG
• DUSTiNGS III: Distribution of Intermediate-Age and Old Stellar Populations in Disks and Outer Extremities of Dwarf Galaxies
• Extremely Metal-Poor Galaxies: The Environment
• Astrophysical Distance Scale II. Application of the JAGB Method: A Nearby Galaxy Sample
• Dissecting the stellar content of Leo I: a dwarf irregular caught in transition
• Solo dwarfs II: The stellar structure of isolated Local Group dwarf galaxies
• A Remarkable Oxygen-rich Asymptotic Giant Branch Variable in the Sagittarius Dwarf Irregular Galaxy
• The Isaac Newton Telescope monitoring survey of Local Group dwarf galaxies--V. The star formation history of Sagittarius dwarf irregular galaxy derived from long period variable stars
• The Smallest Scale of Hierarchy Survey (SSH). I. Survey Description