The recent star formation in NGC 6822 from HST imaging

Abstract

We present HST WFPC2 and STIS imaging of the low metallicity galaxy NGC 6822, performed as part of a study of the young stellar populations in the galaxies of the Local Group. Eleven WFPC2 pointings, with some overlap, cover two regions, extending over 19'x19' and 13'x13' respectively, off the galaxy center. One 25x25'' field observed with STIS' FUV- and NUV- MAMA, includes Hodge's OB8 association and the HII region Hubble V. We derive the physical parameters of the stars in the fields and the extinction by comparing the photometry to grids of model magnitudes. The environments studied in this work include one of the most luminous (in Halpha) HII regions in the Local Group (Hubble V) with a compact star cluster, a typical OB association (OB15), the sparse field population and the outskirts of NGC6822. The color-magnitude diagrams show similar ages of few Myrs for both OB8 and OB15. The density [per unit area] of hot massive stars in the core of the OB8 association is higher than in OB15 by a factor of 12, while the total stellar mass formed is similar. In both OB15 and OB8 massive star candidates are found. The average extinction is found to vary among the three environments studied: E(B-V) = 0.22 in the outer regions, E(B-V) = 0.27 in the fields East of the galaxy main bar, and E(B-V) = 0.40 in the HII region Hubble V. A quantitative discussion of the applicability of the reddening-free-index method for photometric determination of stellar parameters is provided for the filters used in this work, based on our grids of stellar models.

arXiv comment20 pages, 11 figures, 4 tables In press (AJ 2006 July issue)

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Cited by in corpus (10)

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• Bright OB stars in the Galaxy IV. Stellar and wind parameters of early to late B supergiants
• Physical Properties of Molecular Clouds at 2 parsec Resolution in the Low-Metallicity Dwarf Galaxy NGC 6822 and the Milky Way
• Statistical Properties of the GALEX/SDSS matched source catalogs, and classification of the UV sources
• An Ultraviolet Study of Star-Forming Regions in M31
• The cluster birthline in M33
• The Recent Star Formation in NGC 6822: an Ultraviolet Study
• The initial mass function and star formation law in the outer disc of NGC 2915
• Multiwavelength study of the star formation in the bar of NGC 2903
• The Initial Mass Function in the Extended Ultraviolet Disk of M83