NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-20 T00:33:26 PDT
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For refcode 2016AJ....151..136H:
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2016AJ....151..136H Young Star Clusters in the Outer Disks of LITTLE THINGS Dwarf Irregular Galaxies Hunter, Deidre A.; Elmegreen, Bruce G.; Gehret, Elizabeth Abstract. We examine FUV images of the LITTLE THINGS sample of nearby dwarf irregular (dIrr) and Blue Compact Dwarf galaxies to identify distinct young regions in their far outer disks. We use these data, obtained with the Galaxy Evolution Explorer satellite, to determine the furthest radius at which in situ star formation can currently be identified. The FUV knots are found at distances from the center of the galaxies of 1--8 disk scale lengths and have ages of <=slant 20 Myr and masses of 20 M{}_o_ to 1 x 10^5^M{}_o_. The presence of young clusters and OB associations in the outer disks of dwarf galaxies shows that dIrrs do have star formation taking place there in spite of the extreme nature of the environment. Most regions are found where the H I surface density is ~1 M{}_o_ pc^-2^, though both the H I and dispersed old stars go out much further. This limiting density suggests a cutoff in the ability to form distinct OB associations and perhaps even stars. We compare the star formation rates in the FUV regions to the average rates expected at their radii and beyond from the observed gas, using the conventional correlation for gas-rich regions. The localized rates are typically 10% of the expected average rates for the outer disks. Either star formation in dIrrs at surface densities \lt 1 {M}_o_ pc^-2^ occurs without forming distinct associations, or the Kennicutt--Schmidt relation over-predicts the rate beyond this point. In the latter case, the stellar disks in the far-outer parts of dIrrs result from scattering of stars from the inner disk. Key words: galaxies: irregular, galaxies: star formation =========================================================================== 2017AJ....153...48H Erratum: "Young Star Clusters in the Outer Disks of LITTLE THINGS Dwarf Irregular Galaxies" (2016, AJ, 151, 136) Hunter, Deidre A.; Elmegreen, Bruce G.; Gehret, Elizabeth Abstract. {see text} ===========================================================================
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