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|a Bregman, Joel N.
|e author
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|a MIT Kavli Institute for Astrophysics and Space Research
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|a Miller, Eric D.
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|a Wakker, Bart P.
|e author
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|a Miller, Eric D
|e author
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|a HIGH-VELOCITY CLOUDS IN THE NEARBY SPIRAL GALAXY M 83
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|b Institute of Physics/American Astronomical Society,
|c 2015-03-05T21:36:32Z.
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|z Get fulltext
|u http://hdl.handle.net/1721.1/95902
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|a We present deep H I 21 cm and optical observations of the face-on spiral galaxy M 83 obtained as part of a project to search for high-velocity clouds (HVCs) in nearby galaxies. Anomalous-velocity neutral gas is detected toward M 83, with 5.6 × 107 M ☉ of H I contained in a disk rotating 40-50 km s-1 more slowly in projection than the bulk of the gas. We interpret this as a vertically extended thick disk of neutral material, containing 5.5% of the total H I within the central 8 kpc. Using an automated source detection algorithm to search for small-scale H I emission features, we find eight distinct, anomalous-velocity H I clouds with masses ranging from 7 × 105 to 1.5 × 107 M ☉ and velocities differing by up to 200 km s-1 compared to the H I disk. Large on-disk structures are coincident with the optical spiral arms, while unresolved off-disk clouds contain no diffuse optical emission down to a limit of 27 r' mag per square arcsec. The diversity of the thick H I disk and larger clouds suggests the influence of multiple formation mechanisms, with a galactic fountain responsible for the slowly rotating disk and on-disk discrete clouds, and tidal effects responsible for off-disk cloud production. The mass and kinetic energy of the H I clouds are consistent with the mass exchange rate predicted by the galactic fountain model. If the HVC population in M 83 is similar to that in our own Galaxy, then the Galactic HVCs must be distributed within a radius of less than 25 kpc.
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|a en_US
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|a Article
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|t Astrophysical Journal
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