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Date and Time of the Query: 2018-11-19 T12:26:14 PST
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For refcode 1995A&AS..114..409B:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
1995A&AS..114..409B Resolved atomic super-clouds in spiral galaxies R. Braun Netherlands Foundation for Research in Astronomy, Postbus 2,7990 AA Dwingeloo, The Netherlands Received February 28; accepted March 23, 1995 Abstract. - High quality data are presented of neutral hydrogen emission and absorption in the fields of eleven of the nearest spiral galaxies. Multi-configuration VLA observations have provided angular resolution of 6 arcsec (corresponding to about 100 pc at the average galaxy distance of 3.5 Mpc) and velocity resolution of 6 km s^-1^, while accurately recovering the total line flux detected previously with filled apertures. Previous experience suggests that this physical resolution is sufficient to at least marginally resolve the HI super-cloud population which delineates regions of active star formation. A high brightness filamentary network of HI super-clouds is seen in each galaxy. Emission brightness temperatures in excess of 200 Kelvin are sometimes detected at large radii, even in relatively face-on systems. All galaxies display a systematic increase in the observed brightness temperature of super- clouds with radius, followed by a flattening and subsequent decline. In the few instances where background continuum sources allow detection of HI absorption, the indicative spin temperatures are consistent with the super-cloud brightness temperature seen in emission at similar radii. These data suggest substantial opacity of the HI in the super-cloud network. Key words: galaxies: ISM - galaxies: kinematics and dynamics - galaxies: spiral - radio lines: galaxies
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