Abstract
Three high-velocity clouds (HVCS) with very large negative velocities have been surveyed in the 21-cm hydrogen line with an angular resolution of 12 arcmin and a velocity resolution of 1.8 km/s, in order to study their fine structure. Despite their high velocities, two of these clouds show the same two-component structure as northern HVCS. The 21-cm line profiles show broad velocity components throughout the clouds, and narrow velocity components which are seen only in small cores near the emission peaks. The core of one of the clouds is found to be in rapid rotation, suggesting it was formed as a condensation within the cloud. An upper limit of 500 K is obtained on the kinetic temperature of the gas in this core. The broad velocity components in all three clouds show smooth, systematic velocity patterns across the clouds. The velocity widths of both the narrow and the broad velocity components are found to be constant across the clouds, to within the errors of measurement. The observations are compared with recent studies of fine structure in other HVCS and in the Magellanic Stream.
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