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Morphological Characteristics of Compact High-Velocity Clouds Revealed by High-Resolution WSRT Imaging

Published online by Cambridge University Press:  12 April 2016

W. B. Burton  and
R. Braun
W. B. Burton
Affiliation:
Sterrewacht Leiden, P.O. Box 9513, 2300 RA Leiden, The Netherlands
R. Braun
Affiliation:
Netherlands Foundation for Research in Astronomy, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands

Abstract

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A class of compact, isolated high–velocity clouds which plausibly represents a homogeneous subsample of the HVC phenomenon in a single physical state was objectively identified by Braun and Burton (1999). Six examples of the CHVCs, unresolved in single–dish data, have been imaged with the Westerbork Synthesis Radio Telescope. The high–resolution imaging reveals the morphology of these objects, including a core/halo distribution of fluxes, signatures of rotation indicating dark matter, and narrow linewidths constraining the kinetic temperature of several opaque cores. In these regards, as well as in their kinematic and spatial deployment on the sky, the CHVC objects are evidently a dynamically cold ensemble of dark–matter–dominated H ɪ clouds accreting onto the Local Group in a continuing process of galactic evolution.

Type
Part 2. Properties of Small Groups
Information
International Astronomical Union Colloquium , Volume 174: Small Galaxy Groups , 2000 , pp. 136 - 147
Copyright
Copyright © Astronomical Society of the Pacific 2000

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