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Author Bregman, J. N.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ REGIONS ♦ VELOCITY ♦ MILKY WAY ♦ HYDRODYNAMICS ♦ COSMIC GASES ♦ MAGNETIC FIELDS ♦ RADIATION FLUX ♦ RADIATIVE COOLING ♦ ROTATION ♦ STAR CLUSTERS ♦ SUPERNOVAE ♦ THERMAL CONDUCTIVITY ♦ X RADIATION ♦ COOLING ♦ COSMIC RADIO SOURCES ♦ ELECTROMAGNETIC RADIATION ♦ ERUPTIVE VARIABLE STARS ♦ FLUID MECHANICS ♦ FLUIDS ♦ GALAXIES ♦ GASES ♦ IONIZING RADIATIONS ♦ MECHANICS ♦ MOTION ♦ PHYSICAL PROPERTIES ♦ RADIATIONS ♦ STARS ♦ THERMODYNAMIC PROPERTIES ♦ VARIABLE STARS ♦ Astrophysics & Cosmology- Galaxies
Abstract We examine whether high-velocity clouds of neutral hydrogen (not the Magellanic Stream), observed in every longitude quadrant of the sky, can condense from a hot, dynamic corona above the plane of the Galaxy. Supernova-heated gas that arises above the disk must either flow outward as a wind or remain bound to the Galaxy in a dynamic corona in which gas is constantly in motion: a static corona is not stable. Since clouds cannot condense in a wind, we favor a corona and show that it is consistent with current values for the supernova heating rate above the disk. Gas continuously entering the corona from the disk rises up (in Z) and outward (in ..omega..) in an attempt to reach static equilibrium with the corona. The gas behaves adiabatically until radiative losses become important. Then, coronal gas is susceptible to thermal instabilities and neutral clouds condense from the corona. Clouds form toward the top of the corona at about one density scale height because thermal instabilities grow most rapidly there. After formation, clouds fall ballistically toward their point of origin.
Educational Use Research
Learning Resource Type Article
Publisher Date 1980-03-01
Publisher Department Astronomy Department, Columbia University
Publisher Place United States
Journal Astrophys. J.
Volume Number 236
Issue Number 2
Organization Astronomy Department, Columbia University


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