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Orbit crowding of molecular gas at a bar-spiral arm transition zone in M83The southwestern bar-spiral arm transition zone in M83 is been studied in CO, H-alpha, H I, red light, and the radio continuum. A massive molecular gas complex in the heart of the transition zone is composed or two principal components which have the morphology and kinematics expected from orbit crowding, where gas on highly elliptical orbits form the bar region converges with gas on more circular orbits from the spiral arm region. Three mechanisms for the origin of the orbit crowding are investigated, and it is proposed that the crowding is due primarily to density wave streaming motions caused by the bar and spiral arms. The inner CO component is partially coincident with a region of highly polarized radio continuum emission which precedes the H-alpha spiral arm by 15-25 arcsec, indicating that it lies on or just downstream from a shock front. This suggests that the bar gas approaching the transition zone is shocked and explains the ridge of dense gas seen upstream from the spiral arm.
Document ID
19920030038
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kenney, Jeffrey D. P.
(California Institute of Technology Pasadena, United States)
Lord, Steven D.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 15, 2013
Publication Date
November 1, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 381
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
92A12662
Funding Number(s)
CONTRACT_GRANT: NSF AST-87-14405
Distribution Limits
Public
Copyright
Other

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