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A Far-Ultraviolet Study of the Cygnus Loop Using the VOYAGER Ultraviolet SpectrometersWe have used the Voyager 1 and 2 Ultraviolet Spectrometers to study the far-ultraviolet emissions from different types of shock waves in the Cygnus Loop. In the southeast and northern parts of the supernova remnant (SNR), we have measured the O(VI) lambda1035 surface brightness from the main blast wave. This value is several times below the average and more than one order of magnitude below the peak O(VI) brightness in the SNR as measured with Voyager. A simple blast wave model appears able to reproduce the observations in the southeast and the northern parts of the Cygnus Loop but can only account for 10%-15% of the total O(VI) emission from the Cygnus Loop. The brightest O(VI) and C(III) lambda977 emission is found coincident with optical filamentation and X-ray enhancements in the northeast. We interpret the observations in the northeast in terms of nonradiative and incomplete shocks whose surface area rises in the optical filamentary regions. We conclude that the bulk of the O(VI) emission from the Cygnus Loop arises from optically bright clouds within which intermediate-velocity (200 + 50 km/s) nonradiative and incomplete shocks are widespread.
Document ID
19970011956
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Vancura, Olaf
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA United States)
Blair, William P.
(Johns Hopkins Univ. Baltimore, MD United States)
Long, Knox S.
(Johns Hopkins Univ. Baltimore, MD United States)
Raymond, John C.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA United States)
Holberg, J. B.
(Arizona Univ. Tucson, AZ United States)
Date Acquired
August 17, 2013
Publication Date
November 10, 1993
Publication Information
Publication: The Astrophysical Journal
Publisher: American Astronomical Society
Volume: 417
Subject Category
Astronomy
Report/Patent Number
NAS 1.26:203231
NASA-CR-203231
Accession Number
97N70878
Funding Number(s)
CONTRACT_GRANT: NAG5-988
CONTRACT_GRANT: NAG5-1276
CONTRACT_GRANT: NAG5-528
Distribution Limits
Public
Copyright
Public Use Permitted.
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