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Ultraviolet spectroscopy of the outer layers of starsUltraviolet observations of the extended atmospheres and circumstellar envelopes of early-type and cool stars are reviewed. UV spectra of OB stars have shown that mass loss occurs in virtually all these stars and in many Be stars, and the Copernicus satellite has also provided information on the physical conditions and variability of the winds. The winds have been interpreted in terms of hot coronal wind models, imperfect flow models and radiation pressure models, and estimates of mass loss ranging from 10 to the -10th to 9 x 10 to the -6th solar masses/year have been obtained. Further UV data of faint stars, additional wavelengths and time variability are required. Recent UV and X-ray experiments have detected stellar chromospheres, transition regions coronas and winds in cool stars. Semiempirical line-profile and line-flux models and purely theoretical atmospheric models have been constructed to explain chromosphere, corona and wind data, and future observations of the physical properties of stellar chromospheres, coronas and winds, terms in the energy balance equation, stellar activity and its long-term variability and atmospheric modifications due to the presence of companion stars are proposed for such missions as Spacelab.
Document ID
19800038726
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Snow, T. P., Jr.
(Colorado, University Boulder, Colo., United States)
Linsky, J. L.
(Joint Institute for Laboratory Astrophysics; National Bureau of Standards, Quantum Physics Div., Boulder Colo., United States)
Date Acquired
September 4, 2013
Publication Date
February 1, 1980
Publication Information
Publication: Astrophysics and Space Science
Volume: 67
Issue: 2, Fe
Subject Category
Astronomy
Report/Patent Number
PB80-216997
Accession Number
80A22896
Funding Number(s)
CONTRACT_GRANT: NAS5-23274
CONTRACT_GRANT: NGR-06-003-057
Distribution Limits
Public
Copyright
Other

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