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Rotation and emission lines in stars and accretion disksIn the accretion disks of quiescent dwarf novae, Doppler mapping studies reveal that Balmer emission lines increase sharply toward the center of the disk, with surface brightnesses scaling roughly as R exp -3/2 varies as Omega(Kep). Similarly, among chromospherically active stars the H-alpha and Ca II H and K emission cores are stronger in the more rapidly rotating stars, with surface brightnesses scaling again roughly as Omega(rot). Since in both cases the emission lines scale linearly with the rotation frequency, it is proposed that the mechanism powering the emission lines in quiescent accretion disks is the same as that in chromospherically active stars, namely, the emergence of magnetic flux generated by the action of a dynamo, and its interaction with the atmosphere. If this empirical connection between disks and stars is in fact due to magnetic dynamos, the range of rotation rates available for testing dynamo theories expands from a factor of 1000 to 10 to the 7th.
Document ID
19910056293
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Horne, Keith
(Space Telescope Science Institute Baltimore, MD, United States)
Saar, Steven H.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Date Acquired
August 15, 2013
Publication Date
June 20, 1991
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 374
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A40916
Funding Number(s)
CONTRACT_GRANT: NAGW-2264
CONTRACT_GRANT: NAGW-112
CONTRACT_GRANT: NAGW-1796
Distribution Limits
Public
Copyright
Other

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