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Rotational modulation and flares on RS CVn and BY Dra stars. VI - Physical parameters of the chromospheres/transition regions of V 711 Tau (HR 1099), II Peg and AR Lac during October 1981Ground-based optical and IUE satellite-ultraviolet observations of three RS CVn stars are combined with density sensitive line ratios and differential emission measure curves to describe the physical conditions in their outer atmospheres. Solar-like densities are found to be representative of average conditions on two of the stars, V 711 Tau and AR Lac. The total radiative losses from these two stars are estimated and found to be larger than the sun by at least two orders of magnitude. Consideration of the volume emitting in two of the principal transition region lines suggests a possible relation between the disk 'filling factor' for these two lines and the dynamo-related Rossby number. Only one hemisphere of the star II Peg, the one showing least evidence of starspots, is similar. On the opposite hemisphere the presence of a discrete emitting region is deduced which is almost coincident in phase with the passage of the dominant optical spot group across the visible disk. The dimensions of this region, and an illustrative interpretation in terms of a large emitting magnetic loop, are discussed. It is compared to large active region loops on the sun.
Document ID
19870063426
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Byrne, P. B.
(Armagh Observatory Ireland)
Doyle, J. G.
(Armagh Observatory United Kingdom)
Brown, A.
(Joint Institute for Laboratory Astrophysics Boulder, CO, United States)
Linsky, J. L.
(Joint Institute for Laboratory Astrophysics; NBS, Quantum Physics Div., Boulder CO, United States)
Rodono, M.
(Osservatorio Astrofisico; Catania, Universita Italy)
Date Acquired
August 13, 2013
Publication Date
June 1, 1987
Publication Information
Publication: Astronomy and Astrophysics
Volume: 180
Issue: 1-2
ISSN: 0004-6361
Subject Category
Astrophysics
Accession Number
87A50700
Funding Number(s)
CONTRACT_GRANT: NAG5-82
Distribution Limits
Public
Copyright
Other

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