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Transition region fluxes in A-F Dwarfs: Basal fluxes and dynamo activityThe transition region spectra of 87 late A and early F dwarfs and subgiants were analyzed. The emission line fluxes are uniformly strong in the early F stars, and drop off rapidly among the late A stars. The basal flux level in the F stars is consistent with an extrapolation of that observed among the G stars, while the magnetic component displays the same flux-flux relations seen among solar-like stars. Despite the steep decrease in transition region emission flux for B-V less than 0.28, C II emission is detected in alpha Aql (B-V = 0.22). The dropoff in emission is inconsistent with models of the mechanically generated acoustic flux available. It is concluded that, although the nonmagnetic basal heating is an increasingly important source of atmospheric heating among the early F stars, magnetic heating occurs in any star which has a sufficiently thick convective zone to generate acoustic heating.
Document ID
19890001376
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Walter, Frederick M.
(Colorado Univ. Boulder., United States)
Schrijver, Carolus J.
(Joint Inst. for Lab. Astrophysics Boulder, Colo., United States)
Boyd, William
(Colorado Univ. Boulder, CO, United States)
Date Acquired
September 5, 2013
Publication Date
June 1, 1988
Publication Information
Publication: ESA, A Decade of UV Astronomy with the IUE Satellite, Volume 1
Subject Category
Astronomy
Accession Number
89N10747
Funding Number(s)
CONTRACT_GRANT: NAG5-429
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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