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The chromospheres of late-type stars. I - Eridani as a test case of multiline modellingA new model of the lower chromosphere of the dwarf K2 star Epsilon Eridani is derived by matching flux profiles of the Ca IR triplet lines 8498 and 8542 A H-alpha and H-beta lines and the Na D lines (all observed simultaneously at the AAT), and the Ca II K line. The coupled non-LTE equations of statistical equilibrium and radiative transfer are solved under the constraint of hydrostatic equilibrium using the Carlsson (1986) code. Within the framework of the model, the Na D lines are an important photospheric diagnostic, and the Ca IR triplet lines can be used to locate the temperature minimum. The computed H-alpha and H-beta depths are highly sensitive constraints on the transition zone gradients and base pressures allowing us to derive a pressure at the base of the transition zone of 0.9 dyn/cm.
Document ID
19910050708
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Thatcher, John D.
(Sydney, University Australia)
Robinson, Richard D.
(NASA Goddard Space Flight Center; Computer Sciences Corp. Greenbelt, MD, United States)
Rees, David E.
(CSIRO Div. of Radio Physics, Epping, Australia)
Date Acquired
August 15, 2013
Publication Date
May 1, 1991
Publication Information
Publication: Royal Astronomical Society, Monthly Notices
Volume: 250
ISSN: 0035-8711
Subject Category
Astrophysics
Accession Number
91A35331
Distribution Limits
Public
Copyright
Other

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