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He I 5876 Å Line in the Study of Chromospheric Activity in F-type MS Stars

Published online by Cambridge University Press:  12 April 2016

R. J. García López ,
R. Rebolo ,
J. E. Beckman  and
C. D. McKeith
R. J. García López
Affiliation:
Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
R. Rebolo
Affiliation:
Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
J. E. Beckman
Affiliation:
Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
C. D. McKeith
Affiliation:
Department of Pure and Applied Physics, The Queen’s University of Belfast, Belfast BT7 INN, Northern Ireland

Abstract

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We have measured the He I D3 line, λ5876 Å, in 32 F-type young open cluster stars and in 4 field stars. Combining our results with previous observations of D3 we strengthen the following conclusions: (a) Sub-surface convective zones appear, on the main sequence, around F0 (B – V ~ 0.3). (b) The stars between F0 and F5 (0.3 ≲ B – V ≲ 0.42) are chromospherically “active” irrespective of age, which implies a heating mechanism not affected by evolutionary effects. In this range the activity in D3 and X-rays are uncorrelated. (c) For stars later than F5 the correlation among all the activity indices, chromospheric and coronal, shows a common energy source. Convective zones here should be deep enough to generate magnetic fields capable of supplying this energy, and also for braking the rotation.

Information

Type
Part IV Stellar activity
Information
International Astronomical Union Colloquium , Volume 130: The Sun and Cool Stars: activity, magnetism, dynamos , 1991 , pp. 477 - 479
Copyright
Copyright © Springer-Verlag 1991

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