Bibcode
Garcia Lopez, R. J.; Rebolo, R.; Beckman, J. E.; McKeith, C. D.
Bibliographical reference
(IAU, European Regional Astronomy Meeting on New Windows to the Universe, 11th, La Laguna, Spain, July 3-8, 1989) Astrophysics and Space Science (ISSN 0004-640X), vol. 169, no. 1-2, July 1990, p. 67-75.
Advertised on:
7
1990
Citations
0
Refereed citations
0
Description
The first results of a study of F-type MS stars using the He I D3
absorption feature at 5876 A as an indicator of stellar activity and
structure are presented. The observations were obtained with the QUB
echelle spectrograph at the Cassegrain focus of the 4.2 m William
Herschel telescope. Seventeen F-stars of the Hyades main sequency were
chosen as a first sample. It was found that He I D3 and X-ray emission
appear around B - V = 0.3, indicating the onset of sub-surface
convection zones. Below this value, in stars with B - V not greater than
0.42-0.44 the behavior of the He I D3 equivalent width against Rossby
number is different from that observed in later type stars, indicating
that the presence of nonradiative mechanisms other than dynamo must be
important in heating the chromospheres of these hotter stars.