Ca II H high-resolution spectral monitoring of active late-type dwarfs

Bibcode
1991LNP...380..463B
DOI
10.1007/3-540-53955-7_180
Beckman, J. E.; Garcia López, R. J.; Rebolo, R.; Crivellari, L.
Bibliographical reference

The Sun and Cool Stars. Activity, Magnetism, Dynamos. Proceedings of Colloquium No. 130 of the International Astronomical Union, held in Helsinki, Finland, July 17-20, 1990. Editors, I. Tuominen, D. Moss, G. Rudiger; Publisher, Springer-Verlag, Berlin, Germany; New York, NY, 1991. ISBN # 3-540-53955-7. LC # QB524 .I59 P.463, 1991

Advertised on:
0
1991
Number of authors
4
IAC number of authors
0
Citations
1
Refereed citations
1
Description
We have monitored Ca II H with a spectral resolution of 8 x 104, in a sample of late-type MS stars over a four-year period. The high resolution enables us to add information on velocity fields to the usual flux monitoring. We detect changes in wavelength of different parts of the Ca II H feature, which can be interpreted as velocity fields in the lower chromosphere, with downflow and upflow of order 0.5 km s-1, depending on the star. Flux variations in Ca II H emission can be ascribed, via velocity tagging, to long-term change in plage cover rather than short-term modulation by (incompletely sampled) rotation cycles.
Type
Refereed

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