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Ca II H High-Resolution Spectral Monitoring of Active Late-type Dwarfs

Published online by Cambridge University Press:  12 April 2016

J. E. Beckman ,
R. J.García López ,
R. Rebolo  and
L. Crivellari
J. E. Beckman
Affiliation:
Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
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
L. Crivellari
Affiliation:
Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste, Italy

Abstract

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We have monitored Ca II H with a spectral resolution of 8 × 104, in asimple 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
Part IV Stellar activity
Information
International Astronomical Union Colloquium , Volume 130: The Sun and Cool Stars: activity, magnetism, dynamos , 1991 , pp. 463 - 465
Copyright
Copyright © Springer-Verlag 1991

References

Crivellari, L., Beckman, J.E., Foing, B.H., Vladilo, G.: 1987, Astron. Astrophys. 174, 127 Google Scholar
Rebolo, R., García López, R. J., Beckman, J.E., Vladilo, G., Foing, B.H., Crivellari, L.: 1989, Astron. Astrophys. Suppl. Ser. 80, 135 Google Scholar