Bibcode
Crivellari, L.; Vladilo, G.; Beckman, J. E.; Foing, B. H.
Bibliographical reference
Astronomy and Astrophysics (ISSN 0004-6361), vol. 174, no. 1-2, March 1987, p. 127-138.
Advertised on:
3
1987
Citations
19
Refereed citations
16
Description
High-resolution spectra of Alpha Cen B, Xi Boo A, 70 Oph A, and Epsilon
Ind obtained using the Coude Echelle Spectrometer and the 1.4-m Coude
Auxiliary Telescope of ESO are analyzed. Variations in the normalized
fluxes for the four dwarfs are described. Position and intensity
measurements of the Ca II H features are examined. The use of the
spectra for chromospheric velocity field diagnostics is discussed. The
data reveal that it is possible to separate the effects of plages from
those due to vertical velocity fields; in some stars the H core samples
net upflow and in other net downflow; the layer sampled by the H3
feature shows a velocity close to that defined by the photospheric rest
frame; and the H2V/H2R asymmetry is useful as a linear measure of the
chromospheric vertical velocity gradient.