A&A Supplement Series, Vol. 125, October II 1997, 263-287
Received October 14; accepted December 23, 1996
, Na I D1, D2,
and He I D3 observations
D. Montes - M.J. Fernández-Figueroa - E. De Castro - J. Sanz-Forcada
Send offprint request: D. Montes
Departamento de Astrofısica,
Facultad de Fısicas,
Universidad Complutense de Madrid, E-28040 Madrid, Spain
e-mail: dmg@ucmast.fis.ucm.es
This is the first paper of a series aimed at studying
the chromosphere of active binary systems
using the information provided for several optical spectroscopic
features.
Simultaneous H, Na I D1, D2,
and He I D3 spectroscopic observations are reported here
for 18 systems.
The chromospheric contribution in these lines have been determined
using the spectral subtraction technique.
Very broad wings have been found in the subtracted H profile
of some of the more active stars.
These profiles are well matched using a two-components
Gaussian fit (narrow and broad) and the broad component
could be interpreted as arising from microflaring.
Prominence-like extended material have been detected in a near-eclipse
H observation of the system AR Lac.
The excess emission found in the Na I D1 and D2 lines
by application of the spectral subtraction technique and the
behaviour of the H line in the corresponding simultaneous
observations indicate that the filling-in of the core of these lines
is a chromospheric activity indicator.
For giant stars of the sample
the He I D3 line has been detected in absorption
in the subtracted spectra.
An optical flare has been detected in UX Ari and II Peg through
the presence of the He I D3 in emission in coincidence with the
enhancement of the H emission.
keywords: stars: activity -- stars: binaries: close -- stars: chromospheres -- stars: flare -- stars: late-type