H emission in the chromospherically active binary o2 Coronae Borealis (TZ CrB)
A. Frasca 1,
S. Catalano 2 and
D. Mantovani 1, 3
Received 2 July 1996 / Accepted 10 September 1996
Spectrophotometry of the chromospherically active system Coronae Borealis was obtained in the H region, during two observing campaigns at Catania Observatory. During the first campaign, 1988 June 22 - 29, 135 spectra were collected, while 12 spectra were obtained during the second campaign which spanned from June to June 1989.
We have recorded the spectra of the two stars composing the visual binary ( and CrB) on the same frame by placing the spectrograph slit along the line connecting the two stars. This enabled us to obtain a light curve in the red band ( 6410 - 6590 Å), using CrB as comparison star. The light curve exhibits changes in the amplitude and in the phase of minimum light between the two observing seasons. The equivalent width of the H emission core has been evaluated using the spectrum synthesis method. H emission from both components of the inner system is detected in the spectra near quadrature, but it is stronger in the cooler G0 V star. The H equivalent width shows low-amplitude modulation in both years which seems to be anti-correlated with the simultaneous light curve.
Comparing our results of the 1988 campaign with the contemporaneous X-ray, UV, and Radio measurements reported by Stern et al. (1992) we show that the Mg II flux of the cooler component is anti-correlated with our light curve, and a similar behaviour is displayed by the Ly- flux reported by Hannikainen et al. (1990).
Key words: stars: chromospheres stars: activity stars: binaries: close object: oe2 CrB; TZ CrB
Send offprint requests to: S. Catalano
© European Southern Observatory (ESO) 1997
Online publication: July 3, 1998