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Astron. Astrophys. 364, L85-L88 (2000)

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Letter to the Editor

Properties and nature of Be stars

XX. Binary nature and orbital elements of [FORMULA] Cas

P. Harmanec 1,2, P. Habuda 3, S. tefl 2, P. Hadrava 2, D. Koráková 4,2, P. Koubský 2, J. Krtika 4,2, J. Kubát 2, P. koda 2, M. lechta 2 and M. Wolf 1

1 Astronomical Institute of the Charles University, V Hole ovi kách 2, 180 00 Praha 8, Czech Republic
2 Astronomical Institute of the Academy of Sciences, 251 65 Ond ejov, Czech Republic
3 Faculty of Mathematics and Physics of the Charles University, Ke Karlovu 3, 121 16 Praha 2, Czech Republic
4 Masaryk University, Faculty of Science, Department of Theoretical Physics and Astrophysics, 611 37 Brno, Czech Republic

Received 20 September 2000 / Accepted 27 November 2000


An analysis of accurate radial velocities (RVs) of the Be star [FORMULA] Cas from 295 Reticon spectrograms secured between October 1993 and May 2000 allowed us to prewhiten the RVs for the long-term changes and to obtain the first orbital RV curve of this star. The orbital period is 203[FORMULA]59 and the orbit has an eccentricity of 0.26. The orbital motion is de- tectable even in the published velocities, based on photographic spectra. This implies that [FORMULA] Cas is a primary component of a spectroscopic binary. The secondary has a mass of about 1 [FORMULA], appropriate for a white dwarf or a neutron star, but it could also be a normal late-type dwarf. The ultimate solution of the dispute whether the observed X-ray emission is associated with the secondary or with the primary will need further dedicated studies.

Key words: stars: binaries: spectroscopic – stars: emission-line, Be – stars: individual: fl Cas

Send offprint requests to: P. Harmanec (hec@sunstel.asu.cas.cz)

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001