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Spectroscopy and photometry of the interacting binary CX Draconis - evidence for circumstellar matter

An analysis of an extensive collection of spectroscopic and photometric observations of the interacting binary CX Dra led to the following main conclusions: 1. Both, spectroscopy and photometry indicate that the circumstellar environment changes in cycles of a few hundred days. The length of the cycles is variable. 2. The long-term H-alpha emission and light changes of CX Dra have a very similar character. This may mean a common cause which drives both spectroscopic and photometric long-term variations of the star. 3. The equivalent width of the H-alpha difference profiles and the light of CX Dra are modulated with the orbital period of 6d696. The corresponding phase diagrams indicate a great deal of scatter, but the modulation is quite conspicuous when long data strings are used. The pattern of the phase diagram constructed for H-alpha difference profiles suggests a permanent presence of the emission. 4. The radial velocities of the H-alpha emission peak follow a S-wave pattern. The resulting velocity (Doppler) map shows that the source of the single-peaked emission lies close to the L_1 point near the secondary star.

emission-line stars; spectroscopic Be-binaries; CX Dra

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