Short-term brightness variations of V747 Cyg |
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| Institution: | 1. National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, Arizona 85719 USA;2. INAF, Osservatorio Astronomico di Torino, Via Osservatorio, 20, 10025 Pino Torinese TO, Italy;3. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Rd, 200030 Shanghai, China;1. The interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna and University Vienna, Veterinaerplatz 1, 1210, Vienna, Austria;2. Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Saiwai-cho 3-8-5, Fuchu, Tokyo, 183-8509, Japan;3. Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria;4. Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria;5. Christian Doppler Laboratory for the Development of Allergen Chips, Medical University Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria;6. Laboratory of Comparative Animal Medicine Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology Division of Animal Life Science, Institute of Agriculture, Saiwai-cho 3-8-5, 183-8509, Fuchu, Tokyo, Japan;7. Laboratory of Veterinary Molecular Pathology and Therapeutics, Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology, Saiwai-cho 3-8-5, 183-8509, Fuchu, Tokyo, Japan |
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| Abstract: | We have conducted high-speed photometric observations of the suspected cataclysmic variable V747 Cyg. The literature data about the spectra of this star are conflicting. Zwitter and Munari A&AS 107 (1994) 503] obtained spectroscopic observations which confirmed the cataclysmic variable nature of V747 Cyg, whereas Downes et al. AJ 110 (1995) 1824] have concluded that this object may be a Be + M binary rather than a cataclysmic variable. Our observations revealed the complete absence of the rapid flickering in this star at a millimagnitude level. This phenomenon is to be inherent in all cataclysmic variables. Instead, the lightcurves of V747 Cyg showed probably periodic smooth low-amplitude variations that were visible during each observational night. When V747 Cyg was observed in two colours simultaneously, these variations had the equal phases and amplitudes. A periodogram analysis revealed probable periods of 5.77, 7.41 and 7.59 h. These periods and the amplitude as well as the oscillation behaviour in the different colours are typical of variable Be stars. Hence, V747 Cyg may be a variable Be star but not a cataclysmic variable. |
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