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Astron. Astrophys. 325, 601-608 (1997)

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Spectroscopy of the dwarf nova CG Draconis

Albert Bruch , Thomas Schimpke * and Alexander Kochsiek

Astronomisches Institut, Westfälische Wilhelms-Universität, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany

Received 27 January 1997 / Accepted 27 March 1997


We present spectroscopic observations of the dwarf nova CG Dra which exhibits a two component spectrum. Absorption lines stand out clearly and can be classified as belonging to spectral type K5  [FORMULA]  2. The wavelength dependent veiling fraction could be determined. The emission spectrum is not untypical for a dwarf nova but shows some peculiarities in the helium lines. Radial velocity measurements indicate a period of either [FORMULA] or [FORMULA], too short for the absorption line spectrum if interpreted within the canonical CV model. Worse, the absorption line radial velocity amplitude is approximately a factor 30 less than that for the Balmer lines and in phase with them. This cannot easily be explained in the framework of standard CV models. However, it cannot be excluded that the RV variations of the absorption lines are accidential and that the corresponding star is not a component of the cataclysmic variable.

Key words: stars: binaries: close – stars: novae, cataclysmic variables – stars: individual: CG Dra

* Visiting Astronomer, German-Spanish Astronomical Centre, Calar Alto, operated by the Max-Planck-Institut für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy

Send offprint requests to: Albert Bruch

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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998