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Astron. Astrophys. 327, 173-182

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HS 1804 + 6753: a new eclipsing CV above the period gap*

H. Fiedler, H. Barwig, and K.H. Mantel

Universitäts-Sternwarte, Scheinerstr. 1, D-81679 München, Germany

Received 1 November 1996 / Accepted 18 April 1997


We present spectroscopic and photometric observations of the cataclysmic variable HS 1804 + 6753, a new eclipsing dwarf nova of the U Gem class. Its apparent visual brightness in quiescence is MV 14m. During its frequent outbursts the brightness increases by 1m - 2.3m. From our photometric data, we determined the orbital period to be FORMULA. The spectroscopic observations show the spectral lines of both stellar components. In quiescence, emission lines of H I, He I, He II, C II, and C III, as well as absorption lines of Fe I, Fe II, Ti II, and O I moving in phase with the primary are visible. During an outburst, additional emission lines of N II, N III, He II, and C III appear. The motion of the secondary can only be derived from a few Ca I absorption lines. The orbital inclination of the system is determined to be FORMULA. From radial velocities of both components, the respective masses are calculated, yielding FORMULA and FORMULA. The mass ratio derived from photometric data confirms the spectroscopic results. The radii of the two components are calculated to be FORMULA and FORMULA. Several outbursts have been observed so far indicating a relatively high repetition rate.

Key words: stars: binaries: eclipsing - stars: individual: HS 1804 + 6753 - stars: novae, cataclysmic variables

*Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, Spain, and at Wendelstein Observatory, Germany.

Send offprint requests to: H. Fiedler

© European Southern Observatory (ESO) 1997

Online publication: October 1, 1997
Last change: April 8, 1998