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Astron. Astrophys. 327, 173-182 (1997)

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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 [FORMULA]. During its frequent outbursts the brightness increases by [FORMULA]. 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

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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998