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

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

Abstract

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 . During its frequent outbursts the brightness increases by . From our photometric data, we determined the orbital period to be . 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 . From radial velocities of both components, the respective masses are calculated, yielding and . The mass ratio derived from photometric data confirms the spectroscopic results. The radii of the two components are calculated to be and . 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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Contents

• 1. Introduction
• 2. Observation and data reduction
  • 2.1. Spectroscopy
  • 2.2. Photometry
• 3. Data analysis
  • 3.1. Photometry
    • 3.1.1. Period analysis
    • 3.1.2. Eclipse times
    • 3.1.3. Photometric mass ratio
  • 3.2. Spectroscopy
    • 3.2.1. Radial velocity of the white dwarf
    • 3.2.2. Radial velocity of the secondary
    • 3.2.3. System velocity
• 4. Determination of system parameters
  • 4.1. Functional context
  • 4.2. Calculation of the parameters
• 5. Discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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