Astron. Astrophys. 358, 600-604 (2000)

A newly-discovered cataclysmic binary near the ROSAT galactic plane source RX J1910.8+2856

J.R. Thorstensen ¹ and F. Haberl <sup>2

1</sup> Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755-3528, USA
² Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany

Received 21 December 1999 / Accepted 23 February 2000

Abstract

We report the discovery of a new cataclysmic binary star from the ROSAT Galactic Plane Survey. The star has at minimum light and we have measured it as bright as . Spectroscopy shows broad hydrogen and helium emission lines; HeII is not detected. H radial velocities yield an orbital period of d ( h). Time-series photometry covering one orbital cycle near maximum light shows irregular variability, but no evidence of an eclipse. The system appears to be a new dwarf nova of the U Gem or Z Cam type, and is unlikely to be a magnetic system. Its period is unusually short for a U Gem star.

Curiously, the new cataclysmic binary is 83" from the original ROSAT PSPC survey position, which puts it outside the PSPC positional uncertainty. Follow-up observations with the HRI reveal that the PSPC source is the superposition of two sources, and the cataclysmic is much the weaker of the two in X-rays. Its discovery in this survey is therefore essentially accidental. A mag star is located 1.2" from the stronger source's HRI position.

Key words: stars: binaries: close stars: individual: RX J1910.8+2856 stars: individual: RX J191059.6+285639 stars: novae, cataclysmic variables X-rays: stars

Send offprint requests to: J.R. Thorstensen (thorstensen@dartmouth.edu)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Identification
  • 2.1. Optical
  • 2.2. X-ray
• 3. Photometry
• 4. Spectroscopy
• 5. HRI observations
• 6. Discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: June 8, 2000
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