The census of cataclysmic variables in the ROSAT Bright Survey^*

¹ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
² Max-Planck Institut für extraterrestrische Physik, Giessenbachstrasse, 85740 Garching, Germany
³ South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape Town, RSA
⁴ SRON, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
⁵ SAO RAS, Nizhnij Arkhyz, Zelenchukskaya, Karachaevo-Cherkesia, Russia, 357147
⁶ Universitäts-Sternwarte Göttingen, Geismarlandstr. 11, 37083 Göttingen, Germany

Corresponding author: A. D. Schwope, aschwope@aip.de

Received: 7 August 2002
Accepted: 19 September 2002

Abstract

We give an identification summary and results of polarimetric, photometric and spectroscopic follow-up observations of new, X-ray bright cataclysmic variables. These were identified as optical counterparts of high galactic latitude sources in the ROSAT All-Sky Survey. This optical identification programme is termed the ROSAT Bright Survey (RBS) and represents the first complete soft X-ray selected, flux-limited sample of CVs at high galactic latitude (survey area ∼20400 sq.deg.). The systems described here escaped previous identification programmes since these surveys were designed to identify even brighter than ours or particularly soft X-ray sources. Among the 11 new RBS-CVs we find 6 magnetic systems of AM Herculis type, 4 dwarf novae (among them one candidate), and one particularly bright system of uncertain nature, tentatively identified as dwarf nova or symbiotic binary. Orbital periods could be determined for all magnetic systems which range from 87.1 min to 187.7 min. Three of the new dwarf novae have moderate to high inclination and two of them might be eclipsing. Using non-magnetic systems only we derive a space density of CVs of  pc^-3. This limit rests on the two new nearby, low-luminosity systems RBS0490 and RBS1955, with estimated distances of 30 pc only and luminosities below 10³⁰ erg s^-1.