Identification of the soft X-ray source WGA J1802.1+1804 with a new magnetic cataclysmic variable

Abstract

We have discovered a bright (V~14.5) cataclysmic variable during observations of the soft X-ray sources in the list of Singh et al. The optical source, which is coincident with the X-ray position of WGA J1802.1+1804, shows all the characteristics of a magnetic AM Herculis-type system: circular polarization, He II strength greater than Hβ, multiple line components, and a consistent photometric, polarimetric, spectroscopic, and X-ray period of 113 minutes. The X-ray spectrum shows a dominant soft blackbody (kT=20-45 eV) and a weaker bremsstrahlung component (kT>1 keV), while the circular polarization is relatively low (4% in the red).