Abstract Magnetic cataclysmic variables (CVs) contain a white dwarf (WD) with a magnetic field strong enough to control the accretion flow from a late type secondary. In this paper, we identify a magnetic CV (CXOGSG J215544.4+380116) from the Chandra archive data. The X-ray light curves show a significant period of 14.1 ks, and the X-ray spectra can be described by a multi-temperature hot thermal plasma, suggesting the source is a magnetic CV. The broad dip in the X-ray light curve is due to the eclipse of the primary magnetic pole, and the additional dip in the bright phase of the soft and medium bands may be caused by the accretion stream crossing our line of sight to the primary pole. Follow-up optical spectra show features of an M2–M4 dwarf dominating the red band and a WD which is responsible for the weak upturn in the blue band. The mass (∼ 0.4 M⊙) and radius (∼ 0.4 R⊙) for the M dwarf are obtained using CV evolution models and empirical relations between the orbital period and the mass/radius. The estimated low X-ray luminosity and accretion rate may suggest the source is a low-accretion-rate polar. In addition, Very Large Array observations reveal a possible radio counterpart to the X-ray source, but with a low significance. Further radio observations with high quality are needed to confirm the radio counterpart and explore the properties of this binary system.
Keywords novae, cataclysmic variables — stars: late-type — stars: magnetic field
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