Astronomers from the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany have discovered a new magnetic cataclysmic variable system, likely of the polar type. This discovery was made possible by analyzing data from the European Space Agency’s XMM-Newton and Gaia satellites.
Cataclysmic variables (CVs) are binary star systems consisting of a white dwarf and a normal star companion. They are known for their irregular brightness, which can increase significantly before returning to a quiescent state. Polars, a subclass of CVs, are distinguished by the presence of a very strong magnetic field in their white dwarfs.
The team, led by AIP’s Samet Ok, identified the new cataclysmic variable, designated as XMM J152737.4-205305.9 (or XMM 152737 for short). This identification was made by correlating the CV candidate catalog released by Gaia Data Release 3 (DR3) with the XMM-Newton archive.
XMM 152737 exhibits a singular period that aligns with the synchronous rotation characteristic observed in polars. The system displays harmonics in its power spectrum and has a relatively short orbital period, traits commonly observed in known polars.
The source showcases two distinct dips that exhibit a recurring pattern with a precise period of approximately 112.4 minutes. These dips may be caused by an eclipse of the white dwarf by the donor star or an obscuration of the accretion region on the white dwarf by the accretion stream.
Observations show that XMM 152737 has prominent emission lines corresponding to hydrogen and helium, strongly suggesting that the object is a polar-type cataclysmic variable.
Located some 3,770 light years away from Earth, XMM 152737’s X-ray luminosity is estimated to be between 30 and 60 nonillion erg/s. Assuming that the system is eclipsing, the white dwarf and the secondary star are calculated to have masses of 0.8 and 0.14 solar masses, respectively.
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