Following the suggestion of Schwope et al that the magnetic cataclysmic variable RX J2115–5840 maybe a near-synchronous polar , we obtained optical polarimetry of this system over a 2 week period .
From a power spectrum of the circular polarimetry data we determine that the spin period of the white dwarf and the binary orbital period which differ by 1.2 percent .
RX J2115–5840 is thus the fourth near synchronous polar and has the shortest spin-orbit beat period : 6.3 days .
By folding the data on spin , beat and orbital periods we find evidence that the accretion stream is directed towards opposite magnetic poles as the stream precesses around the white dwarf on the spin-orbit beat period .
The phasing requires that the accretion flow must be directed onto the same magnetic field line at all spin-orbit beat phases implying that at some phases the flow must follow a path around the white dwarf before accreting .
This is difficult to reconcile with simple views of how the accretion stream attaches onto the magnetic field of the white dwarf .