RX J1914.4+2456: the first double-degenerate polar?

RX J1914.4+2456 exhibits a light curve with a strong modulation at 569 s: this period is characteristic of the white dwarf spin period in intermediate polar (IP) systems. However, the X‐ray light curve is difficult to reconcile with current models for IP emission. We argue that a simpler explanation is that the system is a polar with a degenerate secondary star, which would make it the first known system of its kind. As such it should contain the first example of an He‐dominated radial accretion flow on to the white dwarf surface, and RX J1914.4+2456 would have the shortest known orbital period of any binary system.