The Discovery of a Persistent Quasi-Periodic Oscillation in the Intermediate Polar TX Col

We report on the detection of an ~5900 s quasi-periodic variation in the extensive photometry of TX Col spanning 12 years. We discuss five different models to explain this period. We favour a mechanism where the quasi-periodic variation results from the beating of the Keplerian frequency of the blobs' orbiting in the outer accretion disc with the spin frequency, and from modulated accretion of these blobs’ taking place in a shocked region near the disc/magnetosphere boundary.