Infrared photometry of the intermediate polar XY Arietis (H0253+193)

Near-infrared H-band photometry of the eclipsing intermediate polar XY Ari shows an ellipsoidal variation from the Roche-lobe-filling secondary star, and a marginally significant spin pulse. We model the light curve, finding that the mass ratio of the system lies in the range 0.43 < q < 0.71, and the system inclination in the range 80 degrees < i < 87 degrees. We show that IR-emitting material circles around the white dwarf, consistent with an accretion disc extending to more than 0.3 of the primary's Roche lobe. The H-band light of this material cannot be asymmetric about the white dwarf by more than a factor of 2.