The AM Herculis type binary E1405-451

Abstract

The authors report photometry and polarimetry of the AM Her-type binary E1405-451. For the first time circular polarization has been detected in such an object at wavelengths longer than 1 μm. The light curves and polarization curves at J and H show a minimum centred on the optical minimum but very much narrower. At H significant polarization is only observed for a short period on either side of the minimum. The observations are in good agreement with the predictions of cyclotron models. The form of the polarization curve indicates that the accretion column is always in the hemisphere of the white dwarf towards us, and that the field becomes almost parallel to the line-of-sight at the phase of the minimum.