An optical and near-infrared study of the AM Herculis-type binary CW 1103+254

All main components of the AM Herculis-type binary CW 1103 + 254 can be distinguished by means of observations encompassing optical and near-IR photometry and polarimetry, together with optical spectroscopy and spectropolarimetry. The M-dwarf secondary's IR magnitude is used to estimate the distance of the system as 136 pc. Observed emission line profiles can be understood in terms of two components, one of which originates in the white dwarf's infalling stream of material while the other comes from the vicinity of the secondary. The excess radiation noted during the bright phase can be understood as cyclotron radiation from the shock-heated region near the white dwarf magnetic pole. Changes that occurred in the system in 1982 and 1983 indicate precessional motion of either the white dwarf rotation or the magnetic axis.