Photometry and polarimetry of AM Herculis in its faint state

Abstract

Infrared and optical photometry and polarimetry of AM Herculis during the faint state of its long-term light variations are presented. The contributions of the two stellar photospheres are estimated and the distance of the system derived. The observations show very little polarized cyclotron radiation in the optical, but still show substantial polarization in the near-infrared. The cyclotron flux has dropped by a factor of about 12 from the normal bright state. The change in the cyclotron spectrum can be understood if the column density of electrons in the emitting region has dropped by a factor of about 103 with the area and temperature remaining the same.