Polars: Evidence for magnetically confined emission
€To achieve large levels of circular polarisation,
radiation process must be largely cyclotron
emission
€For emission to be in the optical,
require high values of magnetic field strength, ~30 MGauss (~3000 Tesla)
€Expect this to disrupt the disk
€Eclipse lightcurves show very sharp (seconds) drops and rises in brightness, consistent with a small spot on the white dwarf
€Evidence for magnetically controlled accretion regions
HU
Aqr
Bridge et al (2002)