VV Puppis and AN Ursae Majoris: a radial velocity study.

The observations of the emission lines of VV Puppis and AN Ursae Majoris show spectacular line variations in VV Puppis with a mean radial velocity amplitude of 376 km/s and clearly defined broad and sharp components. The AN UMa has similar, but less spectacular variations; the mean radial velocity of 256 km/s and the base and emission lines are 49 deg out of phase. Integration of particle trajectories in the Roche geometry where a dipole magnetic field dominates the gas flow confirms that gas is threaded on the magnetic field near the L(1) point from which it free-falls onto the favorably oriented magnetic pole of the white dwarf.