A Broad Observational Study of the Eclipsing Magnetic Cataclysmic Variable RE 2107-05

We have carried out extensive observations of the bright eclipsing cataclysmic variable RE 2107-05 using CCD and high-speed photelectric photometry, low- and moderate-resolution phase-resolved optical spectroscopy, broad-band linear and circular polarimetry, and optical spectropolarimetry. We confirm that the system is a synchronized magnetic variable of the AM Herculis type, with a spin/orbit period of 125.02 minutes. Both broad and narrow components are detected in the emission-line spectrum, with radial velocities phased appropriately for their origin in the accretion stream and irradiated secondary star, respectively. In addition to the normal series of Balmer and helium lines, Fe II emission from the funnel is conspicuous. RE 2107-05 provides new insight into the flow of accreting gas in an AM Her system. At certain phases, the broad component of H-alpha splinters into multiple components suggesting individual coherent streamlines. Eclipse of the accretion funnel by the secondary star is evident in protracted ingress and egress components, displaced approximately 15 deg in longitude from the spot. These transitions show remarkable differences in character from one eclipse to the next, signifying substantial changes in the magnetospheric interaction on an orbital timescale.