FOLLOW-UP OBSERVATIONS OF THE REMARKABLE DOUBLE-DEGENERATE BINARY LB-11146

LB 11146 is a double-degenerate binary system consisting of two white dwarfs of very similar mass and surface temperature, but widely differ ent magnetic field strengths. In an attempt to constrain the possible evolutionary tracks of the object, time series Halpha spectroscopy of the DA component was obtained with a time resolution as high as 11.5 m in and total base line of 16 days. Cross-correlation analysis reveals no evidence of variation to a limit of K less than or similar to 20 km s-1 on periods of approximately 1 hr, effectively ruling out the poss ibility of future orbit decay by gravitational radiation to a Type I s upernova. However, both single-star and binary modes of past evolution are still viable. In addition, red spectroscopy was obtained to searc h for the highly displaced 2p0 to 3d-1 absorption component of Halpha from the magnetic star, which is strong and nearly stationary at appro ximately 8500-8532 angstrom in fields of 350-1200 MG. The detection of a deep feature near this location coupled with an identification of a displaced component of Ly alpha in the IUE spectrum of the object con firm that hydrogen is present in the atmosphere of the magnetic compon ent. Spectral modeling suggests a polar strength of approximately 670 MG (for dipolar geometry), but no model obtains a completely satisfact ory fit, and at least one additional atmospheric constituent (neutral helium?) is required. Based on these conclusions, the magnetic compone nt is reclassified as DAXP.