Magnetic white dwarfs in the two micron all sky survey: a search for candidate binary systems.
WELLHOUSE J.W., HOARD D.W., HOWELL S.B., WACHTER S. and ESIN A.A.
Abstract (from CDS):
Our understanding of the formation and evolution of magnetic cataclysmic variables from initially detached, post-common-envelope binary stars containing a magnetic white dwarf and a main-sequence star is currently poorly constrained, due to the lack of observational identification of the progenitor systems. Very few potential pre-cataclysmic variables containing a magnetic white dwarf are known, compared with ~25% of the cataclysmic variable population that contain magnetic white dwarfs. We present the results of a search for candidate binary systems containing a magnetic white dwarf, which utilized photometric data from the Two Micron All Sky Survey (2MASS; as well as Hubble Space Telescope and WIYN Observatory follow-up data for several objects). Our target sample was drawn primarily from the comprehensive list of magnetic white dwarfs by Wickramasinghe & Ferrario, plus several recently identified objects selected from the literature. Out of 51 2MASS detections, no convincing binary candidates were found. However, six objects merit additional observation to determine the origin of a small near-infrared excess that could be attributed to a very low mass stellar or substellar companion. An additional four white dwarfs are possibly at the centers of previously unknown, and likely unresolved, planetary nebulae.
Stars: Binaries: Close - Infrared: Stars - magnetic fields - Stars: White Dwarfs