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Polarized Emission and the Discovery of New Magnetic CVs

Published online by Cambridge University Press:  12 April 2016

Gary D. Schmidt
Gary D. Schmidt*
Affiliation:
Steward Observatory, The University of Arizona, Tucson, AZ 85721 , USA

Abstract

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Recent quasar surveys have identified several new magnetic cataclysmic variables accreting at remarkably low rates, ~10−13M⊙ yr−1. The new discoveries raise questions regarding selection effects that may influence the current sample and the traditional evolutionary conclusions that have been drawn. This paper reviews the techniques that have been used to identify polars, including a summary of the optical polarization as a function of accretion rate and magnetic field strength. The new, low-ṁ systems accrete without a shock and cooling is dominated by optical cyclotron emission in very well-defined harmonics. These binaries, which have been found to accrete at far below the rate corresponding to angular momentum loss by gravitational radiation, also appear to contain unusually cool white dwarfs, suggesting that they are either at an advanced age or in unusual evolutionary states.

Type
Part 1. Population and Evolution
Information
International Astronomical Union Colloquium , Volume 190: Magnetic Cataclysmic Variables , 2004 , pp. 22 - 32
Copyright
Copyright © Astronomical Society of the Pacific 2004

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