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W UMa Binaries

Published online by Cambridge University Press:  07 August 2017

O. Vilhu
O. Vilhu*
Affiliation:
Observatory and Astrophysics Laboratory, University of Helsinki, SF-00130 Helsinki, Finland

Abstract

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The origin and evolution of contact (W UMa) binaries are discussed with the help of the braking law of eq.(1). Best observationally justified parameter-values in (1) for W UMa, CV and LMXB binaries are: α ≈ 1.5, γ = 2 and f computed from eq.(2). A semi-empirical relation (eq.(5)) between the scaled magnetic torque and the fractional X-ray luminosity is proposed. First attempts of simultaneous photometric and spectroscopic surface imaging of contact binaries are described.

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