Contact Binaries

Ronald F. Webbink

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arXiv · astro-ph/0304420

Contact Binaries

Ronald F. Webbink

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Abstract

Despite being the most abundant (by space density) of interacting binary stars, W Ursae Majoris (W UMa) stars are not understood structurally. Their stellar components are in physical contact, and share a common convective envelope. Observations demand large-scale energy exchange between components, as do considerations of hydrostatic and thermal equilibrium. Yet solutions in complete equilibrium can account for only a few of the bluest W UMa binaries. Models which permit departures from thermal equilibrium can reproduce the observable properties of later-type W UMa binaries, but they develop relaxation oscillations, during a substantial portion of which the binary components break thermal contact and develop very different effective temperatures, contrary to observational statistics. Massive, early-type contact binaries are also known to exist, but the nature of energy and mass exchange in common radiative envelopes remains virtually unexplored.

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Ronald F. Webbink. 2003-04-23. Contact Binaries. https://arxiv.org/abs/astro-ph/0304420

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