Title

Linear Analysis of the Evolution of Nearly Polar Low-mass Circumbinary Discs

Document Type

Article

Publication Date

10-11-2017

Publication Title

Monthly Notices of the Royal Astronomical Society

Volume

473

Issue

3

First page number:

3733

Last page number:

3746

Abstract

In a recent paper Martin & Lubow showed through simulations that an initially tilted disc around an eccentric binary can evolve to polar alignment in which the disc lies perpendicular to the binary orbital plane.We apply linear theory to show both analytically and numerically that a nearly polar aligned low-mass circumbinary disc evolves to polar alignment and determine the alignment time-scale. Significant disc evolution towards the polar state around moderately eccentric binaries can occur for typical protostellar disc parameters in less than a typical disc lifetime for binaries with orbital periods of order 100 yr or less. Resonant torques are much less effective at truncating the inner parts of circumbinary polar discs than the inner parts of coplanar discs. For polar discs, they vanish for a binary eccentricity of unity. The results agree with the simulations in showing that discs can evolve to a polar state. Circumbinary planets may then form in such discs and reside on polar orbits.

Keywords

Accretion; Accretion discs; Binaries: General; Hydrodynamics; Planets and satellites: Formation

Disciplines

Astrophysics and Astronomy

Language

English

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