Authors

M. M. Montgomery;E. L. Martin

Comments

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Abbreviated Journal Title

Astrophys. J.

Keywords

accretion, accretion disks; hydrodynamics; instabilities; methods:; analytical; planet-disk interactions; protoplanetary disks; X-RAY BINARIES; NEGATIVE SUPERHUMPS; PROTOSTELLAR DISCS; CATACLYSMIC; VARIABLES; LONG PERIODS; HERCULIS X-1; YOUNG STARS; ORIGIN; SIMULATIONS; PRECESSION; Astronomy & Astrophysics

Abstract

Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source that causes and maintains disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through the disk's center of mass. The disk responds to lift by pitching around the disk's line of nodes. If the gas stream flow ebbs, then lift also ebbs and the disk attempts to return to its original orientation. To first approximation, lift does not depend on magnetic fields or radiation sources but does depend on the mass and the surface area of the disk. Also, for disk tilt to be initiated, a minimum mass transfer rate must be exceeded. For example, a 10(-11) M(circle dot) disk around a 0.8 M(circle dot) compact central object requires a mass transfer rate greater than similar to 8 x 10(-11) M(circle dot) yr(-1), a value well below the known mass transfer rates in cataclysmic variable dwarf novae systems that retrogradely precess and exhibit negative superhumps in their light curves and a value well below mass transfer rates in protostellar-forming systems.

Journal Title

Astrophysical Journal

Volume

722

Issue/Number

2

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

989

Last Page

996

WOS Identifier

WOS:000284075400002

ISSN

0004-637X

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