Document Type

Article

Publication Date

3-11-2022

Publication Title

The Astrophysical Journal Letters

Volume

927

Issue

2

First page number:

1

Last page number:

7

Abstract

We consider a hierarchical triple system consisting of an inner eccentric binary with an outer companion. A highly misaligned circumbinary disk around the inner binary is subject to two competing effects: (i) nodal precession about the inner binary eccentricity vector that leads to an increase in misalignment (polar alignment) and (ii) Kozai–Lidov (KL) oscillations of eccentricity and inclination driven by the outer companion that leads to a reduction in the misalignment. The outcome depends upon the ratio of the timescales of these effects. If the inner binary torque dominates, then the disk aligns to a polar orientation. If the outer companion torque dominates, then the disk undergoes KL oscillations. In that case, the highly eccentric and misaligned disk is disrupted and accreted by the inner binary, while some mass is transferred to the outer companion. However, when the torques are similar, the outer parts of the circumbinary disk can undergo large eccentricity oscillations while the inclination remains close to polar orientation. The range of initial disk inclinations that evolve to a polar orientation is smaller in the presence of the outer companion. Disk breaking is also more likely, at least temporarily, during the polar alignment process. The stellar orbits in HD 98800 have parameters such that polar alignment of the circumbinary disk is expected. In the absence of gas, solid particles are unstable at much smaller radii than the gas-disk inner tidal truncation radius because KL-driven eccentricity leads to close encounters with the binary.

Keywords

Accretion; Stellar accretion disls, Circumstellar disks; Protoplanetary disks; Trinary stars; Binary stars; Hydrodynamics; Exoplanet formation; Planet formation

Disciplines

Stars, Interstellar Medium and the Galaxy

File Format

PDF

File Size

802 KB

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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