The polar debris disc around 99 Herculis: A potential signpost for polar circumbinary planets

Fuente: arXiv
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Hauptverfasser: Smallwood, Jeremy L., DeRocco, William, Qin, Zhizhen, Sefilian, Antranik A.
Format: Preprint
Veröffentlicht: 2025
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author Smallwood, Jeremy L.
DeRocco, William
Qin, Zhizhen
Sefilian, Antranik A.
author_facet Smallwood, Jeremy L.
DeRocco, William
Qin, Zhizhen
Sefilian, Antranik A.
contents The nearby binary star system 99 Herculis (99 Her) is host to the only known polar-aligned circumbinary debris disc. We investigate the hypothesis that the narrow structure of this circumbinary disc is sculpted by the gravitational influence of one or more unseen polar circumbinary planets. We first establish the theoretically viable parameter space for a sculpting planet by considering dynamical stability and clearing mechanisms, including the chaotic zone, Hill radius, diffusion, and polar alignment timescales. We then use $N$-body simulations to test three specific architectures: a single planet interior to the disc, a single planet exterior, and a two-planet system bracketing the disc. Our simulations demonstrate that single-planet models are insufficient to reproduce the observed morphology, as they can only truncate one edge of the disc while leaving the other dynamically extended. In contrast, the two-planet shepherding model successfully carves both the inner and outer edges, confining the debris into a narrow, stable polar ring consistent with observations. We conclude that the structure of the 99 Her debris disc is most plausibly explained by the presence of two shepherding, polar circumbinary planets. We present a specific, testable model for this unique system, which elucidates the pivotal role of planetary bodies in sculpting the architecture of debris discs.
format Preprint
id arxiv_https___arxiv_org_abs_2510_08698
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The polar debris disc around 99 Herculis: A potential signpost for polar circumbinary planets
Smallwood, Jeremy L.
DeRocco, William
Qin, Zhizhen
Sefilian, Antranik A.
Earth and Planetary Astrophysics
The nearby binary star system 99 Herculis (99 Her) is host to the only known polar-aligned circumbinary debris disc. We investigate the hypothesis that the narrow structure of this circumbinary disc is sculpted by the gravitational influence of one or more unseen polar circumbinary planets. We first establish the theoretically viable parameter space for a sculpting planet by considering dynamical stability and clearing mechanisms, including the chaotic zone, Hill radius, diffusion, and polar alignment timescales. We then use $N$-body simulations to test three specific architectures: a single planet interior to the disc, a single planet exterior, and a two-planet system bracketing the disc. Our simulations demonstrate that single-planet models are insufficient to reproduce the observed morphology, as they can only truncate one edge of the disc while leaving the other dynamically extended. In contrast, the two-planet shepherding model successfully carves both the inner and outer edges, confining the debris into a narrow, stable polar ring consistent with observations. We conclude that the structure of the 99 Her debris disc is most plausibly explained by the presence of two shepherding, polar circumbinary planets. We present a specific, testable model for this unique system, which elucidates the pivotal role of planetary bodies in sculpting the architecture of debris discs.
title The polar debris disc around 99 Herculis: A potential signpost for polar circumbinary planets
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2510.08698