Leading & Trailing Spiral Arms in a Nearly Broken Protoplanetary Disc

Fuente: arXiv
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Auteurs principaux: Rowther, Sahl, Nealon, Rebecca, Alexander, Richard, Meru, Farzana
Format: Preprint
Publié: 2025
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author Rowther, Sahl
Nealon, Rebecca
Alexander, Richard
Meru, Farzana
author_facet Rowther, Sahl
Nealon, Rebecca
Alexander, Richard
Meru, Farzana
contents We perform three-dimensional smoothed particle hydrodynamics simulations to investigate the formation of spiral arms in misaligned circumbinary discs. In a nearly broken disc the misaligned inner and outer discs interact at two nodes, launching leading spiral arms that do not rotate with the disc. These spirals vanish when the disc is fully broken or aligned. Our results show that the formation of leading spirals is driven by the relative misalignment of the inner and outer disc, and does not depend on the disc physics. With live radiative transfer, the shadows cast by the misaligned inner disc are also able to launch trailing spiral arms that only appear at high misalignments when the discs are disconnected. When the disc is strongly misaligned, leading and trailing spiral arms can both appear and interact with each other. At lower misalignments, the impact of shadows is negligible and leading spiral arms are seen instead. The presence of both leading and trailing spiral arms implies that the rotation of the disc cannot be assumed based on the orientation of the spiral arms alone. Unlike spirals formed by gravitational instability, the spirals in this work can also form in low-mass, gravitationally stable discs.
format Preprint
id arxiv_https___arxiv_org_abs_2508_04914
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Leading & Trailing Spiral Arms in a Nearly Broken Protoplanetary Disc
Rowther, Sahl
Nealon, Rebecca
Alexander, Richard
Meru, Farzana
Earth and Planetary Astrophysics
We perform three-dimensional smoothed particle hydrodynamics simulations to investigate the formation of spiral arms in misaligned circumbinary discs. In a nearly broken disc the misaligned inner and outer discs interact at two nodes, launching leading spiral arms that do not rotate with the disc. These spirals vanish when the disc is fully broken or aligned. Our results show that the formation of leading spirals is driven by the relative misalignment of the inner and outer disc, and does not depend on the disc physics. With live radiative transfer, the shadows cast by the misaligned inner disc are also able to launch trailing spiral arms that only appear at high misalignments when the discs are disconnected. When the disc is strongly misaligned, leading and trailing spiral arms can both appear and interact with each other. At lower misalignments, the impact of shadows is negligible and leading spiral arms are seen instead. The presence of both leading and trailing spiral arms implies that the rotation of the disc cannot be assumed based on the orientation of the spiral arms alone. Unlike spirals formed by gravitational instability, the spirals in this work can also form in low-mass, gravitationally stable discs.
title Leading & Trailing Spiral Arms in a Nearly Broken Protoplanetary Disc
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2508.04914