Boundary Layers of Circumplanetary Disks around Spinning Planets II. Global Modes with Azimuthal Magnetic Fields

Fuente: arXiv
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Autores principales: Fu, Zhihao, Huang, Shunquan, Yu, Cong
Formato: Preprint
Publicado: 2024
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author Fu, Zhihao
Huang, Shunquan
Yu, Cong
author_facet Fu, Zhihao
Huang, Shunquan
Yu, Cong
contents The accretion of material from disks onto weakly magnetized objects invariably involves its traversal through a material surface, known as the boundary layer (BL). Our prior studies have revealed two distinct global wave modes for circumplanetary disks (CPDs) with BLs exhibit opposite behaviors in spin modulation.We perform a detailed analysis about the effect of magnetic fields on these global modes, highlighting how magnetic resonances and turning points could complicate the wave dynamics. The angular momentum flux becomes positive near the BL with increasing magnetic field strength. We also examine the perturbation profile to demonstrate the amplification of magnetic fields within the BL. The dependence of growth rates on the magnetic field strength, and the spin rate are systematically investigated. We find that stronger magnetic fields tend to result in lower terminal spin rates. We stress the potential possibility for the formation of angular momentum belts and pressure bumps. The implication for the spin evolution and quasi-period oscillations observed in compact objects are also briefly discussed. Our calculations advance the understanding of magnetohydrodynamical (MHD) accretion processes and lays a foundation for observational studies and numerical simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2408_16376
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Boundary Layers of Circumplanetary Disks around Spinning Planets II. Global Modes with Azimuthal Magnetic Fields
Fu, Zhihao
Huang, Shunquan
Yu, Cong
Earth and Planetary Astrophysics
High Energy Astrophysical Phenomena
The accretion of material from disks onto weakly magnetized objects invariably involves its traversal through a material surface, known as the boundary layer (BL). Our prior studies have revealed two distinct global wave modes for circumplanetary disks (CPDs) with BLs exhibit opposite behaviors in spin modulation.We perform a detailed analysis about the effect of magnetic fields on these global modes, highlighting how magnetic resonances and turning points could complicate the wave dynamics. The angular momentum flux becomes positive near the BL with increasing magnetic field strength. We also examine the perturbation profile to demonstrate the amplification of magnetic fields within the BL. The dependence of growth rates on the magnetic field strength, and the spin rate are systematically investigated. We find that stronger magnetic fields tend to result in lower terminal spin rates. We stress the potential possibility for the formation of angular momentum belts and pressure bumps. The implication for the spin evolution and quasi-period oscillations observed in compact objects are also briefly discussed. Our calculations advance the understanding of magnetohydrodynamical (MHD) accretion processes and lays a foundation for observational studies and numerical simulations.
title Boundary Layers of Circumplanetary Disks around Spinning Planets II. Global Modes with Azimuthal Magnetic Fields
topic Earth and Planetary Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2408.16376