Non-ideal Magnetohydrodynamic Instabilities in Protoplanetary Disks: Vertical Modes and Reflection Asymmetry
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arXiv
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| Auteurs principaux: | , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866909240100126720 |
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| author | Wang, Lile Xu, Sheng Wang, Zhenyu Fang, Min Goodman, Jeremy |
| author_facet | Wang, Lile Xu, Sheng Wang, Zhenyu Fang, Min Goodman, Jeremy |
| contents | Magnetized disk winds and wind-driven accretion are an essential and intensively studied dispersion mechanism of protoplanetary disks. However, the stability of these mechanisms has yet to be adequately examined. This paper employs semi-analytic linear perturbation theories under non-ideal magnetohydrodynamics, focusing on disk models whose magnetic diffusivities vary by a few orders of magnitude from the disk midplane to its surface. Linear modes are distinguished by their symmetry with respect to the midplane. These modes have qualitatively different growth rates: symmetric modes almost always decay, while at least one anti-symmetric mode always has a positive growth rate. This growth rate decreases faster than the Keplerian angular velocity with cylindrical radius $R$ in the disk and scales steeper than $R^{-5/2}$ in the fiducial disk model. The growth of anti-symmetric modes breaks the reflection symmetry across the disk equatorial plane, and may occur even in the absence of the Hall effect. In the disk regions where fully developed anti-symmetric modes occur, accretion flows appear only on one side of the disk, while disk winds occur only on the other. This may explain the asymmetry of some observed protoplanetary-disk outflows. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2311_01636 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Non-ideal Magnetohydrodynamic Instabilities in Protoplanetary Disks: Vertical Modes and Reflection Asymmetry Wang, Lile Xu, Sheng Wang, Zhenyu Fang, Min Goodman, Jeremy Earth and Planetary Astrophysics Solar and Stellar Astrophysics Magnetized disk winds and wind-driven accretion are an essential and intensively studied dispersion mechanism of protoplanetary disks. However, the stability of these mechanisms has yet to be adequately examined. This paper employs semi-analytic linear perturbation theories under non-ideal magnetohydrodynamics, focusing on disk models whose magnetic diffusivities vary by a few orders of magnitude from the disk midplane to its surface. Linear modes are distinguished by their symmetry with respect to the midplane. These modes have qualitatively different growth rates: symmetric modes almost always decay, while at least one anti-symmetric mode always has a positive growth rate. This growth rate decreases faster than the Keplerian angular velocity with cylindrical radius $R$ in the disk and scales steeper than $R^{-5/2}$ in the fiducial disk model. The growth of anti-symmetric modes breaks the reflection symmetry across the disk equatorial plane, and may occur even in the absence of the Hall effect. In the disk regions where fully developed anti-symmetric modes occur, accretion flows appear only on one side of the disk, while disk winds occur only on the other. This may explain the asymmetry of some observed protoplanetary-disk outflows. |
| title | Non-ideal Magnetohydrodynamic Instabilities in Protoplanetary Disks: Vertical Modes and Reflection Asymmetry |
| topic | Earth and Planetary Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2311.01636 |