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| Main Authors: | , , , , |
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| Format: | Preprint |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2308.08957 |
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| _version_ | 1866911844357111808 |
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| author | Kleeorin, N. Rogachevskii, I. Safiullin, N. Gershberg, R. Porshnev, S. |
| author_facet | Kleeorin, N. Rogachevskii, I. Safiullin, N. Gershberg, R. Porshnev, S. |
| contents | Our theoretical and numerical analysis have suggested that for low-mass main sequences stars (of the spectral classes from M5 to G0) rotating much faster than the Sun, the generated large-scale magnetic field is caused by the mean-field $α^2Ω$ dynamo, whereby the $α^2$ dynamo is modified by a weak differential rotation. Even for a weak differential rotation, the behaviour of the magnetic activity is changed drastically from aperiodic regime to non-linear oscillations and appearance of a chaotic behaviour with increase of the differential rotation. Periods of the magnetic cycles decrease with increase of the differential rotation, and they vary from tens to thousand years. This long-term behaviour of the magnetic cycles may be related to the characteristic time of the evolution of the magnetic helicity density of the small-scale field. The performed analysis is based on the mean-field simulations (MFS) of the $α^2Ω$ and $α^2$ dynamos and a developed non-linear theory of $α^2$ dynamo. The applied MFS model was calibrated using turbulent parameters typical for the solar convective zone. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2308_08957 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Magnetic fields of low-mass main sequences stars: Nonlinear dynamo theory and mean-field numerical simulations Kleeorin, N. Rogachevskii, I. Safiullin, N. Gershberg, R. Porshnev, S. Solar and Stellar Astrophysics Our theoretical and numerical analysis have suggested that for low-mass main sequences stars (of the spectral classes from M5 to G0) rotating much faster than the Sun, the generated large-scale magnetic field is caused by the mean-field $α^2Ω$ dynamo, whereby the $α^2$ dynamo is modified by a weak differential rotation. Even for a weak differential rotation, the behaviour of the magnetic activity is changed drastically from aperiodic regime to non-linear oscillations and appearance of a chaotic behaviour with increase of the differential rotation. Periods of the magnetic cycles decrease with increase of the differential rotation, and they vary from tens to thousand years. This long-term behaviour of the magnetic cycles may be related to the characteristic time of the evolution of the magnetic helicity density of the small-scale field. The performed analysis is based on the mean-field simulations (MFS) of the $α^2Ω$ and $α^2$ dynamos and a developed non-linear theory of $α^2$ dynamo. The applied MFS model was calibrated using turbulent parameters typical for the solar convective zone. |
| title | Magnetic fields of low-mass main sequences stars: Nonlinear dynamo theory and mean-field numerical simulations |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2308.08957 |