Magnetic fields of low-mass main sequences stars: non-linear dynamo theory and mean-field numerical simulations

Author:

Kleeorin N12,Rogachevskii I13,Safiullin N24,Gershberg R5,Porshnev S46

Affiliation:

1. Department of Mechanical Engineering, Ben-Gurion University of Negev , POB 653, 8410530 Beer-Sheva , Israel

2. Institute of Continuous Media Mechanics , Korolyov str 1, Perm 614013 , Russia

3. Nordita, KTH Royal Institute of Technology and Stockholm University , Roslagstullsbacken 23, SE-10691 Stockholm , Sweden

4. Department of Radio Electronic and Informational Technology, Ural Federal University , 19 Mira str, 620002 Ekaterinburg , Russia

5. Crimean Astrophysical Observatory , RAN, 298409 Nauchny , Russia

6. N.N. Krasovskii Institute of Mathematics and Mechanics (IMM UB RAS) , 620108 Ekaterinburg , Russia

Abstract

ABSTRACT 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 α2Ω dynamo, whereby the α2 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 α2Ω and α2 dynamos and a developed non-linear theory of α2 dynamo. The applied MFS model was calibrated using turbulent parameters typical for the solar convective zone.

Funder

Russian Science Foundation

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 2 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Correlations between Ca ii H and K Emission and the Gaia M Dwarf Gap;The Astrophysical Journal;2024-04-01

2. Budget equations and astrophysical non-linear mean-field dynamos;Monthly Notices of the Royal Astronomical Society;2024-03-06

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