Magnetic fields in fully convective M-dwarfs: oscillatory dynamos versus bistability

Авторы: Kitchatinov L.L., Moss D., Sokoloff D.
Журнал: Monthly Notices of the Royal Astronomical Society
Год издания: 2014
Издательство: Oxford Journals, Oxford University Press
Местоположение издательства: Oxford, UK, England
DOI: 10.1093/mnrasl/slu041
Аннотация: M-dwarfs demonstrate two types of activity: (1) strong (kilogauss) almost axisymmetric poloidal magnetic fields; and (2) considerably weaker non-axisymmetric fields, sometimes including a substantial toroidal component. Dynamo bistability has been proposed as an explanation. However, it is not straightforward to obtain such a bistability in dynamo models. On the other hand, the solar magnetic dipole at times of magnetic field inversion becomes transverse to the rotation axis, while the magnetic field becomes weaker at times far from that of inversion. Thus, the Sun resembles a star with the second type of activity. We suggest that M-dwarfs can have magnetic cycles, and that M-dwarfs with the second type of activity can just be stars observed at times of magnetic field inversion. Then the relative number of M-dwarfs with the second type of activity can be used in the framework of this model to determine parameters of stellar convection near the surface.
Добавил в систему: Соколов Дмитрий Дмитриевич

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