Does Betelgeuse Have a Magnetic Field?
Abstract
Recent numerical simulations by Freytag et al. of the outer convection envelope of the cool super-giant Betelgeuse, have shown that the fluctuations in the star's apparent luminosity may be caused by giant cell convection. These simulations bring forth the possibility of addressing another question; namely whether stars such as Betelgeuse may harbor magnetic activity. Taking the detailed numerical simulations of the star at face value, we have applied a kinematic dynamo analysis, to study whether the flow field of the super-giant may be able to amplify a weak seed magnetic field. We do indeed find a positive exponential growth rate of the magnetic energy. The possible Betelgeusian dynamo may be characterized as belonging to the class of so-called ``local small-scale dynamos'' (i.e. dynamos where rotation is not dominant), but this is a less meaningful designation in the case of Betelgeuse, since the field is both global and large-scale.
- Publication:
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Modelling of Stellar Atmospheres
- Pub Date:
- 2003
- DOI:
- 10.48550/arXiv.astro-ph/0208523
- arXiv:
- arXiv:astro-ph/0208523
- Bibcode:
- 2003IAUS..210P.A12D
- Keywords:
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- Astrophysics
- E-Print:
- Proceedings of IAU Symp. 210. 10 pages, 8 figures (2 color)