Dr. Sacha Brun- CEA Paris-Saclay - seminar (Mon 7th June 2021)
Duration: 1 hour 6 mins
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| Description: |
Powering Stellar Magnetism: Energy Transfers in Convective Dynamo
of Sun-like Stars |
|---|
| Created: | 2021-06-07 20:23 |
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| Collection: | DAMTP Astro Seminars |
| Publisher: | University of Cambridge |
| Copyright: | Zhao Guo |
| Language: | eng (English) |
| Distribution: |
World
(downloadable)
|
| Explicit content: | No |
| Aspect Ratio: | 4:3 |
| Screencast: | No |
| Bumper: | UCS Default |
| Trailer: | UCS Default |
| Abstract: | We present recent advances made to understand the origin of
stellar magnetism thanks to an extensive 3D MHD study of convective dynamo of solar-type stars. We aim at characterising the detailed energy transfers occurring in these model stars and the type of dynamos realised (statistically steady, cyclic on either long or short time scales), depending on the stellar global parameters considered. We confirm that the Rossby number is a good proxy to identify key transitions for the different dynamical behaviours found in our study. We also propose various scaling laws for the large scale field, magnetic flux and surface differential rotation that are qualitatively in good agreement with observations of stellar magnetism. We also quantify the amount of stellar energy converted into magnetic energy finding that there is plenty of energy (up to 3% of the stellar luminosity) made available to power surface eruptive events. We conclude by discussing the so-called spot-dynamo paradox, e.g.are starspots playing or not a key role in the operation of stellar cyclic dynamos? |
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