The energy budget of stellar magnetic fields: comparing non-potential simulations and observations
Article
Article Title | The energy budget of stellar magnetic fields: comparing non-potential simulations and observations |
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ERA Journal ID | 41989 |
Article Category | Article |
Authors | Lehmann, L. T. (Author), Jardine, M. M. (Author), Vidotto, A. A. (Author), Mackay, D. H. (Author), See, V. (Author), Donati, J.-F. (Author), Folsom, C. P. (Author), Jeffers, S. V. (Author), Marsden, S. C. (Author), Morin, J. (Author) and Petit, P. (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society: Letters |
Journal Citation | 466 (1), pp. L24-L28 |
Number of Pages | 5 |
Year | 2017 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 1745-3925 |
1745-3933 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnrasl/slw225 |
Web Address (URL) | https://academic.oup.com/mnrasl/article/466/1/L24/2417281 |
Abstract | The magnetic geometry of the surface magnetic fields of more than 55 cool stars have now been mapped using spectropolarimetry. In order to better understand these observations, we compare the magnetic field topology at different surface scale sizes of observed and simulated cool stars. For ease of comparison between the high-resolution non-potential magnetofrictional simulations and the relatively low-resolution observations, we filter out the small-scale field in the simulations using a spherical harmonics decomposition. We show that the large-scale field topologies of the solar-based simulations produce values of poloidal/toroidal fields and fractions of energy in axisymmetric modes which are similar to the observations. These global non-potential evolution model simulations capture key magnetic features of the observed solar-like stars through the processes of surface flux transport and magnetic flux emergence. They do not, however, reproduce the magnetic field of M-dwarfs or stars with dominantly toroidal field. Furthermore, we analyse the magnetic field topologies of individual spherical harmonics for the simulations and discover that the dipole is predominately poloidal, while the quadrupole shows the highest fraction of toroidal fields. Magnetic field structures smaller than a quadrupole display a fixed ratio between the poloidal and toroidal magnetic energies. |
Keywords | stars, magnetic fields, solar-type |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Byline Affiliations | University of St Andrews, United Kingdom |
University of Dublin, Ireland | |
University of Toulouse, France | |
Georg August University of Gottingen, Germany | |
Computational Engineering and Science Research Centre | |
University of Montpellier, France | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q488x/the-energy-budget-of-stellar-magnetic-fields-comparing-non-potential-simulations-and-observations
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