Connecting the large- and the small-scale magnetic fields of solar-like stars
Date
21/08/2018Grant ID
ST/R00824/1
ST/M001296/1
Keywords
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Abstract
A key question in understanding the observed magnetic field topologies of cool stars is the link between the small- and the large-scalemagnetic field and the influence of the stellar parameters on the magnetic field topology. We examine various simulated stars to connect the small scale with the observable large-scale field. The highly resolved 3D simulations we used couple a flux transport model with a non-potential coronal model using a magnetofrictional technique. The surface magnetic field of these simulations is decomposed into spherical harmonics which enables us to analyse the magnetic field topologies on a wide range of length scales and to filter the large-scale magnetic field for a direct comparison with the observations. We show that the large-scale field of the self-consistent simulations fits the observed solar-like stars and is mainly set up by the global dipolar field and the large-scale properties of the flux pattern, e.g. the averaged latitudinal position of the emerging small-scale field and its global polarity pattern. The stellar parameter flux emergence rate, differential rotation, and meridional flow affect the large-scale magnetic field topology. An increased flux emergence rate increases the magnetic flux in all field components and an increased differential rotation increases the toroidal field fraction by decreasing the poloidal field. The meridional flow affects the distribution of the magnetic energy across the spherical harmonic modes.
Citation
Lehmann , L T , Jardine , M M , Mackay , D H & Vidotto , A A 2018 , ' Connecting the large- and the small-scale magnetic fields of solar-like stars ' , Monthly Notices of the Royal Astronomical Society , vol. 478 , no. 4 , pp. 4390-4409 . https://doi.org/10.1093/mnras/sty1230
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Rights
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1093/mnras/sty1230
Description
LTL acknowledges support from the Scottish Universities Physics Alliance (SUPA) prize studentship and the University of St Andrews Higgs studentship. MMJ acknowledges the support of the Science & Technology Facilities Council (STFC) (ST/M001296/1).Collections
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