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The relation between stellar magnetic field geometry and chromospheric activity cycles - I. The highly variable field of ɛ Eridani at activity minimum

Jeffers, S. V.; Boro, S. S.; Barnes, J. R.; Petit, P.; Marsden, S. C.; Jardine, M. M.; Vidotto, A. A. and the BCool collaboration (2017). The relation between stellar magnetic field geometry and chromospheric activity cycles - I. The highly variable field of ɛ Eridani at activity minimum. Monthly Notices of the Royal Astronomical Society: Letters, 471(1) L96-L100.

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DOI (Digital Object Identifier) Link: https://doi.org/10.1093/mnrasl/slx097
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Abstract

The young and magnetically active K dwarf Epsilon Eridani exhibits a chromospheric activity cycle of about 3 years. Previous reconstructions of its large-scale magnetic field show strong variations at yearly epochs. To understand how Epsilon Eridani's large-scale magnetic field geometry evolves over its activity cycle we focus on high cadence observations spanning 5 months at its activity minimum. Over this timespan we reconstruct 3 maps of Epsilon Eridani's large-scale magnetic field using the tomographic technique of Zeeman Doppler Imaging. The results show that at the minimum of its cycle, Epsilon Eridani's large-scale field is more complex than the simple dipolar structure of the Sun and 61 Cyg A at minimum. Additionally we observe a surprisingly rapid regeneration of a strong axisymmetric toroidal field as Epsilon Eridani emerges from its S-index activity minimum. Our results show that all stars do not exhibit the same field geometry as the Sun and this will be an important constraint for the dynamo models of active solar-type stars.

Item Type: Journal Item
Copyright Holders: 2017 MNRAS
ISSN: 1745-3933
Project Funding Details:
Funded Project NameProject IDFunding Body
Consolidated grantST/L000776/1STFC
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Health and Wellbeing PRA (Priority Research Area)
Item ID: 53382
Depositing User: John Barnes
Date Deposited: 09 Feb 2018 16:09
Last Modified: 10 May 2019 08:58
URI: http://oro.open.ac.uk/id/eprint/53382
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