Stellar magnetism: empirical trends with age and rotation

Vidotto, A. A. and Gregory, S. G. and Jardine, M. and Donati, J. -F. and Petit, P. and Morin, J. and Folsom, C. P. and Bouvier, J. and Cameron, A. C. and Hussain, G. and Marsden, S. and Waite, I. A. and Fares, R. and Jeffers, S. and do Nascimento Jr., J.-D. (2014) Stellar magnetism: empirical trends with age and rotation. Monthly Notices of the Royal Astronomical Society, 441 (3). pp. 2361-2374. ISSN 0035-8711

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Abstract

We investigate how the observed large-scale surface magnetic fields of low-mass stars (̃0.1-2M⊙), reconstructed through Zeeman-Doppler imaging, vary with age t, rotation and X-ray emission. Our sample consists of 104 magnetic maps of 73 stars, from accreting premain sequence to main-sequence objects (1 Myr ≲ t ≲ 10 Gyr). For non-accreting dwarfs we empirically find that the unsigned average large-scale surface field is related to age as t-0.655 ± 0.045. This relation has a similar dependence to that identified by Skumanich, used as the basis for gyrochronology. Likewise, our relation could be used as an age-dating method ('magnetochronology'). The trends with rotation we find for the large-scale stellar magnetism are consistent with the trends found from Zeeman broadening measurements (sensitive to large-and small-scale fields). These similarities indicate that the fields recovered from both techniques are coupled to each other, suggesting that small-and large-scale fields could share the same dynamo field generation processes. For the accreting objects, fewer statistically significant relations are found, with one being a correlation between the unsigned magnetic flux and rotation period. We attribute this to a signature of star-disc interaction, rather than being driven by the dynamo.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2014 The Authors. This publication is copyright. It may be reproduced in whole or in part for the purposes of study, research, or review, but is subject to the inclusion of an acknowledgment of the source.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 30 Jul 2014 04:22
Last Modified: 04 Jul 2016 06:02
Uncontrolled Keywords: planetary systems; stars; evolution; magnetic field; rotation; polarimetric techniques
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020109 Space and Solar Physics
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020107 Mesospheric, Ionospheric and Magnetospheric Physics
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1093/mnras/stu728
URI: http://eprints.usq.edu.au/id/eprint/25465

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