Magnetic fields on young, moderately rotating Sun-like stars – II. EK Draconis (HD 129333)

Waite, I. A. and Marsden, S. C. and Carter, B. D. and Petit, P. and Jeffers, S. V. and Morin, J. and Vidotto, A. A. and Donati, J.-F. and BCool Collaboration, (2017) Magnetic fields on young, moderately rotating Sun-like stars – II. EK Draconis (HD 129333). Monthly Notices of the Royal Astronomical Society, 465 (2). pp. 2076-2091. ISSN 0035-8711

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Abstract

The magnetic fields, activity and dynamos of young solar-type stars can be empirically studied using time series of spectropolarimetric observations and tomographic imaging techniques such as Doppler imaging and Zeeman–Doppler imaging. In this paper, we use these techniques to study the young Sun-like star EK Draconis (SpType: G1.5V, HD 129333) using ESPaDOnS at the Canada–France–Hawaii Telescope and NARVAL at the Telescope Bernard Lyot. This multi-epoch study runs from late 2006 until early 2012. We measure high levels of chromospheric activity indicating an active, and varying, chromosphere. Surface brightness features were constructed for all available epochs. The 2006/2007 and 2008 data show large spot features appearing at intermediate latitudes. However, the 2012 data indicate a distinctive polar spot. We observe a strong, almost unipolar, azimuthal field during all epochs, which is similar to that observed on other Sun-like stars. Using magnetic features, we determined an average equatorial rotational velocity,Omega_eq, of ∼2.50 ± 0.08 rad d−1. High levels of surface differential rotation were measured with an average rotational shear, Delta_Omega, of ∼0.27 +0.24−0.26 rad d−1. During an intensively observed 3-month period, from 2006 December until 2007 February, the
magnetic field went from predominantly toroidal (∼80 per cent) to a more balanced poloidal–toroidal (∼40–60 per cent) field. Although the large-scale magnetic field evolved over the epochs of our observations, no polarity reversals were found in our data.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to Published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 19 Jan 2018 05:49
Last Modified: 19 Jan 2018 06:07
Uncontrolled Keywords: stars, HD 129333, magnetic fields, starspots
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1093/mnras/stw2731
URI: http://eprints.usq.edu.au/id/eprint/33570

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