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arXiv · 1503.06662

Magnetic field measurements of $ε$ Eridani from Zeeman broadening

L. T. Lehmann·A. Künstler·T. A. Carroll·K. G. Strassmeier
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Abstract

We present new magnetic field measurements of the K2 main-sequence star $ε$ Eridani based on principal components analysis (PCA) line-profile reconstructions. The aim of this paper is to quantify the surface-averaged magnetic field and search for possible variations. A total of 338 optical echelle spectra from our robotic telescope facility STELLA with a spectral resolution of 55,000 were available for analysis. This time-series was used to search for the small line-profile variations due to a surface magnetic field with the help of a PCA. Evidence for a spatial and temporal inhomogeneous magnetic field distribution is presented. The mean, surface averaged, magnetic field strength was found to be $\langle B \rangle = 186 \pm 47\,\mathrm{G}$ in good agreement with previous Zeeman-broadening measurements. Clear short-term variations of the surface averaged magnetic field of up to few tens Gauss were detected together with evidence for a three-year cycle in the surface-averaged magnetic field of $ε$ Eridani.

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L. T. Lehmann, A. Künstler, T. A. Carroll, K. G. Strassmeier. 2015-03-23. Magnetic field measurements of $ε$ Eridani from Zeeman broadening. https://doi.org/10.1002/asna.201412162

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