%0 Journal Article
%T Magnetic field measurements of $¦Å$ Eridani from Zeeman broadening
%A L. T. Lehmann
%A A. K¨¹nstler
%A T. A. Carroll
%A K. G. Strassmeier
%J Physics
%D 2015
%I arXiv
%R 10.1002/asna.201412162
%X We present new magnetic field measurements of the K2 main-sequence star $\epsilon$ 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 $\epsilon$ Eridani.
%U http://arxiv.org/abs/1503.06662v1