Volume 569, September 2014
|Number of page(s)||8|
|Section||Stellar structure and evolution|
|Published online||26 September 2014|
ϵ Eridani: an active K dwarf and a planet hosting star?
The variability of its large-scale magnetic field topology⋆
Institut für Astrophysik, Georg-August-Universität,
2 Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysique et Planétologie, Toulouse, France
3 Institut de Recherche en Astrophysique et Planétologie, 14 avenue Edouard Belin, 31400 Toulouse, France
4 Computational Engineering and Science Research Centre, University of Southern Queensland, 4350 Toowoomba, Australia
5 LUPM, UMR 5299, CNRS & Université Montpellier II, Place E. Bataillon, 34095 Montpellier Cedex 05, France
Received: 27 February 2014
Accepted: 1 July 2014
The young K-dwarf ϵ Eridani is an example of a young active planet hosting star that has shown over long-term monitoring of its chromospheric emission to exhibit cyclic magnetic activity. In this paper, we investigate how ϵ Eridani’s large-scale magnetic field geometry evolves over the timescale of its S-index cycle using spectropolarimetric observations and the technique of Zeeman-Doppler imaging. Our observations comprise six epochs secured over a time period of nearly seven years, with each almost yearly observational epoch showing a dramatic change in the large-scale magnetic field topology, with no stable regions. The poloidal field varies from strongly dipolar to mono-polar and the toroidal field is non-existent to begin with and then emerges to dominate the magnetic field energy before disappearing and re-emerging again. A potential cycle is detected in the poloidal field, but further observations are needed to confirm this.
Key words: magnetic fields / stars: activity / stars: magnetic field / starspots
© ESO, 2014
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.