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Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2014

ɛ Eridani: an active K dwarf and a planet hosting star?. The variability of its large-scale magnetic field topology

Résumé

The young K-dwarf ɛ 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 ɛ 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.
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Dates et versions

hal-01770030 , version 1 (18-04-2018)

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Sandra V. Jeffers, Pascal Petit, Stephen C. Marsden, Julien Morin, Jean-François Donati, et al.. ɛ Eridani: an active K dwarf and a planet hosting star?. The variability of its large-scale magnetic field topology. Monthly Notices of the Royal Astronomical Society, 2014, 569, pp.A79. ⟨10.1051/0004-6361/201423725⟩. ⟨hal-01770030⟩
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