∊ Eridani: an active K dwarf and a planet hosting star?. The variability of its large-scale magnetic field topology
∊ Eridani: an active K dwarf and a planet hosting star?. The variability of its large-scale magnetic field topology
复制标题
â 波江座：一颗活跃的 K 矮星和一颗拥有恒星的行星？
DOI：
10.1051/0004-6361/201423725
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发表时间：
2014
影响因子：
6.5
通讯作者：
Marsden
中科院分区：
文献类型：
--
作者：
Jeffers;Marsden
年轻的K-矮星Eridani是一颗年轻的活跃行星托管恒星的一个例子，通过对它的色球发射的长期监测，它显示出周期性的磁活动。在本文中，我们利用分光偏振观测和塞曼-多普勒成像技术研究了εEridani 的大尺度磁场几何形状如何在其 S 指数周期的时间尺度上演化。我们的观测包括在近七年的时间内固定的六个历元，每个观测历元几乎每年都显示出大规模磁场拓扑的巨大变化，没有稳定的区域。极向场从强偶极到单极变化，环形场一开始不存在，然后出现并主导磁场能量，然后消失并再次出现。在极向场中检测到潜在的循环，但需要进一步的观察来证实这一点。
The young K-dwarfϵEridani 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 howϵEridani’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.