Direct evidence of a full dipole flip during the magnetic cycle of a sun-like star
Direct evidence of a full dipole flip during the magnetic cycle of a sun-like star
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类太阳恒星磁周期期间偶极子翻转的直接证据
DOI：
10.1051/0004-6361/201834347
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发表时间：
2018
影响因子：
6.5
通讯作者：
the Bcool Collaboration
中科院分区：
文献类型：
--
作者：
S. Saikia;T. Lueftinger;S. Jeffers;C. Folsom;V. See;P. Petit;S. Marsden;A. Vidotto;J. Morin;A. Reiners;M. Guedel;the Bcool Collaboration
背景。在恒星磁周期期间，大尺度偶极场的行为可以为了解恒星发电机和相关磁场表现（如恒星风）提供有价值的见解。目标。我们利用分光偏振观测研究 K 矮星 61 Cyg A 偶极场的时间演化，覆盖近一个磁周期相当于两个色球活动周期。方法。使用塞曼多普勒重建大尺度磁场几何形状成像，一种断层扫描反演技术。此外，还监测了色球活动。结果。这些观测提供了对太阳以外恒星的单个磁周期内的大规模场的前所未有的采样。我们的结果表明，除色球活动最大值外，61 Cyg A 具有占主导地位的偶极几何结构。在磁周期期间，偶极轴从南半球迁移到北半球。它位于色球活动周期最小值时的高纬度地区和周期最大值期间的中纬度地区。偶极子在活动周期最小值时最强，在活动周期最大值时弱得多。结论。磁周期期间大尺度偶极场的行为类似于太阳磁周期。我们的结果进一步证实了 61 Cyg A 确实具有与太阳相当的大规模磁几何结构，尽管它是一颗稍微古老且温度较低的 K 矮星。
Context.The behaviour of the large-scale dipolar field, during a star’s magnetic cycle, can provide valuable insight into the stellar dynamo and associated magnetic field manifestations such as stellar winds.Aims.We investigate the temporal evolution of the dipolar field of the K dwarf 61 Cyg A using spectropolarimetric observations covering nearly one magnetic cycle equivalent to two chromospheric activity cycles.Methods.The large-scale magnetic field geometry is reconstructed using Zeeman Doppler imaging, a tomographic inversion technique. Additionally, the chromospheric activity is also monitored.Results.The observations provide an unprecedented sampling of the large-scale field over a single magnetic cycle of a star other than the Sun. Our results show that 61 Cyg A has a dominant dipolar geometry except at chromospheric activity maximum. The dipole axis migrates from the southern to the northern hemisphere during the magnetic cycle. It is located at higher latitudes at chromospheric activity cycle minimum and at middle latitudes during cycle maximum. The dipole is strongest at activity cycle minimum and much weaker at activity cycle maximum.Conclusions.The behaviour of the large-scale dipolar field during the magnetic cycle resembles the solar magnetic cycle. Our results are further confirmation that 61 Cyg A indeed has a large-scale magnetic geometry that is comparable to the Sun’s, despite being a slightly older and cooler K dwarf.
影响因子：
6.5
作者：
S. Saikia;S. Jeffers;J. Morin;P. Petit;P. Petit;C. Folsom;S. Marsden;J. Donati;J. Donati;R. H. Cameron;J. C. Hall;V. Perdelwitz;A. Reiners;A. Vidotto;A. Vidotto
通讯作者：
S. Saikia;S. Jeffers;J. Morin;P. Petit;P. Petit;C. Folsom;S. Marsden;J. Donati;J. Donati;R. H. Cameron;J. C. Hall;V. Perdelwitz;A. Reiners;A. Vidotto;A. Vidotto
â 波江座：一颗活跃的 K 矮星和一颗拥有恒星的行星？
影响因子：
6.5
作者：
Jeffers;Marsden
通讯作者：
Marsden
年轻太阳 HN Pegasi (HD 206860) 的可变磁场几何结构
影响因子：
6.5
作者：
Boro Saikia;Jeffers
通讯作者：
Jeffers