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arXiv 2602.15979astro-ph.SRastro-ph.EPastro-ph.IM
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多波段观测年轻太阳型恒星EK Draconis III. 星斑映射、Zeeman Doppler成像与多波段变异性之间的比较

Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. III. Comparison between Starspot Mapping, Zeeman Doppler Imaging, and Multiwavelength Variability

Hitotsubashi University（一桥大学）；The University of Tokyo（东京大学）；The Hakubi Center for Advanced Research, Kyoto University（京都大学博雅研究高级中心）；Department of Physics, Kyoto University（京都大学物理学系）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；Department of Physics, The Catholic University of America（美利坚天主教大学物理学系）；Division of Science, National Astronomical Observatory of Japan, NINS（日本国立天文台科学部）；Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, CNRS, CNES（图卢兹大学、法国国家科学研究中心、法国国家空间研究中心天体物理与行星学研究所在）；Department of Physics, American University（美国大学物理学系）
Kai Ikuta, Kosuke Namekata, Pascal Petit, Vladimir S. Airapetian, Hiroyuki Maehara, Yuta Notsu, Aline A. Vidotto, Keith Gendreau, Sandra V. Jeffers, Stephen Mar… 展开作者

Kai Ikuta, Kosuke Namekata, Pascal Petit, Vladimir S. Airapetian, Hiroyuki Maehara, Yuta Notsu, Aline A. Vidotto, Keith Gendreau, Sandra V. Jeffers, Stephen Marsden, Julien Morin, Coralie Neiner, Rishi R. Paudel, Daisaku Nogami, Kazunari Shibata

备注：
26 pages, 9 figures, 7 tables, accepted for publication in ApJ
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AI总结：

本研究通过多波段观测分析EK Dra的星斑与磁场关系，揭示了日冕喷射与超闪焰的关联，并量化了活跃恒星的XUV辐射对系外行星大气演化的意义。

摘要：

最近对附近年轻太阳型恒星EK Dra的光学、Hα光谱和X射线的同步多波段观测提供了证据，表明与超闪焰相关的恒星日冕喷射。大型日冕喷射被认为是由TESS同时进行的Zeeman Doppler成像（ZDI）和光学光度计在恒星边缘附近极性反转线上的大中纬度斑中引起的。在本研究中，我们对TESS数据进行星斑映射，以研究光度计和ZDI中的星斑与磁场的关系。我们还探讨了TESS、B波段、Hα和X射线光变曲线中归因于星斑和活跃区域的多波段旋转变异性。结果发现，（i）从TESS光变曲线推导出的斑点位置与ZDI的强度图基本一致，除了极区斑点外；（ii）Hα光变曲线相对于TESS光变曲线表现出明显的周期性，因为Hα线在色球中围绕斑点辐射。X射线光变曲线不显示这种关联，可能是因为高活动水平上的多个斑点和日冕活跃区域的扩展空间结构。这些结果为探索不同高度活跃区域在色球和日冕线中的关联提供了线索。我们的研究还使我们能够通过活跃恒星的磁场量化恒星XUV辐射，以理解系外行星的大气演化。

英文摘要：

Recent simultaneous multiwavelength observations of a nearby young solar-type star EK Dra in the optical, H$α$ spectrum, and X-ray, have provided evidence for stellar prominence eruptions associated with superflares. The large prominence eruption is suggested to have been caused by a large mid-latitude spot on the polarity inversion lines near the stellar limb from the concurrent Zeeman Doppler Imaging (ZDI) and optical photometry by the TESS. In this study, we perform starspot mapping for the TESS data of EK Dra to investigate the relation of starspots and magnetic fields from the photometry and ZDI. We also explore the multiwavelength rotational variability ascribed to starspots and active regions for the TESS, B-band, H$α$, and X-ray light curves. As a result, we find that (i) spot locations deduced from the TESS light curve are mostly consistent with the intensity map from the ZDI except for a polar spot, and (ii) the H$α$ light curve exhibits clear periodicity with respect to the TESS light curve because the H$α$ line is radiated around spots in the chromosphere. The X-ray light curve does not show such association probably because of multiple spots on high activity level and extended spatial structure of coronal active regions. The results provide clues to explore their association with stellar flares at different heights of active regions in chromospheric and coronal lines. Our study also enables us to quantify the stellar XUV radiation from the magnetic fields of active stars toward understanding atmospheric evolution of exoplanets.

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