测量恒星日冕中的磁场是极其困难的。最近，有人提出利用Fe X 257超导线的磁场感生跃迁（MIT）来测量太阳日冕磁场。我们进行了一系列的全球恒星磁流体动力学模型的正演模拟，探讨这种方法扩展到其他晚型恒星的可能性。我们首先合成了每个恒星模型的几条Fe X线的发射，然后根据MIT理论，利用Fe X 257的强度与其他几条Fe X线的强度比计算了磁场强度。最后，我们将导出的场强与模型中的场强进行了比较，并得出结论，该方法至少可以用于测量表面平均磁通量密度比太阳高一个数量级的恒星冕底的磁场强度。我们的研究表明，需要一个极紫外光谱仪进行日常测量的恒星日冕磁场。
英文摘要：
Measurements of the magnetic field in the stellar coronae are extremely difficult. Recently, it was proposed that the magnetic-field-induced transition (MIT) of the Fe X 257 Å line can be used to measure the coronal magnetic field of the Sun. We performed forward modeling with a series of global stellar magnetohydrodynamics models to investigate the possibility of extending this method to other late-type stars. We first synthesized the emissions of several Fe X lines for each stellar model, then calculated the magnetic field strengths using the intensity ratios of Fe X 257 Å to several other Fe X lines based on the MIT theory. Finally, we compared the derived field strengths with those in the models, and concluded that this method can be used to measure at least the magnetic field strengths at the coronal bases of stars with a mean surface magnetic flux density about one order of magnitude higher than that of the Sun. Our investigation suggests the need of an extreme ultraviolet spectrometer to perform routine measurements of the stellar coronal magnetic field.
Variable Winds and Dust Formation in R Coronae Borealis Stars
我们已经观察到的P-天鹅座和不对称，蓝移的吸收轮廓在He I 10830线的12 R Coronae Borealis（RCB）的恒星在短（1个月）和长（3年）的时间尺度，寻找与他们的尘埃形成事件的变化。在几乎所有的情况下，强度和终极速度的线变化显着，并与尘埃形成事件。蓝移速度约400 km/s的强吸收特征出现在可见光亮度下降期间，并在恢复到最大亮度后持续约100天。在下降期和恢复期之外，存在着速度稍低的小余风。这些相关性支持了这样一种模型，即在恒星附近最近形成的尘埃被辐射压力高速向外推动，并将气体一起拖走。
High-Resolution Modelling of Coronae and Winds in Solar-type Stars with Varying Rotation Rates I. X-ray Coronae
Nanjing University（南京大学）；Leibniz Institute for Astrophysics Potsdam（波茨坦阿基米德研究所）；SETI Institute（SETI研究所）；University of Potsdam, Institute of Physics and Astronomy（波茨坦大学物理与天文研究所）；Kyoto University（京都大学）；Aalto University（阿尔托大学）；Max-Planck-Institut für Sonnensystemforschung（马克斯·普朗克太阳系统研究所）；Nordita, KTH Royal Institute of Technology & Stockholm University（北欧理论天体物理学中心，瑞典皇家理工学院与斯德哥尔摩大学）
The Dynamics of Stellar Coronae Harboring Hot-jupiters I. A Time-dependent MHD Simulation of the Interplanetary Environment in the HD 189733 Planetary System
High-Resolution Modelling of Coronae and Winds in Solar-type Stars with Varying Rotation Rates II. Stellar Winds
Nanjing University（南京大学）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（教育部现代天文与天体物理重点实验室（南京大学））；Leibniz Institute for Astrophysics Potsdam（波茨坦莱布尼茨天体物理研究所）；University of Birmingham（伯明翰大学）；Aalto University（阿尔托大学）；Max-Planck-Institut für Sonnensystemforschung（马克斯·普朗克太阳系研究所）；Nordita, KTH Royal Institute of Technology & Stockholm University（诺迪塔，皇家理工学院与斯德哥尔摩大学）
