标题： 模拟恒星日冕物质抛射的巴尔末线特征 显示英文标题

标题： Modeling Balmer line signatures of stellar CMEs

摘要： 从太阳我们知道，日冕物质抛射（CMEs）是一种瞬态现象，通常与耀斑相关。它们对太阳的质量和角动量损失有影响，因此对太阳演化有影响，并且是空间天气的重要组成部分。对于恒星来说也是如此，但恒星CMEs仍然没有得到很好的约束，尽管已经建立了新的方法，并在最近提出了新的检测结果。到目前为止，已经提出了可能的恒星CME检测，但其物理参数，如电子密度、光学厚度、温度等，这些参数无法直接从观测中获得，大多数已知事件尚未确定。我们应用云模型，像在太阳上常用的那样，对文献中已知的一个事件进行研究，该事件是在年轻的dMe星V374 Peg上检测到的。这个事件表现为巴尔末线蓝侧的额外发射。通过从1D非局部热平衡建模中确定线源函数，并结合云模型公式，我们给出了该事件的物理参数分布。我们发现除了温度和面积外，所有参数都处于典型太阳日珥参数的上限范围。该事件的温度和面积被发现高于在巴尔末线中观测到的典型太阳日珥。我们发现比日珥几何结构更多的解用于丝状体。此外，我们表明丝状体可以在dMe星上以发射形式出现，这与太阳的情况相反。 显示英文摘要

摘要： From the Sun we know that coronal mass ejections (CMEs) are a transient phenomenon, often correlated with flares. They have an impact on solar mass- and angular momentum loss, and therefore solar evolution, and make a significant part of space weather. The same is true for stars, but stellar CMEs are still not well constrained, although new methodologies have been established, and new detections presented in the recent past. So far, probable detections of stellar CMEs have been presented, but their physical parameters which are not directly accessible from observations, such as electron density, optical thickness, temperature, etc., have been so far not determined for the majority of known events. We apply cloud modeling, as commonly used on the Sun, to a known event from the literature, detected on the young dMe star V374 Peg. This event manifests itself in extra emission on the blue side of the Balmer lines. By determining the line source function from 1D NLTE modeling together with the cloud model formulation we present distributions of physical parameters of this event. We find that except for temperature and area all parameters are at the upper range of typical solar prominence parameters. The temperature and the area of the event were found to be higher than for typical solar prominences observed in Balmer lines. We find more solutions for the filament than for the prominence geometry. Moreover we show that filaments can appear in emission on dMe stars contrary to the solar case.