Modeling Balmer line signatures of stellar CMEs
Modeling Balmer line signatures of stellar CMEs
复制标题
恒星日冕物质抛射的巴尔默线特征建模
DOI：
10.1093/mnras/stac1284
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发表时间：
2022
影响因子：
4.8
通讯作者：
P. Heinzel
中科院分区：
文献类型：
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作者：
M. Leitzinger;P. Odert;P. Heinzel
从太阳我们知道日冕物质抛射（CME）是一种瞬态现象，通常与耀斑相关。它们对太阳质量和角动量损失产生影响，从而影响太阳演化，并成为太空天气的重要组成部分。对于恒星来说也是如此，但恒星日冕物质抛射仍然没有得到很好的约束，尽管已经建立了新的方法，并且最近提出了新的探测结果。到目前为止，恒星日冕物质抛射的可能探测结果已经提出，但大多数已知事件的电子密度、光学厚度、温度等无法直接从观测中获得的物理参数尚未确定。我们将太阳上常用的云模型应用于文献中已知的事件，该事件是在年轻的 dMe 恒星 V374 Peg 上检测到的。这一事件表现为巴尔默线蓝色一侧的额外发射。通过从 1D NLTE 建模中确定线源函数以及云模型公式，我们给出了该事件的物理参数的分布。我们发现，除了温度和面积之外，所有参数都处于典型日珥参数的上限。发现该事件的温度和面积高于巴尔默线观测到的典型日珥。我们为细丝找到了比突出几何形状更多的解决方案。此外，我们还表明，与太阳的情况相反，dMe 恒星的发射中可能会出现细丝。
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.