The Stellar CME–Flare Relation: What Do Historic Observations Reveal?
The Stellar CME–Flare Relation: What Do Historic Observations Reveal?
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DOI：
10.3847/1538-4357/ab1b37
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发表时间：
2019-04
期刊：
影响因子：
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通讯作者：
S. Moschou;J. Drake;O. Cohen;J. D. Alvarado-G'omez;C. Garraffo;F. Fraschetti
中科院分区：
文献类型：
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作者：
S. Moschou;J. Drake;O. Cohen;J. D. Alvarado-G'omez;C. Garraffo;F. Fraschetti
太阳日冕物质抛射（CME）和耀斑有一个统计上明确定义的关系，更高能量的X射线耀斑对应更快，更大质量的CME。这种关系如何延伸到磁活跃的恒星是一个开放的研究课题。在这里，我们研究最有可能的恒星CME候选人与耀斑在文献中捕获的日期，所有这些都被观察到的磁性活跃的恒星。我们使用一个简单的CME模型，从观测到的数量和转换相关的耀斑数据的地球同步业务环境卫星1-8毫米波段的质量和动能。CME的质量范围从1015到1022克。相关的耀斑X射线能量范围从1031到1037 erg。恒星日冕物质抛射的质量作为耀斑能量的函数，通常沿着或低于太阳事件的外推平均值。相比之下，CME动能低于类似的太阳外推大约2个数量级，表明耀斑X射线和CME动能之间的近似平价。这些结果表明，CME与非常活跃的恒星上的能量耀斑更有限的喷出物的速度比喷出物的质量，可能是因为强烈的叠加磁场和恒星风阻力的抑制影响。较低的CME动能和速度为CME对靠近活跃恒星宿主的系外行星的影响提供了更乐观的情况。
Solar coronal mass ejections (CMEs) and flares have a statistically well-defined relationship, with more energetic X-ray flares corresponding to faster and more massive CMEs. How this relationship extends to more magnetically active stars is a subject of open research. Here we study the most probable stellar CME candidates associated with flares captured in the literature to date, all of which were observed on magnetically active stars. We use a simple CME model to derive masses and kinetic energies from observed quantities and transform associated flare data to the Geostationary Operational Environmental Satellite 1–8 Å band. Derived CME masses range from ∼1015 to 1022 g. Associated flare X-ray energies range from 1031 to 1037 erg. Stellar CME masses as a function of associated flare energy generally lie along or below the extrapolated mean for solar events. In contrast, CME kinetic energies lie below the analogous solar extrapolation by roughly 2 orders of magnitude, indicating approximate parity between flare X-ray and CME kinetic energies. These results suggest that the CMEs associated with very energetic flares on active stars are more limited in terms of the ejecta velocity than the ejecta mass, possibly because of the restraining influence of strong overlying magnetic fields and stellar wind drag. Lower CME kinetic energies and velocities present a more optimistic scenario for the effects of CME impacts on exoplanets in close proximity to active stellar hosts.