Effect of Star Rotation Rate on the Characteristics of Energetic Particle Events
Effect of Star Rotation Rate on the Characteristics of Energetic Particle Events
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DOI：
10.3847/2041-8213/ab271d
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发表时间：
2019-06-20
影响因子：
7.9
通讯作者：
Zank, Gary
中科院分区：
文献类型：
--
作者：
Fu, Shuai;Jiang, Yong;Zank, Gary
开普勒使命最近在太阳型恒星上探测到超级耀斑，这提高了它们与高能日冕物质抛射（CME）和高能粒子事件（SEP）有关的可能性。这些空间天气事件可能会影响这些恒星周围系外行星的可居住性。在这里，我们使用改进的粒子加速和传输在日光层（iPATH）模型模拟的时间-强度分布和光谱的SEP加速在CME驱动的冲击从不同年龄的恒星跟踪其旋转速率。我们考虑一个类太阳（G型）星星，有六个不同的旋转速率，从0.5 Ω（圆点）到3.0 Ω（圆点）。在所有六种情况下，一个快速的日冕物质抛射发射类似于1500公里秒（-1）的相同速度，得到的时间-强度分布在三个位置和能量谱在五个位置在1 Au。还示出了作为r的函数的激波阵面处的最大粒子能量。我们的结果表明，在0.8 Au的最大粒子能量在冲击波前的星星的旋转速率增加。然而，事件集成光谱的五个选定的位置沿着CME路径显示复杂的模式。这是因为快速旋转恒星的帕克磁场更加紧密。我们的研究结果可用于估计太阳型恒星周围的类地系外行星的辐射环境。
The recent detection of superflares on solar-type stars by the Kepler mission has raised the possibility that they can be associated with energetic coronal mass ejections (CMEs) and energetic particle events (SEPs). These space weather events can impact the habitability of exoplanets around these stars. Here we use the improved Particle Acceleration and Transport in the Heliosphere (iPATH) model to model the time-intensity profile and spectrum of SEPs accelerated at CME-driven shocks from stars of different ages traced by their rotation rates. We consider a solar-like (G-type) star with six different rotation rates varying from 0.5 Omega(circle dot) to 3.0 Omega(circle dot). In all six cases, a fast CME is launched with the same speed of similar to 1500 km s(-1); the resulting time-intensity profiles at three locations and energy spectra at five locations at 1 au are obtained. The maximum particle energy at the shock front as a function of r is also shown. Our results suggest that within 0.8 au the maximum particle energy at the shock front increases with the rotation rate of the star. However, event-integrated spectra for the five selected locations along the CME path show complicated patterns. This is because the Parker magnetic field for rapidly rotating stars is more tightly winded. Our results can be used in estimating the radiation environments of terrestrial-type exoplanets around solar-type stars.