Starspot Activity and Superflares on Solar-type Stars
Starspot Activity and Superflares on Solar-type Stars
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DOI：
10.1093/pasj/psx013
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发表时间：
2016-10
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影响因子：
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通讯作者：
H. Maehara
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作者：
H. Maehara
最近从太空(如开普勒)进行的高精度测光使我们能够研究太阳类型恒星上的“超耀斑”的性质。开普勒探测到的超耀斑的辐射热能范围为1033-1036 erg，是典型的X10级耀斑辐射能量的10-10000倍。超耀斑的发生频率(dN/de)与耀斑能量(E)呈幂函数关系，其幂指数为~−.8。大多数超耀星表现出准周期的光变化，这表明存在大的恒星黑子。耀斑释放的测辐射能与储存在恒星黑子附近的磁能是一致的。超耀斑的发生频率随着自转周期的减小而增加。然而，在给定的周期内观测到的最大耀斑的能量与自转周期并没有显示出任何明显的相关性。这些结果表明，在缓慢自转的恒星上会出现超耀斑。
Abstract Recent high-precision photometry from space (e.g., Kepler) enables us to investigate the nature of “superflares” on solar-type stars. The bolometric energy of superflares detected by Kepler ranges from 1033 erg to 1036 erg which is 10-10,000 times larger than that released by a typical X10 class solar flare. The occurrence frequency (dN/dE) of superflares as a function of flare energy (E) shows the power-law distribution with the power-law index of ~−1.8 for 1034 < E < 1036 erg. Most of superflare stars show quasi-periodic light variations which suggest the presence of large starspots. The bolometric energy released by flares is consistent with the magnetic energy stored near the starspots. The occurrence frequency of superflares increases as the rotation period decreases. However, the energy of the largest flares observed in a given period bin does not show any clear correlation with the rotation period. These results suggest that superflares would occur on the slowly-rotating stars.