Investigating the rotational phase of stellar flares on M dwarfs using K2 short cadence data
Investigating the rotational phase of stellar flares on M dwarfs using K2 short cadence data
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DOI：
10.1093/mnras/sty1963
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发表时间：
2018-07
影响因子：
4.8
通讯作者：
L.Doyle;G. Ramsay;J. Doyle;K. Wu;E. Scullion
中科院分区：
文献类型：
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作者：
L.Doyle;G. Ramsay;J. Doyle;K. Wu;E. Scullion
我们提出了一个分析的K2短节奏数据的34个M矮星的光谱类型的范围M0-L1。在这些恒星中，有31颗出现了持续时间在10 - 90分钟之间的耀斑。利用从盖亚DR 2耀斑获得的距离，我们确定耀斑的能量范围为1.2 × 10^29-6 × 10^34尔格。与以前的研究一致，我们发现快速旋转的恒星往往会显示出更多的耀斑，有证据表明旋转周期超过100天的恒星活动会下降。在M矮星中看到的旋转调制被广泛认为是由一个在视野中旋转和旋转的恒星黑子引起的。因此，通量最小值是我们看到靠近恒星盘中心的主恒星黑子的旋转阶段。令人惊讶的是，在我们的研究中确定了每个耀斑的旋转相位后，我们发现没有一个耀斑显示出对旋转相位的偏好。我们概述了三种情况，可以解释这一意外的发现。旋转相位和耀斑速率之间的关系将进一步探讨使用的数据，从广泛的调查，如NGTS和TESS。
We present an analysis of K2 short cadence data of 34 M dwarfs which have spectral types in the range M0-L1. Of these stars, 31 showed flares with a duration between ˜10 and 90min. Using distances obtained from Gaia DR2 parallaxes, we determined the energy of the flares to be in the range ˜1.2 × 10^29-6 × 10^34 erg. In agreement with previous studies we find rapidly rotating stars tend to show more flares, with evidence for a decline in activity in stars with rotation periods longer than ˜10 d. The rotational modulation seen in M dwarf stars is widely considered to result from a starspot which rotates in and out of view. Flux minimum is therefore the rotation phase where we view the main starspot close to the stellar disc centre. Surprisingly, having determined the rotational phase of each flare in our study we find none show any preference for rotational phase. We outline three scenarios which could account for this unexpected finding. The relationship between rotation phase and flare rate will be explored further using data from wide surveys such as NGTS and TESS.