Periodicities in an active region correlated with Type III radio bursts observed by Parker Solar Probe.
Periodicities in an active region correlated with Type III radio bursts observed by Parker Solar Probe.
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DOI：
10.1051/0004-6361/202039510
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发表时间：
2021-06
影响因子：
6.5
通讯作者：
Bale SD
中科院分区：
文献类型：
--
作者：
Cattell C;Glesener L;Leiran B;Dombeck J;Goetz K;Martínez Oliveros JC;Badman ST;Pulupa M;Bale SD
在日冕的许多波长上都经常有周期性的报道。~5分钟的相关周期（与太阳p模式相当）表明光球和日冕之间存在耦合。我们的研究调查是否有相关性的周期性行为的III型射电暴，这是指示非热电子加速过程，和日冕极紫外线（EUV）的排放，用于评估加热和冷却的活动区域时，没有大的耀斑。我们使用了帕克太阳探测器（PSP）上的FIELDS仪器的III型射电爆发的协调观测，太阳动力学天文台（SDO）大气成像组件（AIA）的EUV发射和SDO日震和磁性图像（HMI）的白色光观测，以及2019年4月12日核光谱望远镜阵列（努斯塔）的太阳耀斑X射线。利用几种方法来评估周期性和比较，以验证所获得的周期。在活动区的几个地区的EUV中的~5分钟的周期性与PSP和Wind上观察到的III型射电爆发的重复率有很好的相关性。去除趋势的211和171光变曲线在多个位置显示出周期性的轮廓，171峰有时会滞后于211峰。这暗示了导致下部日冕加热然后冷却的脉冲事件。努斯塔X射线提供了在III型爆发间隔期间至少一次微耀斑的证据，但X射线和III型爆发之间没有一一对应的关系。我们的研究提供了非热电子（产生III型射电暴所需的）周期性加速的证据，当在X射线数据或EUV中没有可观察到的耀斑时。因此，加速过程必须与小的脉冲事件相关联，也许是纳米火花。
Periodicities have frequently been reported across many wavelengths in the solar corona. Correlated periods of ~5 min, comparable to solar p-modes, are suggestive of coupling between the photosphere and the corona. Our study investigates whether there are correlations in the periodic behavior of Type III radio bursts which are indicative of nonthermal electron acceleration processes, and coronal extreme ultraviolet (EUV) emission used to assess heating and cooling in an active region when there are no large flares. We used coordinated observations of Type III radio bursts from the FIELDS instrument on Parker Solar Probe (PSP), of EUV emissions by the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) and white light observations by SDO Helioseismic and Magnetic Image (HMI), and of solar flare X-rays by Nuclear Spectroscopic Telescope Array (NuSTAR) on April 12, 2019. Several methods for assessing periodicities are utilized and compared to validate periods obtained. Periodicities of ~5 min in the EUV in several areas of an active region are well correlated with the repetition rate of the Type III radio bursts observed on both PSP and Wind. Detrended 211 and 171 Å light curves show periodic profiles in multiple locations, with 171 Å peaks sometimes lagging those seen in 211 Å. This is suggestive of impulsive events that result in heating and then cooling in the lower corona. NuSTAR X-rays provide evidence for at least one microflare during the interval of Type III bursts, but there is not a one-to-one correspondence between the X-rays and the Type III bursts. Our study provides evidence for periodic acceleration of nonthermal electrons (required to generate Type III radio bursts) when there were no observable flares either in the X-ray data or the EUV. The acceleration process, therefore, must be associated with small impulsive events, perhaps nanoflares.