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arXiv 2203.01043astro-ph.SRastro-ph.HE
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首次探测到来自太阳激增的公制发射

First detection of metric emission from a solar surge

C. E. Alissandrakis, S. Patsourakos, A. Nindos, C. Bouratzis, A. Hillaris

摘要:

我们报告的第一次检测到米制无线电发射的激增,观察与Nançay射电日像仪(NRH),立体声和其他仪器。在M9复合事件SOL 2010 -02- 012 T11:25:00的晚期观察到发射,如先前出版物所述,与二次能量释放相关,也在STEREO 304 SPECT图像中观察到:未检测到软X射线发射。立体图像的三角测量允许识别中央子午线附近的NRH源的浪涌。浪涌的无线电发射分两个阶段发生,由两个来源组成,一个位于浪涌底部附近,显然是在能量释放的位置或附近,另一个位于浪涌的上部;这些在445.0至约300 MHz的频率范围内最清晰可见,而在较低频率处观察到不同性质的频谱成分。在这两个阶段,在两个源中都检测到了亚秒级的时间变化,上源相对于下源的延迟为0.2- 0.3秒,这表明超光速。如果上层源的发射是由于浪涌底部源的辐射散射,则可以解释这种效应。此外,无线电发射显示出脉动和尖峰的迹象。我们讨论了低射电源的慢时变分量可能的发射机制。回旋同步辐射相当好地再现了在事件的第二阶段开始时观察到的总强度谱的特征,但未能再现观察到的高程度的圆偏振以及在其他情况下的谱。另一方面,类IV等离子体发射的基本可以解释高极化和精细结构的动态频谱;此外,它给出了投影射电源的位置在天空的平面上,从STEREO-A,附近的基地激增。考虑到一切,我们建议IV型等离子体发射与低强度的回旋同步加速器组件作为最合理的机制。

英文摘要:

We report the first detection of metric radio emission from a surge, observed with the Nançay Radioheliograph (NRH), STEREO and other instruments. The emission was observed during the late phase of the M9 complex event SOL2010-02-012T11:25:00, described in a previous publication and was associated with a secondary energy release, also observed in STEREO 304 Å images: there was no detectable soft X-ray emission. Triangulation of the STEREO images allowed the identification of the surge with NRH sources near the central meridian. The radio emission of the surge occurred in two phases and consisted of two sources, one located near the base of the surge, apparently at or near the site of energy release, and another in the upper part of the surge; these were best visible in the frequency range of 445.0 to about 300MHz, whereas a spectral component of different nature was observed at lower frequencies. Sub-second time variations were detected in both sources during both phases, with 0.2-0.3s a delay of the upper source with respect to the lower, suggesting superluminal velocities. This effect can be explained if the emission of the upper source was due to scattering of radiation from the source at the base of the surge. In addition, the radio emission showed signs of pulsations and spikes. We discuss possible emission mechanisms for the slow time variability component of the lower radio source. Gyrosynchrotron emission reproduced fairly well the characteristics of the observed total intensity spectrum at the start of the second phase of the event, but failed to reproduce the high degree of the observed circular polarization as well the spectra at other instances. On the other hand, type IV-like plasma emission from the fundamental could explain the high polarization and the fine structure in the dynamic spectrum; moreover, it gives projected radio source positions on the plane of the sky, as seen from STEREO-A, near the base of the surge. Taking everything into consideration, we suggest type IV-like plasma emission with a low intensity gyrosynchrotron component as the most plausible mechanism.

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