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arXiv 2102.07875astro-ph.SR
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通过模拟和射电资料的比较追踪太阳型II爆发的来源

Tracking the Source of Solar Type II Bursts through Comparisons of Simulations and Radio Data

Alexander M. Hegedus, Ward B. Manchester, Justin C. Kasper

摘要:

最强烈的太阳高能粒子事件是由日冕物质抛射(CME)伴随着15 MHz以下的强烈II型射电爆发产生的。了解这些II型爆发相对于爆发的CME产生的位置将揭示太阳附近粒子加速的重要细节,但由于电离层的扭曲,无法在地球上成像。在这里,介绍了一种技术,以确定可能的源位置的排放比较观察到的动态光谱从一个单一的航天器对合成光谱内的磁流体动力学(MHD)数值模拟的重建日冕物质抛射的假设发射区域。无线电响亮2005年5月13日CME被选为一个测试案例,风/波无线电数据用于框架的逆问题,找到最有可能的进展的突发位置。一个MHD的重建是用来创建各种假设的突发位置的合成光谱。开发了一个框架来评分这些合成光谱的相似性II型频率分布来自风/波数据。模拟领域与4倍增强熵和提高德霍夫曼泰勒速度被发现产生合成光谱类似于航天器观测。几何分析表明,在日心坐标系中,熵衍生激波的东部边缘在(-30,0)度附近,在事件发生的第一个小时内发射,然后停止发射,而在以(6,-12)度为中心的激波的西部/西南边缘是20个太阳半径的2小时模拟数据的无线电发射的主要区域。

英文摘要:

The most intense solar energetic particle events are produced by coronal mass ejections (CMEs) accompanied by intense type II radio bursts below 15 MHz. Understanding where these type II bursts are generated relative to an erupting CME would reveal important details of particle acceleration near the Sun, but the emission cannot be imaged on Earth due to distortion from its ionosphere. Here, a technique is introduced to identify the likely source location of the emission by comparing the observed dynamic spectrum observed from a single spacecraft against synthetic spectra made from hypothesized emitting regions within a magnetohydrodynamic (MHD) numerical simulation of the recreated CME. The radio-loud 2005 May 13 CME was chosen as a test case, with Wind/WAVES radio data used to frame the inverse problem of finding the most likely progression of burst locations. An MHD recreation is used to create synthetic spectra for various hypothesized burst locations. A framework is developed to score these synthetic spectra by their similarity to the type II frequency profile derived from Wind/WAVES data. Simulated areas with 4x enhanced entropy and elevated de Hoffmann Teller velocities are found to produce synthetic spectra similar to spacecraft observations. A geometrical analysis suggests that the eastern edge of the entropy derived shock around (-30, 0) degrees in heliocentric coordinates was emitting in the first hour of the event before ceasing emission, and that the western/southwestern edge of the shock centered around (6, -12) degrees was a dominant area of radio emission for the 2 hours of simulation data out to 20 solar radii.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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