Abstract

The detection of radio emission from solar flares at frequencies below \({\sim}2\) GHz allows the upper limits for the characteristic size of the soft X-ray (SXR) source \(L(t)\) to be estimated under the assumption that the density \(n(t)\) is determined by the plasma frequency \(\nu_{p}\). If the SXR source with a higher density is inside the radio source, then the size of the SXR source will be \(L(t)<(EM(t)/2n(t)^{2})^{1/3}\), where \(EM(t)\) is the emission measure. For three flares (C7.2 on December 22, 2009, M2.9 on July 6, 2012, and X1.1 on July 6, 2012) we calculate the expansion speeds of the SXR source \(V(t)\sim dL(t)/dt\), which are compared with the estimates of the sound speed and the Alfvén speed. By ‘‘magnetic detonation’’ we mean the process of the propagation of magnetic reconnection with a supersonic speed in eruptive flares. Magnetic detonation and the succeeding coronal mass ejection (CME) were realized in the December 22, 2009 C7.2 and July 6, 2012 X1.1 flares, in which supersonic and super-Alfvén speeds were reached if the density of the SXR source was lower than \(2.1\times 10^{9}\) and \(7.4\times 10^{8}\) cm\({}^{-3}\) (\(\nu_{p}<410\) and \({<}245\) MHz), respectively. There were no magnetic detonation and CME in the July 6, 2012 M2.9 flare, whose radio emission frequencies were only above 1415 MHz (\(n>2.5\times 10^{10}\) cm\({}^{-3}\)). For magnetic detonation in the July 6, 2012 X1.1 flare we have estimated the magnetic field strength, the reconnection electric field strength, the plasma flow, and the CME mass.

中文翻译：

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软 X 射线源的扩展和太阳耀斑中的“磁爆”

摘要

通过检测频率低于\({\sim}2\) GHz 的太阳耀斑无线电发射，可以估计软 X 射线 (SXR) 源\(L(t)\)特征尺寸的上限假设密度\(n(t)\)由等离子体频率\(\nu_{p}\)确定。如果密度较高的 SXR 源位于射电源内部，则 SXR 源的大小将为\(L(t)<(EM(t)/2n(t)^{2})^{1/3 }\)，其中\(EM(t)\)是排放量。对于三个耀斑（2009年12月22日的C7.2、2012年7月6日的M2.9和2012年7月6日的X1.1），我们计算SXR源的膨胀速度\( V(t)\sim dL (t)/dt\)，与声速和阿尔文速度的估计值进行比较。我们所说的“磁爆”是指在喷发耀斑中以超音速传播磁重联的过程。磁爆和随后的日冕物质抛射 (CME) 在 2009 年 12 月 22 日的 C7.2 和 2012 年 7 月 6 日的 X1.1 耀斑中实现，其中如果 SXR 源的密度为低于\(2.1\times 10^{9}\)和\(7.4\times 10^{8}\) cm \({}^{-3}\) ( \(\nu_{p}<410\) )和\({<}245\) MHz) 分别。2012年7月6日的M2.9耀斑没有发生磁爆和日冕物质抛射，其无线电发射频率仅在1415 MHz以上 ( \(n>2.5\times 10^{10}\) cm \({}^{- 3}\)）。对于 2012 年 7 月 6 日 X1.1 耀斑中的磁爆，我们估计了磁场强度、重联电场强度、等离子体流和 CME 质量。