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arXiv 2302.00071astro-ph.SRphysics.plasm-ph
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两次连续度规型II射电爆发的日冕密度turbulence和源区磁场强度

Solar coronal density turbulence and magnetic field strength at the source regions of two successive metric type II radio bursts

R. Ramesh, C. Kathiravan, Anshu Kumari

摘要:

我们报告了两个弱的,低频(${\approx}$ 85- 60\,MHz)的太阳日冕II型射电爆发,发生在2020年5月29日的时间间隔${\approx}$ 2\,分钟的光谱和偏振观测。爆发有精细的结构,是由于谐波等离子体发射。我们的分析表明,磁流体动力学(MHD)冲击负责的第一和第二次II型爆发产生的极端紫外(EUV)通量绳/日冕物质抛射(CME)的前缘(LE)和其侧翼与邻近的日冕结构的相互作用,分别。日冕物质抛射在近日日冕中传播过程中,由于${\approx}25^{\arcdeg}$的作用而发生径向偏转。第一次爆发点附近的功率谱密度(PSD)和磁场强度($r{\approx}1.35R_{\odot}$)分别为$\rm {\approx}2{\times}10^{-3}\,W^{2}m$和${\approx}$ 1.8 μ g。在相同的$r$下,第二个脉冲串的相应值为$\rm {\approx}10^{-3}\,W^{2}m$和${\approx}$ 0.9“,G。在两个II型爆发的位置的日冕湍流的显着的空间尺度为${\approx}$ 62\,-\,1\,Mm.我们的结论是,在日冕区域的湍流和磁场强度附近的CME LE比其侧翼附近的相应值更高。这两个参数的推导估计值对应于CME LE及其侧翼的相同$r$,后者的延迟为${\approx}$ 2.min。

英文摘要:

We report spectral and polarimeter observations of two weak, low frequency (${\approx}$85-60\,MHz) solar coronal type II radio bursts that occurred on 2020 May 29 within a time interval ${\approx}$2\,min. The bursts had fine structures, and were due to harmonic plasma emission. Our analysis indicates that the magnetohydrodynamic (MHD) shocks responsible for the 1st and 2nd type II bursts were generated by the leading edge (LE) of an extreme-ultraviolet (EUV) flux rope/coronal mass ejection (CME) and interaction of its flank with a neighbouring coronal structure, respectively. The CME deflected from the radial direction by ${\approx}25^{\arcdeg}$ during propagation in the near-Sun corona. The estimated power spectral density (PSD) and magnetic field strength ($B$) near the location of the 1st burst at heliocentric distance $r{\approx}1.35R_{\odot}$ are $\rm {\approx}2{\times}10^{-3}\,W^{2}m$ and ${\approx}$1.8\,G, respectively. The corresponding values for the 2nd burst at the same $r$ are $\rm {\approx}10^{-3}\,W^{2}m$ and ${\approx}$0.9\,G. The significant spatial scales of the coronal turbulence at the location of the two type II bursts are ${\approx}$62\,-\,1\,Mm. Our conclusions from the present work are that the turbulence and magnetic field strength in the coronal region near the CME LE are higher compared to the corresponding values close to its flank. The derived estimates of the two parameters correspond to the same $r$ for both the CME LE and its flank, with a delay of ${\approx}$2\,min for the latter.

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