OBSERVATION OF A METRIC TYPE N SOLAR RADIO BURST

被引:10
作者
Kong, Xiangliang [1 ,2 ]
Chen, Yao [1 ,2 ]
Feng, Shiwei [1 ,2 ]
Du, Guohui [1 ,2 ]
Li, Chuanyang [1 ,2 ]
Koval, Artem [1 ,2 ,3 ]
Vasanth, V. [1 ,2 ]
Wang, Bing [1 ,2 ]
Guo, Fan [4 ]
Li, Gang [5 ,6 ]
机构
[1] Shandong Univ, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai 264209, Shandong, Peoples R China
[2] Shandong Univ, Inst Space Sci, Weihai 264209, Shandong, Peoples R China
[3] Natl Acad Sci Ukraine, Inst Radio Astron, UA-61002 Kharkov, Ukraine
[4] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA
[5] Univ Alabama, Dept Space Sci, Huntsville, AL 35899 USA
[6] Univ Alabama, CSPAR, Huntsville, AL 35899 USA
基金
美国国家科学基金会;
关键词
Sun: corona; Sun: flares; Sun: magnetic fields; Sun: radio radiation; ELECTRON-BEAMS; PARTICLE-ACCELERATION; HARMONIC EMISSION; U-BURSTS; POLARIZATION; PLASMA; INTERPLANETARY; CORONA; MODEL; SUN;
D O I
10.3847/0004-637X/830/1/37
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Type III and type-III-like radio bursts are produced by energetic electron beams guided along coronal magnetic fields. As a variant of type III bursts, Type N bursts appear as the letter "N" in the radio dynamic spectrum and reveal a magnetic mirror effect in coronal loops. Here, we report a well-observed N-shaped burst consisting of three successive branches at metric wavelength with both fundamental and harmonic components and a high brightness temperature (>10(9) K). We verify the burst as a true type N burst generated by the same electron beam from three aspects of the data. First, durations of the three branches at a given frequency increase gradually and. may be. due to the dispersion of the beam along its path. Second, the flare site, as the only possible source of non-thermal electrons, is near the western feet of large-scale closed loops. Third, the first branch and the following two branches are localized at different legs of the loops with opposite senses of. polarization. We also find that the sense of polarization of the radio burst is in contradiction to the O-mode and there exists a fairly large time delay (similar to 3-5 s) between the fundamental and harmonic components. Possible explanations accounting for these observations are presented. Assuming the classical plasma emission mechanism, we can infer coronal parameters such as electron density and magnetic field near the radio source and make diagnostics on the magnetic mirror process.
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页数:7
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