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Recent results of zebra patterns in solar radio bursts

Research in Astronomy and Astrophysics 2010年第9期10卷 821-866页

作者： gennady p.chernov Key Laboratory of Solar Activity National Astronomical ObservatoryChinese Academy of Science pushkov Institute of Terrestrial Magnetism Ionosphere and Radio Wave PropagationRussian Academy of Sciences (IZMIRAN)

This review covers the most recent experimental results and theoretical research on zebra patterns （Zps） in solar radio bursts. The basic attention is given to events with new peculiar elements of zebra patterns received over the last few years. All new properties are considered in light of both what was known earlier and new theoretical models. Large-scale Zps consisting of small-scale fiber bursts could be explained by simultaneous inclusion of two mechanisms when whistler waves ＂high- light＂ the levels of double plasma resonance （DpR）. A unique fine structure was observed in the event on 2006 December 13： spikes in absorption formed dark Zp stripes against the absorptive type Ⅲ-like bursts. The spikes in absorption can appear in accordance with well known mechanisms of absorptive bursts. The additional injection of fast particles filled the loss-cone （breaking the loss-cone distribution）, and the generation of the continuum was quenched at these moments. The maximum absorptive effect occurs at the DpR levels. The parameters of millisecond spikes are determined by small dimensions of the particle beams and local scale heights in the radio source. Thus, the DpR model helps to understand severai aspects of unusual elements of Zps. However, the simultaneous existence of several tens of the DpR levels in the corona is impossible for any realistic profile of the plasma density and magnetic field. Three new theories of Zps are examined. The formation of eigenmodes of transparency and opac- ity during the propagation of radio waves through regular coronal inhomogeneities is the most natural and promising mechanism. Two other models （nonlinear periodic space - charge waves and scattering of fast protons on ion-sound harmonics） could happen in large radio bursts.

关键词： Sun general -- Sun flare -- Sun radio radiation

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Concerning spikes in emission and absorption in the microwave range

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Research in Astronomy and Astrophysics 2013年第1期13卷 115-128页

作者： gennady p.chernov Robert A.Sych Guang-Li Huang Hai-Sheng Ji Yi-Hua Yan Cheng-Ming Tan Key Laboratory of Solar Activity National Astronomical ObservatoryChinese Academy of Sciences pushkov Institute of Terrestrial Magnetism Ionosphere and Radio Wave PropagationRussian Academy of Sciences (IZMIRAN) Institute of Solar-Terrestrial physics purple Mountain Observatory Chinese Academy of Sciences

In some events, weak fast solar bursts （near the level of the quiet Sun） were observed in the background of numerous spikes in emission and absorption. In such a case, the background contains the noise signals of the receiver. In events on 2005 September 16 and 2002 April 14, the solar origin of fast bursts was confirmed by simultaneous recording of the bursts at several remote observatories. The noisy background pixels in emission and absorption can be excluded by subtracting a higher level of continuum when constructing the spectra. The wavelet spectrum, noisy pro- files in different polarization channels and a spectrum with continuum level greater than zero demonstrates the noisy character of pixels with the lowest levels of emission and absorption. Thus, in each case, in order to judge the solar origin of all spikes, it is necessary to determine the level of continuum against the background of which the solar bursts are observed. Several models of microwave spikes are discussed. The electron cyclotron maser emission mechanism runs into serious problems with the in- terpretation of microwave millisecond spikes： the main obstacles are too high values of the magnetic field strength in the source （pe 〈 uB）. The probable mechanism is the interaction of plasma Langmuir waves with ion-sound waves （l ＋ s → t） in a source related to shock fronts in the reconnection region.

关键词： solar flare -- radio emission -- spike-bursts

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Flare evolution and polarization changes in fine structures of solar radio emission in the 2013 April 11 event

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Research in Astronomy and Astrophysics 2016年第2期16卷 69-80页

作者： gennady chernov Robert Sych Bao-Lin Tan Yi-Hua Yan Cheng-Ming Tan Qi-Jun Fu Marian Karlicky Valery Fomichev Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China pushkov Institute of Terrestrial Magnetism Ionosphere and Radio Wave PropagationRussian Academy of Sciences(IZMIRAN)TroitskMoscow region142190Russia Yunnan Observatories Chinese Academy of SciencesKunming 650011China Institute of Solar-Terrestrial physics Russian Academy of SciencesSiberian BranchIrkutsk 664033Russia Astronomical Institute of the Academy of Sciences of the Czech Republic Ondrejov 15165Czech Republic

The measurement of positions and sizes of radio sources in observations is important for un- derstanding of the flare evolution. For the first time, solar radio spectral fine structures in an M6.5 flare that occurred on 2013 April 11 were observed simultaneously by several radio instruments at four different observatories： Chinese Solar Broadband Radio Spectrometer at Huairou （SBRS/Huairou）, Ondrejov Radio Spectrograph in the Czech Republic （ORSC/Ondrejov）, Badary Broadband Microwave Spectropolarimeter （BMS/Irkutsk）, and spectrograph/IZMIRAN （Moscow, Troitsk）. The fine structures included microwave zebra patterns （Zps）, fast pulsations and fiber bursts. They were observed during the flare brightening lo- cated at the tops of a loop arcade as shown in images taken by the extreme ultraviolet （EUV） telescope onboard NASA＇s satellite Solar Dynamics Observatory （SDO）. The flare occurred at 06：58-07：26 UT in solar active region NOAA 11719 located close to the solar disk center. Zps appeared near high frequency boundaries of the pulsations, and their spectra observed in Huairou and Ondrejov agreed with each other in terms of details. At the beginning of the flare＇s impulsive phase, a strong narrowband Zp burst occurred with a moderate left-handed circular polarization. Then a series of pulsations and Zps were observed in almost unpolarized emission. After 07：00 UT a Zp appeared with a moderate right-handed polarization. In the flare decay phase （at about 07：25 UT）, Zps and fiber bursts become strongly right-hand polarized. BMS/Irkutsk spectral observations indicated that the background emission showed a left-handed circular polarization （similar to SBRS/Huairou spectra around 3 GHz）. However, the fine structure appeared in the right-handed polarization. The dynamics of the polarization was associated with the motion of the flare ex- citer, which was observed in EUV images at 171 A and 131 A by the SDO Atmospheric Imaging Assembly （AIA）. Combining magnetograms observed by t

关键词： Sun activity -- Sun flares -- Sun particle emission -- Sun radio radiation -- zebra-pattern

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