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Local sunspot oscillations and umbral dots

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Research in Astronomy and Astrophysics 2018年第9期18卷 1-12页

作者： Yuzef Zhugzhda robert sych IZMIRAN Institute of Solar-Terrestrial Physics SB RAN Irkutsk Russia

Data analysis of sunspot oscillations based on a 6-hr SDO run of an observation showed that low frequency （0.2 〈ω 〈 1 mHz） oscillations are locally similar to three and five minute oscillations. The oscillations in the sunspot are concentrated in cells of a few arcsec, each of which has its own oscillation spectrum. The analysis of two scenarios for sunspot oscillations leads to a conclusion that local sunspot oscillations occur due to a subphotospheric resonator for slow MHD waves. Empirical models of a sunspot atmosphere and the theory of slow waves in thin magnetic flux tubes are applied to modeling the subphotospheric resonator. The spectrum of local oscillations consists of a great number of lines. This kind of spectrum can occur only if the subphotospheric resonator is a magnetic tube with a rather weak magnetic field. Magnetic tubes of this sort are umbral dots that appear due to the convective tongues in monolithic sunspots. The interrelation of local oscillations with umbral dots and wavefronts of traveling waves in sunspots is discussed.

关键词： Sun sunspot - methods numerical - waves

Magneto-acoustic waves in magnetic twisted flux tubes

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Research in Astronomy and Astrophysics 2021年第5期21卷 247-254页

作者： Wei Wu robert sych Jie Chen Jiang-Tao Su School of Astronomy and Space Sciences University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Institute of Solar-Terrestrial Physics SB RAS Irkutsk 664033Russia

At present,many works about MHD wave diagnostics in magnetic flux tubes are based on some pioneering works not considering the contributions of magnetic *** works considered the effect on MHD waves,but the dispersion relationship they presented only gave the wave modes of m=0,1,2...The kink mode of m=−1 was ***,in this work we present a complete dispersion relationship that includes both magnetic twist and the wave mode of m=−*** to the m=+1 wave mode,the mode of m=−1 also exhibits the mode change at finite kr0,from body to surface *** phase speeds of this mode are usually less than those of m=+1 *** harmonic curves of m=±1 modes in dispersion relationship diagrams are approximately symmetric in respect to a characteristic velocity,*** tube velocity in flux *** on the present dispersion relationship,we revisit the issue of spiral wave patterns in sunspots and find that the magnetic twist has no great influence on their morphology in the frame of linear perturbation analysis.

关键词： Sun:sunspots Sun:oscillations Sun:atmosphere

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