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Quasi-periodic pulsations with varying period in multi-wavelength observations of an x-class flare  

Jing Huang   Submitted: 2014-08-03 20:53

This work presents an interesting phenomenon of the period variation in quasi-periodic pulsations (QPPs) observed during the impulsive phase of a coronal mass ejection-related X1.1 class flare on 2012 July 6. The period of QPPs was changed from 21 s at soft X-rays (SXR) to 22?23 s at microwaves, to ∼24 s at extreme ultraviolet emissions (EUV), and to 27?32 s at metric?decimetric waves. The microwave, EUV and SXR QPPs, emitted from flare loops of different heights, were oscillating in phase. Fast kink mode oscillations were proposed to be the modulation mechanism, which may exist in a wide region in the solar atmosphere from the chromosphere to the upper corona or even to the interplanetary space. Changed parameters of flare loops through the solar atmosphere could result in the varying period of QPPs at different wavelengths. The first appearing microwave QPPs and quasi-periodic metric-decimetric type III bursts were generated by energetic electrons. This may imply that particle acceleration or magnetic reconnection were located between these two non-thermal emission sources. Thermal QPPs (in SXR and EUV emissions) occurred later than the nonthermal ones, which would suggest a some time for plasma heating or energy dissipation in flare loops during burst processes. At the beginning of flare, a sudden collapse and expansion of two separated flare loop structures occurred simultaneously with the multi-wavelength QPPs. An implosion in the corona, including both collapse and expansion of flare loops, could be a trigger of loop oscillations in a very large region in the solar atmosphere.

Authors: Jing Huang, Baolin Tan, Yin Zhang, Marian Karlickýy, and Hana M?esz?arosov?a
Projects: GOES X-rays ,SDO-AIA,SDO-HMI

Publication Status: published
Last Modified: 2014-08-04 17:58
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Energetic electron propagation in the decay phase of non-thermal flare emission  

Jing Huang   Submitted: 2014-06-12 01:45

On the basis of the trap-plus-precipitation model, the peculiarities of non-thermal emission in the decay phase of solar flares have been considered. The calculation formulas for the escape rate of trapped electrons into the loss cone in terms of time profiles of hard X-ray (HXR) and microwave (MW) emission have been obtained. It has been found that the evolution of the spectral indices of non-thermal emission depend on the regimes of the pitch angle diffusion of trapped particles into the loss cone. The properties of non-thermal electrons related to the HXR and MW emission of the solar flare on 2004 November 3 are studied with Nobeyama Radioheliograph, Nobeyama Radio Polarimeters, RHESSI, and Geostationary Operational Environmental Satellite observations. The spectral indices of non-thermal electrons related to MW and HXR emission remained constant or decreased, while the MW escape rate as distinguished from that of the HXRs increased. This may be associated with different diffusion regimes of trapped electrons into the loss cone. New arguments in favor of an important role of the superstrong diffusion for high-energy electrons in flare coronal loops have been obtained.

Authors: Jing Huang, Yihua Yan, and Yuri T. Tsap
Projects: Nobeyama Radioheliograph

Publication Status: ApJ, Volume 787, Page 123, 2014
Last Modified: 2014-06-12 14:54
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An analysis of solar radio burst events on December 1, 2004  

Jing Huang   Submitted: 2007-05-14 01:53

We present the analysis of the radio observations of December 1, 2004 from 07:00 UT-07:40 UT in the 1.100-1.340 GHz band by Solar Broadband Radio Dynamic Spectrometer(SBRS) in Huairou Station. There are three groups of radio fine structures during the impulsive phase of this flare denoted by N1, Z2, Z3. N1 has several emission lines with mixed fast and slow frequency drift rate which may reflect the conditions of flare loop and fast flows out from reconnection site; Z2 and Z3 are zebra patterns. The radio observations combined with hard X-ray and other observations show that the fine structures are connected with energetic particles. The information about magnetic field and energetic particle during the burst are also estimated based on our model.

Authors: Jing Huang, Yihua Yan, Yuying Liu
Projects: RHESSI,SoHO-EIT,SoHO-MDI

Publication Status: in press
Last Modified: 2007-05-14 10:20
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Quasi-periodic pulsations with varying period in multi-wavelength observations of an x-class flare
Energetic electron propagation in the decay phase of non-thermal flare emission
An analysis of solar radio burst events on December 1, 2004

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