Analysis of solar radio imaging-spectroscopic observations

2020 ◽  
Author(s):  
Yihua Yan ◽  
Minghui Zhang ◽  
Zhichao Zhou ◽  
Xingyao Chen ◽  
Chengming Tan ◽  
...  
Keyword(s):  
Solar Radio ◽  
Coronal Magnetic Field ◽  
Physical Processes ◽  
Plasma Parameters ◽  
Solar Radio Bursts ◽  
Spectroscopic Observations ◽  
Beam Velocity ◽  
Radio Imaging ◽  
Multiple Frequencies ◽  
Fine Structures

<p>Solar radio fine structures observed in wide frequency ranges are manifestations of the physical processes related to the energy release, particle accelerations and propagations, etc. The locations of these fine structures are mostly not clear so it is important to have imaging spectroscopic observations to address these problems.</p><p>Mingantu Spectral Radioheliograph (MUSER) is an aperture-synthesis imaging telescope, dedicated to observe the Sun, operating on multiple frequencies in dm to cm range. The ability of MUSER allows one to diagnose coronal magnetic field and the plasma parameters such as electron beam velocity, density, spectral index, etc.</p><p>During 2014 to 2019, MUSER has registered a number of solar radio bursts corresponding to 2 X-class, 15 M-class, 38 C-class, 19 B-class, 4 A-class and 5 below A-class flares as well as quiet Sun observations. Here we demonstrate some interesting events from MUSER imaging-spectroscopic observations.</p>

scholarly journals Separation of solar radio bursts in a complex spectrum

2010 ◽  
Vol 6 (S274) ◽  
pp. 150-152
Author(s):  
Hana Mészárosová ◽  
Ján Rybák ◽  
Marian Karlický ◽  
Karel Jiřička
Keyword(s):  
Radio Emission ◽  
Current Sheet ◽  
Solar Flares ◽  
Solar Radio ◽  
Radio Spectrum ◽  
New Method ◽  
Complex Spectrum ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Fine Structures

AbstractRadio spectra, observed during solar flares, are usually very complex (many bursts and fine structures). We have developed a new method to separate them into individual bursts and analyze them separately. The method is used in the analysis of the 0.8–2.0 GHz radio spectrum of the April 11, 2001 event, which was rich in drifting pulsating structures (DPSs). Using this method we showed that the complex radio spectrum consists of at least four DPSs separated with respect to their different frequency drifts (−115, −36, −23, and −11 MHz s−1). These DPSs indicate a presence of at least four plasmoids expected to be formed in a flaring current sheet. These plasmoids produce the radio emission on close frequencies giving thus a mixture of superimposed DPSs observed in the radio spectrum.

A Study of Solar Radio Bursts with Fine Structures during Flare/CME Events

Solar Physics ◽  
2008 ◽  
Vol 253 (1-2) ◽  
pp. 143-160 ◽  
Author(s):  
J. Huang ◽  
Y. H. Yan ◽  
Y. Y. Liu
Keyword(s):  
Solar Radio ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Fine Structures

scholarly journals Reflection of Magnetoionic Waves from a Steep Density Gradient. II. Incident Ordinary Mode

1985 ◽  
Vol 38 (5) ◽  
pp. 705 ◽  
Author(s):  
LM Hayes
Keyword(s):  
Density Gradient ◽  
Incident Wave ◽  
Solar Radio ◽  
Radio Bursts ◽  
Plasma Parameters ◽  
Solar Radio Bursts ◽  
Mode Wave ◽  
Ordinary Mode ◽  
Wave Parameters ◽  
Secondary Mode

We consider the case of an ordinary mode wave incident on a density discontinuity in an anisotropic plasma. The relative magnitudes of the two transmitted and two reflected modes produced by the incident 0 mode are calculated, and the dominant secondary mode is determined for different incident wave parameters and plasma parameters. An application of this work to the interpretation of the polarization of certain solar radio bursts is considered.

scholarly journals Interferometric imaging with LOFAR remote baselines of the fine structures of a solar type-IIIb radio burst

2020 ◽  
Vol 639 ◽  
pp. A115
Author(s):  
PeiJin Zhang ◽  
Pietro Zucca ◽  
Sarrvesh Seethapuram Sridhar ◽  
ChuanBing Wang ◽  
Mario M. Bisi ◽  
...  
Keyword(s):  
Radio Burst ◽  
Solar Radio ◽  
Source Size ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Harmonic Emission ◽  
Apparent Source ◽  
Solar Type ◽  
Fine Structures ◽  
Source Motion

Context. Solar radio bursts originate mainly from high energy electrons accelerated in solar eruptions like solar flares, jets, and coronal mass ejections. A sub-category of solar radio bursts with short time duration may be used as a proxy to understand wave generation and propagation within the corona. Aims. Complete case studies of the source size, position, and kinematics of short term bursts are very rare due to instrumental limitations. A comprehensive multi-frequency spectroscopic and imaging study was carried out of a clear example of a solar type IIIb-III pair. Methods. In this work, the source of the radio burst was imaged with the interferometric mode, using the remote baselines of the LOw Frequency ARray (LOFAR). A detailed analysis of the fine structures in the spectrum and of the radio source motion with imaging was conducted. Results. The study shows how the fundamental and harmonic components have a significantly different source motion. The apparent source of the fundamental emission at 26.56 MHz displaces away from the solar disk center at about four times the speed of light, while the apparent source of the harmonic emission at the same frequency shows a speed of < 0.02 c. The source size of the harmonic emission observed in this case is smaller than that in previous studies, indicating the importance of the use of remote baselines.

Characteristics of the fine structures in solar radio bursts at 3.2 cm

1997 ◽  
Vol 21 (3) ◽  
pp. 339-346
Author(s):  
Zhi-hai Qin ◽  
Guang-li Huang ◽  
Qi-jun Yao
Keyword(s):  
Solar Radio ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Fine Structures

scholarly journals SOLAR RADIO BURSTS WITH SPECTRAL FINE STRUCTURES IN PREFLARES

2015 ◽  
Vol 799 (1) ◽  
pp. 30 ◽  
Author(s):  
Yin Zhang ◽  
Baolin Tan ◽  
Marian Karlický ◽  
Hana Mészárosová ◽  
Jing Huang ◽  
...  
Keyword(s):  
Solar Radio ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Fine Structures

scholarly journals Decimetric Type-U Solar Radio Bursts and Associated EUV Phenomena on 2011 February 9

2021 ◽  
Vol 923 (2) ◽  
pp. 268
Author(s):  
Guannan Gao ◽  
Qiangwei Cai ◽  
Shaojie Guo ◽  
Min Wang
Keyword(s):  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Solar Radio ◽  
Impulsive Phase ◽  
Generation Rate ◽  
Reconnection Rate ◽  
Solar Radio Bursts ◽  
Flare Loop ◽  
Fluctuation Amplitude ◽  
Fine Structures

Abstract A GOES M1.9 flare took place in active region AR 11153 on 2011 February 9. With a resolution of 200 kHz and a time cadence of 80 ms, the reverse-drifting (RS) type-III bursts, intermittent sequence of type-U bursts, drifting pulsation structure (DPS), and fine structures were observed by the Yunnan Observatories Solar Radio Spectrometer (YNSRS). Combined information revealed by the multiwavelength data indicated that after the DPS was observed by YNSRS, the generation rate of type-U bursts suddenly increased to 5 times what it had been. In this event, the generation rate of type-U bursts may depend on the magnetic-reconnection rate. Our observations are consistent with previous numerical simulation results. After the first plasmoid produced (plasma instability occurred), the magnetic-reconnection rate suddenly increased by 5 to 8 times. Furthermore, after the DPS, the frequency range of the turnover frequency of type-U bursts was obviously broadened to thrice what it was before, which indicates a fluctuation amplitude of the density in the loop top. Our observations also support numerical simulations during the flare-impulsive phase. Turbulence occurs at the top of the flare loop and the plasmoids can trap nonthermal particles, causing density fluctuation at the loop top. The observations are generally consistent with the results of numerical simulations, helping us to better understand the characteristics of the whole physical process of eruption.

scholarly journals Detection of spike-like structures near the front of type-II bursts

2019 ◽  
Vol 624 ◽  
pp. A76 ◽  
Author(s):  
S. Armatas ◽  
C. Bouratzis ◽  
A. Hillaris ◽  
C. E. Alissandrakis ◽  
P. Preka-Papadema ◽  
...  
Keyword(s):  
Solar Radio ◽  
Average Duration ◽  
Total Duration ◽  
Small Scale ◽  
High Time Resolution ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Iv ◽  
Relative Bandwidth ◽  
Fine Structures

Aims. We examine high time resolution dynamic spectra for fine structures in type II solar radio bursts Methods. We used data obtained with the acousto-optic spectrograph receiver of the Artemis-JLS (ARTEMIS-IV) solar radio spectrograph in the 450–270 MHz range at 10 ms cadence and identified more than 600 short, narrowband features. Their characteristics, such as instantaneous relative bandwidth and total duration were measured and compared with those of spikes embedded in type IV emissions. Results. Type II associated spikes occur mostly in chains inside or close to the slowly drifting type II emission. These spikes coexist with herringbone and pulsating structures. Their average duration is 96 ms and their average relative bandwidth 1.7%. These properties are not different from those of type IV embedded spikes. It is therefore possible that they are signatures of small-scale reconnection along the type II shock front.

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