scholarly journals Electron Acceleration at Quasi-Parallel Shocks in The Solar Corona and Its Signature in Solar Type II Radio Bursts

1994 ◽  
Vol 142 ◽  
pp. 577-581
Author(s):  
G. Mann ◽  
H. Lühr
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Radio Bursts ◽  
Type Ii ◽  
Radio Radiation ◽  
Earth’S Bow Shock ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Field Geometry ◽  
The Magnetic Field

AbstractRecently, strong large amplitude magnetic field structures (SLAMS) have been observed as a common phenomenon in the vicinity of the quasi-parallel region of Earth’s bow shock. A quasi-parallel shock transition can be considered as a patchwork of SLAMS. Using the data of the AMPTE/IRM magnetometer the properties of SLAMS are studied. Within SLAMS the magnetic field is strongly deformed and, thus, the magnetic field geometry is locally swung into a quasi-perpendicular regime. Therefore, electrons can locally be accelerated to high energies within SLAMS. Assuming that SLAMS also exist in the vicinity of supercritical, quasi-parallel shocks in the solar corona, they are able to generate radio radiation via the enhanced Langmuir turbulence excited by the accelerated electrons. Since SLAMS are connected with strong density enhancements, the aforementioned mechanism can explain the multiple-lane structure often occurred in solar Type II radio bursts.Subject headings: acceleration of particles — Earth — shock waves — Sun: corona — Sun: radio radiation

scholarly journals Analyzing the propagation of EUV waves and their connection with type II radio bursts by combining numerical simulations and multi-instrument observations

2020 ◽  
Vol 644 ◽  
pp. A90
Author(s):  
A. Koukras ◽  
C. Marqué ◽  
C. Downs ◽  
L. Dolla
Keyword(s):  
Magnetic Field ◽  
Wave Front ◽  
Ray Tracing ◽  
Radio Burst ◽  
Radio Bursts ◽  
Type Ii ◽  
Fast Mode ◽  
Type Ii Radio Bursts ◽  
The Magnetic Field ◽  
Burst Emission

Context. EUV (EIT) waves are wavelike disturbances of enhanced extreme ultraviolet (EUV) emission that propagate away from an eruptive active region across the solar disk. Recent years have seen much debate over their nature, with three main interpretations: the fast-mode magneto-hydrodynamic (MHD) wave, the apparent wave (reconfiguration of the magnetic field), and the hybrid wave (combination of the previous two). Aims. By studying the kinematics of EUV waves and their connection with type II radio bursts, we aim to examine the capability of the fast-mode interpretation to explain the observations, and to constrain the source locations of the type II radio burst emission. Methods. We propagate a fast-mode MHD wave numerically using a ray-tracing method and the WKB (Wentzel-Kramers-Brillouin) approximation. The wave is propagated in a static corona output by a global 3D MHD Coronal Model, which provides density, temperature, and Alfvén speed in the undisturbed coronal medium (before the eruption). We then compare the propagation of the computed wave front with the observed wave in EUV images (PROBA2/SWAP, SDO/AIA). Lastly, we use the frequency drift of the type II radio bursts to track the propagating shock wave, compare it with the simulated wave front at the same instant, and identify the wave vectors that best match the plasma density deduced from the radio emission. We apply this methodology for two EUV waves observed during SOL2017-04-03T14:20:00 and SOL2017-09-12T07:25:00. Results. The simulated wave front displays a good qualitative match with the observations for both events. Type II radio burst emission sources are tracked on the wave front all along its propagation. The wave vectors at the ray-path points that are characterized as sources of the type II radio burst emission are quasi-perpendicular to the magnetic field. Conclusions. We show that a simple ray-tracing model of the EUV wave is able to reproduce the observations and to provide insight into the physics of such waves. We provide supporting evidence that they are likely fast-mode MHD waves. We also narrow down the source region of the radio burst emission and show that different parts of the wave front are responsible for the type II radio burst emission at different times of the eruptive event.

On the Possibility of Radio Emission from Quasi-parallel and Quasi-perpendicular Propagation of Shocks

2000 ◽  
Vol 179 ◽  
pp. 259-262
Author(s):  
A. Shanmugaraju ◽  
S. Umapathy
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Radio Bursts ◽  
Type Ii ◽  
Simple Analysis ◽  
Type Ii Radio Bursts ◽  
Solar Type ◽  
Type Ii Bursts

AbstractA set of 21 solar type II radio bursts observed using Hiraiso radio spectrograph have been analysed to study the direction of propagation of coronal shocks. A simple analysis is carried out to find the approximate angle between the shock normal and magnetic field by solving the Rankine-Hugoniot MHD relation with assumption of Alfven speed and plasma beta. From this analysis, it is suggested that both quasi-parallel shocks (favourable) and quasi-perpendicular shocks can generate type II bursts depending upon the circumstances of the corona.

scholarly journals AN OBSERVATIONAL REVISIT OF BAND-SPLIT SOLAR TYPE-II RADIO BURSTS

2015 ◽  
Vol 812 (1) ◽  
pp. 52 ◽  
Author(s):  
Guohui Du ◽  
Xiangliang Kong ◽  
Yao Chen ◽  
Shiwei Feng ◽  
Bing Wang ◽  
...  
Keyword(s):  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Solar Type

Polarization and Fragmentation of Solar Type II Radio Bursts

2003 ◽  
Vol 592 (2) ◽  
pp. 1234-1240 ◽  
Author(s):  
G. Thejappa ◽  
P. Zlobec ◽  
R. J. MacDowall
Keyword(s):  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Solar Type

The solar type II radio bursts of 7 March 2012: Detailed simulation analyses

2014 ◽  
Vol 119 (8) ◽  
pp. 6042-6061 ◽  
Author(s):  
J. M. Schmidt ◽  
Iver H. Cairns ◽  
V. V. Lobzin
Keyword(s):  
Radio Bursts ◽  
Type Ii ◽  
Detailed Simulation ◽  
Type Ii Radio Bursts ◽  
Solar Type

scholarly journals Height of shock formation in the solar corona inferred from observations of type II radio bursts and coronal mass ejections

2013 ◽  
Vol 51 (11) ◽  
pp. 1981-1989 ◽  
Author(s):  
N. Gopalswamy ◽  
H. Xie ◽  
P. Mäkelä ◽  
S. Yashiro ◽  
S. Akiyama ◽  
...  
Keyword(s):  
Solar Corona ◽  
Coronal Mass Ejections ◽  
Shock Formation ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts

Statistical Characteristics of CMEs and Flares Associated with Solar Type II Radio Bursts

Solar Physics ◽  
2003 ◽  
Vol 217 (2) ◽  
pp. 301-317 ◽  
Author(s):  
A. Shanmugaraju ◽  
Y.-J. Moon ◽  
M. Dryer ◽  
S. Umapathy
Keyword(s):  
Statistical Characteristics ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Solar Type

scholarly journals Catalogue of solar type II radio bursts observed from September 1990 to December 1993 and their statistical analysis

1996 ◽  
Vol 119 (3) ◽  
pp. 489-498 ◽  
Author(s):  
G. Mann ◽  
A. Klassen ◽  
H.-T. Classen ◽  
H. Aurass ◽  
D. Scholz ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Ii Radio Bursts ◽  
Solar Type

Shock Drift Acceleration and Type II Solar Radio Bursts

1994 ◽  
Vol 11 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Arthur G. Street ◽  
Lewis Ball ◽  
D. B. Melrose
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Shock Front ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Ii Bursts ◽  
Herringbone Structure ◽  
The Magnetic Field

AbstractShock drift acceleration of the electrons which produce herringbone structure in type II bursts is considered. A non-coplanar component of the magnetic field within the shock front and an electric field across the shock are taken into account. A quantitative difficulty with shock drift acceleration is identified, and possible ways of overcoming the difficulty are outlined.

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