Conditions needed for generation of type II radio emission in the interplanetary space

2021 ◽  
Author(s):  
Immanuel Christopher Jebaraj ◽  
Athanasios Kouloumvakos ◽  
Jasmina Magdalenic ◽  
Alexis Rouillard ◽  
Vratislav Krupar ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Radio Emission ◽  
Interplanetary Space ◽  
Region Of Interest ◽  
Type Ii ◽  
Radio Observations ◽  
Wave Parameters ◽  
First Results ◽  
Radio Signature

<p>Eruptive events such as Coronal mass ejections (CMEs) and flares cangenerate shock waves. Tracking shock waves and predicting their arrival at Earth is a subject of numerous space weather studies. Ground-based radio observations allow us to locate shock waves in the low corona while space-based radio observations provide us opportunity to track shock waves in the inner heliosphere. We present a case study of CME/flare event, associated shock wave and its radio signature, i.e. type II radio burst.</p><p>In order to analyze the shock wave parameters, we employed a robust paradigm. We reconstructed the shock wave in 3D using multi-viewpoint observations and modelled the evolution of its parameters using a 3D MHD background coronal model produced by the MAS (Magnetohydrodynamics Around a Sphere).</p><p>To map regions on the shock wave surface, possibly associated with the electron acceleration, we combined 3D shock modelling results with the 3D source positions of the type II burst obtained using the radio triangulation technique. We localize the region of interest on the shock surface and examine the shock wave parameters to understand the relationship between the shock wave and the radio event. We analyzed the evolution of the upstream plasma characteristics and shock wave parameters during the full duration of the type II radio emission. First results indicate that shock wave geometry and its relationship with shock strength play an important role in the acceleration of electrons responsible for the generation of type II radio bursts.</p>

Radio Evidence for Electron Acceleration by Transverse Shock Waves in Herringbone Type II Solar Bursts

1980 ◽  
Vol 4 (1) ◽  
pp. 53-55 ◽  
Author(s):  
R. T. Stewart ◽  
A. Magun
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Solar Corona ◽  
Direct Evidence ◽  
Electron Acceleration ◽  
Type Ii ◽  
Radio Observations ◽  
Type Iii ◽  
Solar Bursts ◽  
Herringbone Structure

Perhaps the most direct evidence to date for shock wave acceleration of electrons in the solar corona is provided by radio observations of Type II bursts containing herringbone structure (Roberts 1959). On spectral records the herringbones appear to resemble miniature forward and reverse drift Type III bursts extending above and below the Type II backbone.

scholarly journals Acceleration, Containment and Emission of High Energy Flare Particles: Radio Evidence

1974 ◽  
Vol 57 ◽  
pp. 423-435 ◽  
Author(s):  
A. Boischot
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Solar Atmosphere ◽  
Impulsive Phase ◽  
High Energy ◽  
Continuous Phase ◽  
List Type ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Number

The existence of non thermal radio bursts provide evidences for the acceleration of electrons in the solar atmosphere.It is shown, from the characteristics of the bursts, that the electrons are accelerated in at least four different phases: (1)An impulsive phase which gives μib and III bursts.(2)A gradual phase which gives μIV and S1IV bursts.(3)A quasi-continuous phase which gives S2IV bursts and noise storms.(4)An acceleration by shock waves gives type II bursts.(5)Eventually, another shock-wave acceleration giving the moIV burst.

Rankine–Hugoniot-Berechnungen für Nichtgleichgewichts-Plasmen

1966 ◽  
Vol 21 (11) ◽  
pp. 1960-1963
Author(s):  
J. Artmann
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Pressure Ratio ◽  
Density Ratio ◽  
Charged Particles ◽  
Strong Shock ◽  
Ion Temperature ◽  
Saha Equation ◽  
Wave Parameters ◽  
Strong Shock Waves

In optically thin plasmas produced by strong shock waves the SAHA equation is no longer valid to describe the conditions directly behind the shock wave. Photoionisation may be neglected in the balance of production and recombination of charged particles. For the case of nonequilibrium a calculation assuming various ratios of electron to ion temperature (ϑ= TeT) shows that the shock wave parameters are described sufficiently well by the Korona-equation. Temperature, density ratio and electron density are increased with increasing ϑ whereas the pressure ratio is independent of the kind of equilibrium and ϑ.

scholarly journals Interplanetary spread of solar energetic protons near a high-speed solar wind stream

2019 ◽  
Vol 624 ◽  
pp. A47 ◽  
Author(s):  
N. Wijsen ◽  
A. Aran ◽  
J. Pomoell ◽  
S. Poedts
Keyword(s):  
Shock Wave ◽  
Solar Wind ◽  
Shock Waves ◽  
Interplanetary Space ◽  
Radial Distance ◽  
Slow Solar Wind ◽  
Solar Wind Stream ◽  
Particle Intensity ◽  
Solar Energetic Protons ◽  
The Imf

Aims. We study how a fast solar wind stream embedded in a slow solar wind influences the spread of solar energetic protons in interplanetary space. In particular, we aim at understanding how the particle intensity and anisotropy vary along interplanetary magnetic field (IMF) lines that encounter changing solar wind conditions such as the shock waves bounding a corotating interaction region (CIR). Moreover, we study how the intensities and anisotropies vary as a function of the longitudinal and latitudinal coordinate, and how the width of the particle intensities evolves with the heliographic radial distance. Furthermore, we study how cross-field diffusion may alter these spatial profiles. Methods. To model the energetic protons, we used a recently developed particle transport code that computes particle distributions in the heliosphere by solving the focused transport equation (FTE) in a stochastic manner. The particles are propagated in a solar wind containing a CIR, which was generated by the heliospheric model, EUHFORIA. We study four cases in which we assume a delta injection of 4 MeV protons spread uniformly over different regions at the inner boundary of the model. These source regions have the same size and shape, yet are shifted in longitude from each other, and are therefore magnetically connected to different solar wind conditions. Results. The intensity and anisotropy profiles along selected IMF lines vary strongly according to the different solar wind conditions encountered along the field line. The IMF lines crossing the shocks bounding the CIR show the formation of accelerated particle populations, with the reverse shock wave being a more efficient accelerator than the forward shock wave. The longitudinal intensity profiles near the CIR are highly asymmetric in contrast to the profiles obtained in a nominal solar wind. For the injection regions that do not cross the transition zone between the fast and slow solar wind, we observe a steep intensity drop of several orders of magnitude near the stream interface (SI) inside the CIR. Moreover, we demonstrate that the longitudinal width of the particle intensity distribution can increase, decrease, or remain constant with heliographic radial distance, reflecting the underlying IMF structure. Finally, we show how the deflection of the IMF at the shock waves and the compression of the IMF in the CIR deforms the three-dimensional shape of the particle distribution in such a way that the original shape of the injection profile is lost.

A Simplified Presentation of Shock Wave Parameters in Dissociating Air Flow

1960 ◽  
Vol 64 (595) ◽  
pp. 438-439
Author(s):  
T. R. F. Nonweiler
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Shock Waves ◽  
Chemical Equilibrium ◽  
Incident Flow ◽  
Perfect Gas ◽  
Thermodynamic State ◽  
Independent Variables ◽  
Wave Parameters ◽  
Temperature And Pressure

As is well known, the analysis of shock waves is complicated when the gas becomes dissociated on passage through the wave. As well as showing a dependence on the Mach number of the incident flow and non-dimensional quantities characteristic of the nature of the gas, as does the analysis when applied to a perfect gas, it then also shows a dependence on the thermodynamic state of the upstream air, as described for instance by its temperature and pressure. A growing number of calculations is becoming available, especially for air in complete thermal and chemical equilibrium, but the interpolation to give results appropriate to the three independent variables (of upstream state and incident velocity) needed in any particular application can often be rather troublesome, and one has still less faith in extrapolation.

Tracing shock waves from the corona to 1 AU: Type II radio emission and relationship with CMEs

2001 ◽  
Vol 106 (A11) ◽  
pp. 25301-25312 ◽  
Author(s):  
Yolande Leblanc ◽  
George A. Dulk ◽  
Angelos Vourlidas ◽  
Jean-Louis Bougeret
Keyword(s):  
Shock Waves ◽  
Radio Emission ◽  
Type Ii

scholarly journals Using radio triangulation to understand the origin of two subsequent type II radio bursts

2020 ◽  
Vol 639 ◽  
pp. A56
Author(s):  
I. C. Jebaraj ◽  
J. Magdalenić ◽  
T. Podladchikova ◽  
C. Scolini ◽  
J. Pomoell ◽  
...  
Keyword(s):  
Shock Wave ◽  
Radio Emission ◽  
Spatial Information ◽  
Low Frequency ◽  
Temporal Association ◽  
Type Ii ◽  
Flare Event ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
The Relationship

Context. Eruptive events such as coronal mass ejections (CMEs) and flares accelerate particles and generate shock waves which can arrive at Earth and can disturb the magnetosphere. Understanding the association between CMEs and CME-driven shocks is therefore highly important for space weather studies. Aims. We present a study of the CME/flare event associated with two type II bursts observed on September 27, 2012. The aim of the study is to understand the relationship between the observed CME and the two distinct shock wave signatures. Methods. The multiwavelength study of the eruptive event (CME/flare) was complemented with radio triangulation of the associated radio emission and modelling of the CME and the shock wave employing MHD simulations. Results. We found that, although temporal association between the type II bursts and the CME is good, the low-frequency type II (LF-type II) burst occurs significantly higher in the corona than the CME and its relationship to the CME is not straightforward. The analysis of the EIT wave (coronal bright front) shows the fastest wave component to be in the southeast quadrant of the Sun. This is also the quadrant in which the source positions of the LF-type II were found to be located, probably resulting from the interaction between the shock wave and a streamer. Conclusions. The relationship between the CME/flare event and the shock wave signatures is discussed using the temporal association, as well as the spatial information of the radio emission. Further, we discuss the importance and possible effects of the frequently non-radial propagation of the shock wave.

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