scholarly journals On the Issue of the Origin of Type II Solar Radio Bursts

2021 ◽  
Vol 922 (1) ◽  
pp. 82
Author(s):  
Gennady Chernov ◽  
Valery Fomichev
Keyword(s):  
Shock Waves ◽  
Radio Emission ◽  
Solar Atmosphere ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Ii Radio Bursts ◽  
Type Ii Bursts ◽  
The Relationship

Abstract Type II solar radio bursts are among the most powerful events in the solar radio emission in the meter wavelength range. It is generally accepted that the agents generating type II radio bursts are magnetohydrodynamic shock waves. But the relationship between the shock waves and the other manifestations of the large-scale disturbances in the solar atmosphere (coronal mass ejections, Morton waves, EUW waves) remains unclear. To clarify a problem, it is important to determine the conditions of generation of type II radio bursts. Here, the model of the radio source is based on the generation of radio emission within the front of the collisionless shock wave where the Buneman instability of plasma waves is developed. In the frame of this model, the Alfvén magnetic Mach number must exceed the critical value, and there is a strict restriction on the perpendicularity of the front. The model allows us to obtain the information about the parameters of the shock waves and the parameters of the medium by the parameters of type II bursts. The estimates, obtained in this paper for several events with the band splitting of the fundamental and harmonic emission bands of the type II bursts, confirm the necessary conditions of the model. In this case the registration of type II radio bursts is an indication of the propagation of shock waves in the solar atmosphere, and the absence of type II radio bursts is not an indication of the absence of shock waves. Such a situation should be taken into account when investigating the relationship between type II radio bursts and other manifestations of solar activity.

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.

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.

scholarly journals Radio Data and Computer Simulations for Shock Waves Generated by Solar Flares

1980 ◽  
Vol 91 ◽  
pp. 251-255
Author(s):  
Alan Maxwell ◽  
Murray Dryer
Keyword(s):  
Shock Waves ◽  
Solar Corona ◽  
Computer Simulations ◽  
Solar Flares ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Fast Mode ◽  
Solar Radio Bursts ◽  
Radio Data

Solar radio bursts of spectral type II provide a prime diagnostic for the passage of shock waves, generated by solar flares, through the solar corona. In this investigation we have compared radio data on the shocks with computer simulations for the propagation of fast-mode MHD shocks through the solar corona. The radio data were recorded at the Harvard Radio Astronomy Station, Fort Davis, Texas. The computer simulations were carried out at NOAA, Boulder, Colorado.

scholarly journals On the Relative Position and Origin of Harmonics in the Spectra of Solar Radio Bursts of Spectral Types II And III

1962 ◽  
Vol 15 (2) ◽  
pp. 180 ◽  
Author(s):  
SF Smerd ◽  
JP Wild ◽  
KV Sheridan
Keyword(s):  
Solar Atmosphere ◽  
Relative Position ◽  
Solar Radio ◽  
Second Harmonic ◽  
Simple Theory ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Harmonic Emission ◽  
Type Iii

Observational results are given concerning the relative positions on the Sun's disk of the fundamental and second-harmonic emissions of solar radio bursts of spectral types II and III. Contrary to simple theory, the results indicate that it is common for the harmonic emission in type II bursts to arrive from directions corresponding to much lower heights in the solar atmosphere than the fundamental. The results for type III bursts are inconclusive but suggest the same trend.

Type II Solar Radio Bursts Observed with the Culgoora Radioheliograph during a Flare on 17 June 1968

1968 ◽  
Vol 1 (4) ◽  
pp. 141-142 ◽  
Author(s):  
K. Kai ◽  
D. J. McLean
Keyword(s):  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Flare Event ◽  
Type Iv ◽  
Type Ii Bursts

On 17 June 1968 we observed a flare event with the 80 MHz Culgoora radioheliograph consisting of a sequence of two type II bursts followed by enhanced emission possibly of type IV. In this paper we shall attempt to summarize some ofthe profuse data collected by the radioheliograph during this event and relate it to data from the radiospectrograph and Hα films of the associated flare (the Hα films were kindly made available by the Division of Physics, CSIRO).

scholarly journals CONNECTION OF THE INTENSITY OF THE FLUX OF SCR PROTONS WITH THE VELOCITY OF THE CME AND WITH THE FADING OF THE RADIO EMISSION OF THE SUN IN THE DECAMETER RANGE

2021 ◽  
Vol 34 ◽  
pp. 76-80
Author(s):  
E. A. Isaeva
Keyword(s):  
Shock Waves ◽  
Radio Emission ◽  
Solar Radio ◽  
Proton Flux ◽  
Solar Radio Emission ◽  
Radio Bursts ◽  
Decameter Range ◽  
Coronal Shock ◽  
The Relationship ◽  
The Continuum

The relationship between SCR and CME and with fading of the continuum of noise storms and typeIV radio bursts in the decameter range is investigated. It was shown earlier that about 60% of CMEs associated with solar proton events are accompanied by deep fading of the solar radio emission in the decameter range, which coin-cides in time with CME registration. It has also been shown that fading is characterized by fading depth, the frequency bandwidth in which the fading occurs, as well as the duration of the fading and the frequency at which the maximum fading depth is observed. Further detailed studies have shown that for proton events accompanied by fading of the solar radio emission in the decameter range, the relationship between the intensity of the SCR proton flux and the CME velocity is much worse than for events without fading of the solar radio emission in the decameter range. However, it was foundthat for such events, the relationship between the flux of SCR protons and the CME velocity significantly increases if we take into account the fading depth of the solar radio emission in the decameter range.Earlier in (Isaeva, 2019), the results of a study of the relationship between the intensity of fading of the continuum of noise storms with the parameters of X-ray bursts, with the CME velocity and the velocity of coronal shock waves, as well as with the intensity of the SCR proton flux were presented. This paper presents the results of studying the relationship between the intensity of the SCR proton flux withthe parameters of type II and IV radio bursts, as well as with the CME velocity and with the velocity of coronal shock waves, depending on the intensity of fading of the solar radio emission in the decameter range at a frequency of 27 MHz. The frequency of 27 MHz was chosen because in the region of this frequency the maximum fading depth of the solar radio emission in the decameter range is observed.  

scholarly journals The Positions and Movements of the Sources of Solar Radio Bursts of Spectral Type II

1963 ◽  
Vol 16 (2) ◽  
pp. 240 ◽  
Author(s):  
AA Weiss
Keyword(s):  
Spectral Type ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Frequency Range ◽  
Solar Radio Bursts ◽  
Dynamic Spectra ◽  
Type Ii Radio Bursts ◽  
Optical Flare ◽  
East West

The east-west position coordinates of the sources of 22 type II radio bursts, measured in the range 40-70 Mc/s using a swept-frequency interferometer, are analysed and discussed, in conjunction with dynamic spectra obtained in the frequency range 15-210 Mc/s. Many bursts are multiple and consist of a number of separate bursts excited by disturbances ejected in different directions from the vicinity of an optical flare, which may be equally complex.

scholarly journals Estimation of Shock Thickness from Dynamic Spectra of Type II Bursts

1980 ◽  
Vol 91 ◽  
pp. 257-259
Author(s):  
H. S. Sawant ◽  
S. S. Degaonkar ◽  
S. K. Alurkar ◽  
R. V. Bhonsle
Keyword(s):  
Solar Radio ◽  
Narrow Band ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Fast Electrons ◽  
Dynamic Spectra ◽  
Type Ii Bursts ◽  
Shock Thickness

Twenty type II solar radio bursts were observed during the period 1968 to 1972 by a solar radio spectroscope (240-40 MHz) at Ahmadebad. Intensity variations in type II bursts as a function of frequency and time are sometimes observed in their dynamic spectra. This fine structure enables determination of the shock thickness of the order of a few hundred to a few thousand kilometers. In a few cases, an interaction between streams of fast electrons and propagating shocks is clearly evidenced by simultaneous observations of short duration narrow band structures in type III bursts and type II bursts.

On the Longitudinal Distribution of Solar Type II Bursts

1980 ◽  
Vol 4 (1) ◽  
pp. 59-61 ◽  
Author(s):  
C. S. Wright
Keyword(s):  
Uniform Distribution ◽  
Solar Radio ◽  
Source Mechanism ◽  
Longitudinal Distribution ◽  
Central Meridian ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Solar Type ◽  
Type Ii Bursts

Distributions in longitude of solar radio bursts often are compiled by identifiying the position of the burst with the position of the associated H-Alpha flare. Early work on the longitudinal distribution of type II bursts compiled in this way (eg. Maxwell and Thompson 1962) indicated an approximately uniform distribution. Subsequently Svestka and Fritzova — Svestkova (1974) and Svestka (1976) published a distribution of 244 H-Alpha flares with which type II bursts were associated (hereafter called type II flares) that showed marked deficits near central meridian and the limb (Fig. 1). They suggested that the distribution was a product of propagational selection, being in some way dependant on the nature of the type II source mechanism as well as the manner by which the radiation reached the observer. On this basis they argued that the number of type II bursts that occurred near central meridian and near the limb was underestimated.

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