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.

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.

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 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.

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.

Type II Solar Radio Bursts over Solar Cycle 21

1994 ◽  
Vol 144 ◽  
pp. 283-284
Author(s):  
G. Maris ◽  
E. Tifrea
Keyword(s):  
Solar Radio ◽  
Interplanetary Space ◽  
Impulsive Phase ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Strong Energy ◽  
Mass Ejection ◽  
Geophysical Effect ◽  
Radio Event

The type II solar radio bursts produced by a shock wave passing through the solar corona are one of the most frequently studied solar activity phenomena. The scientific interest in this type of phenomenon is due to the fact that the presence of this radio event in a solar flare is an almost certain indicator of a future geophysical effect. The origin of the shock waves which produce these bursts is not at all simple; besides the shocks which are generated as a result of a strong energy release during the impulsive phase of a flare, there are also the shocks generated by a coronal mass ejection or the shocks which appear in the interplanetary space due to the supplementary acceleration of the solar particles.

Higher Harmonic Plasma Radiation in Type II Solar Radio Bursts

1990 ◽  
pp. 517-518
Author(s):  
V. V. Fomichev ◽  
I. M. Chertok ◽  
R. V. Gorgutsa ◽  
A. K. Markeev ◽  
B. Kliem ◽  
...  
Keyword(s):  
Solar Radio ◽  
Plasma Radiation ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Higher Harmonic

scholarly journals The correlation of solar radio bursts by magnetic activity and cosmic rays

1959 ◽  
Vol 9 ◽  
pp. 210-213
Author(s):  
A. R. Thompson
Keyword(s):  
Cosmic Rays ◽  
Radio Astronomy ◽  
Solar Radio ◽  
Magnetic Activity ◽  
Radio Bursts ◽  
Type Ii ◽  
Frequency Range ◽  
Sweep Frequency ◽  
Solar Radio Bursts ◽  
Auroral Particles

The sweep-frequency equipment at the Harvard Radio Astronomy Station, Fort Davis, Texas, has now been running continuously since 1956 September, recording solar radio activity in the frequency range from 100 to 580 Mc/s. The following contribution describes preliminary investigations of the correlation of the radio data with solar corpuscular emissions. This work was initiated to examine the well-known suggestions that the origins of the type II and type III radio bursts are associated with the ejection of auroral particles and cosmic rays respectively.

scholarly journals Recent Results of Meter-decameter Wave Observations of Solar Flares

1989 ◽  
Vol 104 (2) ◽  
pp. 185-189
Author(s):  
N. Copalswamy ◽  
M. R. Kundu
Keyword(s):  
Solar Flares ◽  
Solar Radio ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts ◽  
Type Iii ◽  
Type Iv

AbstractWe present recent results from meter-decameter imaging of several classes of solar radio bursts: Preflare activity in the form of type III bursts, correlated type IIIs from distant sources, and type II and moving type IV bursts associated with flares and CMEs.

scholarly journals Type II solar radio bursts: 2. Detailed comparison of theory with observations

2012 ◽  
Vol 117 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
D. S. Hillan ◽  
Iver H. Cairns ◽  
P. A. Robinson
Keyword(s):  
Solar Radio ◽  
Detailed Comparison ◽  
Radio Bursts ◽  
Type Ii ◽  
Solar Radio Bursts

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.

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