Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe
by V. Krupar et al.*

2020-03-31 275 views

Type III bursts belong among the strongest radio signals routinely observed by both space-borne and ground-based instrumentations. They are generated via the plasma emission mechanism, when beams of suprathermal electrons interact with the ambient plasma triggering radio emissions at the plasma frequency (the fundamental emission) or at its second harmonic (the harmonic emission). As the electron beams propagate outward from the Sun, radio emissions are generated at progressively lower frequencies […]

On the Source Position and Duration of a Solar Type III Radio Burst Observed by LOFAR
by P. Zhang et al.*

2020-01-21 515 views

Type III radio bursts are generated by non-thermal electron beams propagating through the solar corona and interplanetary space. In dynamic spectra, the flux of solar type III radio bursts have a time profile of rising and decay phases at a given frequency, which has been actively studied since the 1970s. There are several factors that may contribute to the observed duration of a type III radio burst: 1) The velocity […]

First observation of the solar Type III burst decay and its interpretation
by V. Melnik et al*

2020-01-07 259 views

Wild (1950) was the first to register and describe Type III bursts properties. These bursts are tracks of radio emission, which drift from high frequencies to low frequencies. Profiles of Type III bursts have a quick rise and slower fall. Wild supposed that electrons with high velocities, up to 0.3c (c is the speed of light), were responsible for Type III bursts based on their high frequency drift rates. Ginzburg […]

First imaging spectroscopy observations of puzzling solar drift pair bursts
by A. Kuznetsov and E. Kontar

2019-12-17 348 views

Drift pairs are a rare and puzzling type of solar radio emission, firstly identified by Roberts (1958). They occur at low frequencies (~10-100 MHz) and look like two parallel frequency-drifting narrow-band stripes separated in time. The drift rates (typically ~2-8 MHz/s) are intermediate between those of type II and type III bursts; both positive and negative frequency drifts are observed. The most enigmatic characteristic of drift pair bursts is that […]

Anisotropic radio-wave scattering in the solar corona
Nicolina Chrysaphi et al.*

2019-11-26 438 views

Solar radio emission is produced in the turbulent medium of the solar atmosphere, and its observed properties (source position, size, time profile, polarization, etc.) are significantly affected by the propagation of the radio waves from the emitter to the observer. Scattering of radio waves on random density irregularities has long been recognized as an important process for the interpretation of radio source sizes (e.g., Steinberg et al. 1971), positions (e.g., […]

Third harmonic electromagnetic radiation observed in Interplanetary Type III radio bursts by
M. Reiner et al.*

2019-09-17 582 views

Type III solar radio bursts, which appear as characteristic frequency-drifting features on radio dynamic spectra, are generated by energetic beams of electrons originating in solar active regions and propagating through the interplanetary medium. The remotely observed type III radiation consists of fundamental and harmonic components. Second harmonic electromagnetic radiation in type III solar radio bursts is well established at both high frequencies (metric and decametric wavelengths) and at low frequencies […]

Scaling-laws of Radio Spike Bursts and Their Constraints on New Solar Radio Telescopes
by Baolin Tan et al.

2019-06-18 381 views

Radio observation is one of the most important methods in solar physics and space science. Sometimes, it is almost the sole approach to observing physical processes such as the acceleration, emission, and propagation of non-thermal energetic particles, etc. Long-term observation and study have revealed that a strong solar radio burst is always composed of many small bursts with different time-scales. Among them, a radio spike burst is the smallest one, […]

The effect of scattering on the apparent positions of solar radio sources observed by LOFAR
by Mykola Gordovskyy

2019-05-21 448 views

Radio sources observed in the decametric range during type II and type III solar radio bursts are believed to be produced by coherent plasma emission due to electrostatic plasma oscillations induced by propagating suprathermal electrons (e.g. Ginzburg & Zhelezniakov 1958). This type of emission is a valuable tool for observational diagnostics of the upper corona. Produced at the local plasma frequency, $f_{pe}\rm{[kHz]}= 8.93 (n_e\rm{[cm}^{-3}\rm{]})^{-1/2}$ or its harmonic, plasma emission can reveal […]

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