Langmuir wave motion observed in the most intense radio sources in the sky
by H. Reid and E. Kontar

2021-08-31 290 views

The Sun routinely produces energetic electrons in its outer atmosphere that subsequently travel through interplanetary space. These electron beams generate Langmuir waves in the background plasma, producing type III radio bursts that are the brightest radio sources in the sky (Suzuki & Dulk, 1985). These solar radio bursts also provide a unique opportunity to understand particle acceleration and transport which is important for our prediction of extreme space weather events […]

Parametric simulation studies on the wave propagation of solar radio emission: the source size, duration, and position by Zhang et al.*

2021-05-11 219 views

The imaging and spectroscopy observations of solar radio bursts can provide information on the non-thermal electrons associated with the transient energy release in the solar active region and the parameters of the background plasma. However,  the corona plasma is an inhomogeneous refractive media for solar radio waves. Propagation effects, namely the refraction and scattering of waves, can cause the deformation of the observed radio source, including the expansion of the […]

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

2020-03-31 270 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 […]

Short-period Waves in Flare Loops: Possible Vehicle for Flare Energy Transport
by Sijie Yu et al

2019-03-26 382 views

Solar flares involve the sudden release of magnetic energy in the solar corona. Accelerated nonthermal electrons have been often invoked as the primary means for transporting the bulk of the released energy to the lower solar atmosphere. However, significant challenges remain for this scenario, especially in accounting for the large number of accelerated electrons inferred from observations. Propagating magnetohydrodynamics (MHD) waves, particularly those with subsecond/second-scale periods, have been proposed as […]

LOFAR observations of Fine Fundamental and Harmonic Structures in Solar Radio Bursts
by Xingyao Chen et al*

2018-05-01 632 views

Type III solar radio bursts are believed to be the most sensitive signatures of near-relativistic electron beam propagation in the corona. These intense bursts of solar radio emissions sometimes appear in the dynamic spectrum as a chain of several elementary bursts, which are known as striae, so an individual burst is composed of myriad of such stria (de La Noe & Boischot, 1972). Although there are several generation mechanisms of […]

Solar Type-IIIb Radio Bursts as Tracers for Electron Density Fluctuations in the Corona
by V. Mugundhan et al.*

2018-04-17 281 views

Type III bursts are generated when an electron accelerated close to speed of light excite the layers of coronal plasma they encounter when travelling away from the sun. These bursts are seen in a time-frequency-intensity image (called dynamic spectrum, as the time variation of the spectrum is visualized by it) as a bright patch, drifting from high to low frequencies on short time-scales ($\approx$ few-seconds). At times, along the path […]

Observations of solar radio burst fine structures with LOFAR
by E. Kontar et al.*

2017-11-28 1,360 views

During solar flares, electrons are accelerated up to relativistic speeds. As they propagate upwards through the solar corona, they produce so-called type III radio bursts. These type III bursts often demonstrate fine structure, with their spectra consisting of multiple narrowband “striae”; most likely, these structures are caused by small-scale density inhomogeneities of the coronal plasma so that the subsequent fundamental plasma processes that produce the radio bursts is produced in […]

Solar wind density turbulence from 10 to 45 solar radii
by K. Sasikumar Raja et al.*

2017-06-06 615 views

The extended solar corona and the solar wind is a rich testbed for studying the properties of magnetohydrodynamic (MHD) turbulence. While most solar wind turbulence theories only treat incompressible turbulence, density irregularities are present in the solar wind, and are manifested through fluctuations in the refractive index. Knowledge of density turbulence impacts our understanding of the solar wind significantly, and is important for interpreting a variety of observations. It is […]