Solar Radio Science Highlights

Fundamental electromagnetic emissions by a weak electron beam in solar wind plasmas with density fluctuations
by C. Krafft and P. Savoini

2022-04-05

Solar radio bursts of Type III were currently observed since decades in the interplanetary space (Reid and Ratcliffe, 2014). They result from a series of successive processes arising in solar coronal and wind plasmas where Langmuir wave turbulence is radiated by electron beams generated during flares, leading ultimately to the emission of electromagnetic waves at the fundamental plasma frequency $\omega _{p}$ and its second harmonic. The Letter by Krafft and […]

New results from the spectral observations of solar coronal type II radio bursts
by R. Ramesh et al.*

2022-03-15

While it is widely accepted that the type II radio bursts observed in the interplanetary medium are due to the coronal mass ejections (CMEs), the energetic disturbance responsible for the shocks that generate the type II bursts observed in the near-Sun corona is still being debated.  Several studies indicate that CMEs are responsible for the coronal type II bursts too, but flares and various other eruptive activity have also been […]

Spectral Analysis of Solar Radio Type III Bursts from 20 kHz to 410 MHz
by K. Sasikumar Raja et al.*

2022-03-01

Solar type III radio bursts are produced by electron beams that are propagating along open magnetic field lines in the corona and interplanetary medium (IPM). Type III bursts drift from high frequency (~1 GHz) to 20 kHz at 1 AU and sometimes even beyond. It has been known for a long time that type IIIs are extremely variable, both in radio flux density and in observing frequency range. A statistical […]

Harvest of scientific results by Solar Orbiter Radio and Plasma Waves instrument
by Milan Maksimovic

2022-02-15

For a mission that has just entered its primary science phase, Solar Orbiter has already produced many remarkable results. Released on December 14, 2021, a special issue of Astronomy and Astrophysics brings together a wealth of studies and observations obtained during the mission’s cruise phase. Of the 56 articles published, 25 are based on data from the Radio & Plasma Waves (RPW) instrument (Maksimovic et al., A&A, 2020). The RPW […]

Signatures of Type III Solar Radio Bursts from Nanoflares: Modeling
by Sherry Chhabra et al.*

2022-02-01

Nanoflares are impulsive energy releases due to small breaks in coronal magnetic fields that have become stressed by photospheric convection. They are too small to be detected individually, but several lines of evidence suggest that they may be a primary candidate of coronal heating. But, whether nanoflares excite particles like full-sized flares is unknown (Vievering et al. 2021). A leading theory of particle acceleration predicts that the efficiency of acceleration […]

Radio Probing of Solar Wind Sources in Coronal Magnetic Fields
 by A. Koval et al.*

2022-01-18

The magnetic fields of the Sun govern the solar corona structure where the solar wind emanates and further accelerates supersonically. Therefore, the accurate observational data about the topology, and more significantly, quantities of the coronal magnetic field are pivotal for identifying the solar wind sources as well as for the Space Weather modeling where these data specify initial conditions. Magnetic-field strength values in the solar wind sources are derived from […]

Characterising coronal turbulence using snapshot imaging of radio bursts in 80 – 200 MHz
by Atul Mohan

2022-01-04

Metrewave solar type-III radio bursts offer a unique means to study the properties of turbulence across coronal heights. Theoretical models have shown that the apparent intensity and size of the burst sources evolve at sub-second scales due to turbulent scattering of radio waves close to their generation sites (Arzner & Magun, 1999; Kontar et al., 2019). The advent of high cadence snapshot spectroscopic imaging capabilities in meter wavebands have made […]

Particle-in-cell simulation of plasma emission in solar radio bursts
by T. M. Li et al.

2021-12-21

Solar radio radiation is one of the most sensitive emissions during solar eruptions, where type III radio bursts can provide clues for electron acceleration and propagation. Type III radio bursts are widely accepted to result from the plasma emission, which is observationally supported by the presence of Langmuir waves, and excited electromagnetic waves at fundamental and harmonic frequencies from the nonlinear wave coupling (Ginzburg & Zhelezniakov 1958). Such a mechanism […]

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