### Trieste CALLISTO Station Setup and Observations of  Solar Radio Bursts by A. Marassi and C. Monstein

2022-06-21

A solar radio burst (SRB) is the intense solar radio emission often related to a solar flare and one of the possibly extreme space weather events which may affect Earth’s ionosphere and signal propagation, wireless communication, power grids and navigation systems. If an SRB occurs with the enhancement in L band radio flux, it could influence the Global Navigation Satellite Systems (GNSS) signals through direct radio wave interferences. The major […]

### Subarcsecond imaging of a solar active region filament with ALMA and IRIS by da Silva Santos et al.*

2022-06-07

Filaments (or prominences) are “clouds” of cool (<104 K) material suspended in the solar corona by up to tens of megameters above the photosphere, and they can be broadly divided into quiescent filaments and active region (AR) filaments. Although both of these structures have been observed for a long time, particularly in recent years by NASA’s IRIS telescope, there are open questions on the magnetic topology of filaments and the […]

### Density Turbulence and the Angular Broadening of Outer Heliospheric Radio Sources at High Latitudes and in the Ecliptic Plane by S. Tasnim et al.*

2022-05-24

We investigate angular broadening of radio wave scattering by density irregularities in the outer heliosphere and the very local interstellar medium (VLISM), incorporating an inner scale, latitudinal, and radial dependencies for the density fluctuation spectra and radiation propagation paths both near and out of the ecliptic plane. Outer Heliospheric Radio Emission Low-frequency radio wave emission was discovered in the distant heliosphere by the Voyager missions. A number of investigations [e.g., […]

### 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 […]

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