Community of European Solar Radio Astronomers – Page 15

Microwave Spectral Imaging of an Erupting Magnetic Flux Rope During a Large Solar Flare
by B. Chen et al.*

2020-09-22

Magnetic flux ropes are believed to be the centerpiece of the three-part structure of coronal mass ejections. In the standard model of eruptive solar flares, flux rope eruption also induces the impulsive flare energy release through magnetic reconnection. Signatures of flare-associated flux ropes in the low solar corona have been frequently reported in extreme ultraviolet (EUV) wavelengths, particularly the so-called EUV “hot channel” structures (see, e.g., Cheng et al. 2017 […]

Polarisation and source structure of solar stationary type IV radio bursts
by C. Salas-Matamoros and L. Klein

2020-09-08

A coronal mass ejection (CME) is a phenomenon which produces large-scale ejections of mass and magnetic field from the lower corona into the interplanetary space (e.g. Forbes, 2000). The ejection of CMEs is often accompanied by the radio emission from non-thermal electrons. Particularly, stationary type IV continua are thought to be emitted by electrons in closed magnetic structures in the wake of the rising CME. Although basic properties, such as […]

Radio echo in the turbulent corona and simulations of solar drift-pair radio bursts observed with LOFAR
by Kuznetsov et al

2020-08-18

Drift-pair bursts are a rare and mysterious type of fine spectral structures in the low-frequency domain of solar radio emission. First identified by Roberts (1958), they appear in the dynamic spectrum as two parallel frequency-drifting bright stripes separated in time; the trailing stripe seems to repeat the morphology of the leading one with a typical delay of ~1–2 s (see, e.g., Figure 1). Recent imaging spectroscopy observations with the LOw-Frequency […]

Observations of fragmented energy release during solar flare emission
by R. Ramesh et al.*

2020-07-28

Type III radio bursts from the Sun are signatures of energetic (∼1–100 keV) electrons, accelerated at the reconnection sites, propagating upward through the corona into the interplanetary medium along open magnetic field lines. The emission mechanism of the bursts is widely believed to be due to coherent plasma processes. The bursts are observed typically in the frequency range $\approx 1\,$GHz$ – 10\,$kHz, which corresponds to radial distance range between the […]

Density and magnetic field turbulence in solar flares estimated from radio zebra observations
by M. Karlicky and L. Yasnov

2020-07-14

Solar flares are characterized by fast plasma flows. In such plasma flows owing to the Kelvin-Helmholtz instability the maqnetohydrodynamic turbulence can be generated. Although, the turbulence plays an important role in solar flares, e.g., in acceleration of particles, a knowledge about the level of this turbulence is still very limited. In the present study we estimate the levels of this turbulence. For this purpose we use observations of the so called zebra […]

First radio evidence of impulsive heating contribution to the quiet solar corona
by Surajit Mondal et al

2020-06-30

The solar community has been trying to understand the mechanism responsible for coronal heating for several decades now. In the past decade, a number of studies have shown that the active regions and the coronal loops are heated impulsively. However, such a consensus is yet to be reached for the quiet sun. Past searches for impulsive events in the EUV and X-ray are yet to provide conclusive evidence in favour […]

Fast CME caused by the eruption of a quiescent prominence
by V. Grechnev and I. Kuzmenko

2020-06-09

CMEs can be the sources of space-weather disturbances. Shock waves expanding ahead of fast CMEs and associated flares are the probable sources of energetic protons. Two categories of CMEs have traditionally been identified depending on the presence of conspicuous chromospheric emissions during their development. Flare-associated CMEs erupt from active regions, carry stronger magnetic fields, can reach higher speeds and cause stronger space-weather disturbances. Non-flare-associated CMEs develop in eruptions of large […]

First observation of a transitioning Type II solar radio burst using the Low-Frequency Array (LOFAR)
by Nicolina Chrysaphi et al

2020-05-26

Type II solar radio bursts are believed to be excited by shock waves. They are often linked to shocks driven by solar eruptive events like Coronal Mass Ejections (CMEs) and solar flares, and are characterised by a slow drift from high to low frequencies thought to reflect the speed with which the shock propagates away from the Sun. Shock-excited emissions that show very little or no frequency drift are known […]

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