Community of European Solar Radio Astronomers – Page 8

Quasi-Periodic Particle Acceleration in a Solar Flare
by B. Clarke et al.*

2021-08-17

Quasi-periodic pulsations (QPPs) are defined as intensity modulations in the flare electromagnetic radiation as a function of time. These modulations have been found to have characteristic periodicities that range from < 1 s up to several minutes. QPPs were first associated with the impulsive phase of flares and observed in the hard X-ray (HXR) and radio wavebands (Parks & Winkler 1969). They have more recently been observed within the thermal […]

New results on the direct observations of thermal radio emission from a solar coronal mass ejection
by R. Ramesh et al.*

2021-08-03

Coronal mass ejections (CMEs) are large scale and energetic eruptions in the solar atmosphere during which $\approx$10$^{12}$-10$^{16}$g of magnetized coronal plasma are ejected into the heliosphere at speeds ranging from $\approx$100-3000km/s. They are mostly observed in whitelight using coronagraphs which use an occulter to block the bright light from the solar photosphere so that structures like CMEs can be observed with better contrast. But the size of the coronagraph occulters […]

New treatment of gyroresonance and free-free radio emissions from multi-thermal multi-component plasma
by A. Kuznetsov et al.*

2021-07-20

Thermal plasma in the solar corona is often characterized by a range of temperatures. This plasma can be described by the differential emission measure (DEM), which is a distribution of the thermal electron density square over temperature. The DEM-based treatment is widely used in application to the optically thin EUV and X-ray emissions. However, there has been no corresponding treatment in the radio domain, where optical depth of emission can […]

Energy budget of plasma motions, heating, and electron acceleration in a three-loop solar flare
by G. Motorina et al.*

2021-07-06

The solar flare phenomenon is a complex process in the solar atmosphere where non-potential magnetic energy is released and converted into other forms of energy, such as nonthermal energy of accelerated particles, thermal energy of heated flaring plasma, kinetic energy of eruptions, jets, up/down flows, and stochastic (turbulent) plasma motions. The processes lying behind initial division between energy components, distribution of these components among flaring loops and their evolution are […]

Narrowband Spikes Observed during the 2013 November 7 Flare
by M. Karlicky et al.

2021-06-22

Narrowband dm-spikes belong to the most interesting fine structures of solar radio bursts that are closely connected to primary flare energy-release processes (Krueger 1979) and observed in some cases near the Type III burst starting frequency. They occur in clouds of narrowband bursts with a typical duration less than 100 ms, frequency relative bandwidth 1-3 %, and brightness temperature up to $10^{15}$ K. For them several radio emission models were suggested. Earlier models suggested […]

Statistics of Low Frequency Cutoffs for Type III Radio Bursts Observed by Parker Solar Probe during Its Encounters 1–5 by Bing Ma et al

2021-06-08

Interplanetary (IP) type III radio bursts are deemed to generate in the interplanetary space because of their lower emission frequency ($0.01 – 10$ MHz) in terms of plasma emission. However, using the electron cyclotron maser emission (ECME), Wu et al. (2004) presented that IP type III radio bursts may generate in the low corona. The low frequency cutoffs is an important parameter to research the generation mechanism of type III […]

PIC Simulation of Double Plasma Resonance and Zebra Pattern of Solar Radio Bursts
by Li et al.*

2021-05-25

Zebra patterns (ZPs) represent a spectral fine structure with equidistant or almost-equidistant stripes of enhanced intensity against a broadband emission background, frequently observed in the dynamic spectra of solar radio bursts such as type IVs. There exist many scenarios for ZPs. The most-accepted one is the model of double plasma resonance (DPR) which, as its name indicates, means simultaneous actions of two kinds of resonance instabilities, i.e., the cyclotron resonance […]

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

2021-05-11

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 […]

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