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

2020-05-26 376 views

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 […]

Spectral Structures of Type II Solar Radio Bursts and Solar Energetic Particles
by K. Iwai

2020-03-03 312 views

Solar eruptive phenomena, such as flares and coronal mass ejections (CMEs), generate high-energy particles called solar energetic particles (SEPs). Severe SEP events sometimes cause satellite anomalies and radiation exposure to humans in space. Hence, understanding and forecasting SEPs is an important issue in space weather. Type II solar radio bursts are nonthermal radio emissions with negative frequency drift observed between the metric and kilometric frequency range. They are thought to […]

Evolution of Coronal and Interplanetary Shock Waves Inferred from a Radio Burst
by Khaled Alielden

2020-02-04 209 views

Estimating the kinematics of Type II radio-burst sources, which are recognized as a shock waves, using electron-density models is inaccurate and restricted. In this article, a blast-expansion technique is used for the first time for estimating the kinematics of a Type II radio-burst source without using electron-density models by studying the density variation along the leading surface of the coronal mass ejections (CMEs) (herein: ejecta) during Type-II radio-burst emission. This […]

Are Solar Energetic Particle Events and Type II Bursts Associated with Fast and Narrow Coronal Mass Ejections?
by S. W. Kahler et al.*

2019-12-10 197 views

Gradual solar energetic (E > 10 MeV) particle (SEP) events, lasting several days, are produced in coronal/interplanetary shocks driven by fast (VCME ≥ 900 kms−1) coronal mass ejections (CMEs) associated with type II radio bursts.  The basic paradigm is that CMEs with VCME > Vf, the plasma fast-mode speed, drive shocks that can accelerate seed particles to the high energies observed as SEP events in space as well as electrons […]

Imaging spectroscopy of fiber bursts
by C. Alissandrakis*

2019-10-15 344 views

Fibers are short metric/decimetric bursts with a drift rate between type II and type III bursts, usually appearing in groups embedded in type IV continua. In most cases they show both absorption and emission ridges, the absorption having a slightly lower frequency than the emission. They are, most probably, manifestations of whistler-Langmuir wave interaction and they travel upwards along post flare loops (Kuijpers 1975). In a recent work (Bouratzis et […]

3D reconstruction of CME-driven shock-streamer interaction as a coronal magnetic field diagnostics
by S. Mancuso et al.*

2019-06-04 326 views

Coronal Mass Ejections (CMEs) expelled from the Sun can drive shocks that accelerate electrons which, in turn, produce electrostatic oscillations called Langmuir waves. These waves are then converted into escaping e.m. radiation, known as type II solar radio bursts, emitted near the fundamental and/or harmonic of the local electron plasma frequency. As shocks propagate outward from the Sun to regions of lower plasma density, type IIs appear in dynamic spectra […]

Variable Emission Mechanism of a Type IV Radio Burst
by D. Morosan et al.*

2019-04-23 351 views

Coronal mass ejections (CMEs) are sometimes accompanied by continuum emission at decimetric and metric wavelengths, called Type IV radio bursts. Of particular interest to determining CME properties are moving Type IV radio bursts, which are broadband radio sources moving outwards from the Sun. First studies suggested that moving Type IV bursts are emitted by synchrotron or gyro-synchrotron emitting electrons that are trapped inside CME loops (Dulk 1973). However, since their […]

Source Imaging of a Moving Type-IV Solar Radio Burst and its Role in Tracking Coronal Mass Ejection From the Inner to the Outer Corona
by Y. Chen et al.

2019-02-26 384 views

T-IV solar radio bursts are wideband continuum observed with dynamic spectrographs at metric to decametric wavelengths. They can be classified into static and moving ones, according to whether the sources remain basically static or move outward. The static ones are related to solar flares with frequencies extending up to GHz, while the moving ones (T-IVms) are related to coronal mass ejections (CMEs) with frequencies sometimes shifting to tens of MHz. […]

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