Low Frequency Array (LOFAR)

On the Source Position and Duration of a Solar Type III Radio Burst Observed by LOFAR
by P. Zhang et al.*

2020-01-21

Type III radio bursts are generated by non-thermal electron beams propagating through the solar corona and interplanetary space. In dynamic spectra, the flux of solar type III radio bursts have a time profile of rising and decay phases at a given frequency, which has been actively studied since the 1970s. There are several factors that may contribute to the observed duration of a type III radio burst: 1) The velocity […]

First imaging spectroscopy observations of puzzling solar drift pair bursts
by A. Kuznetsov and E. Kontar

2019-12-17

Drift pairs are a rare and puzzling type of solar radio emission, firstly identified by Roberts (1958). They occur at low frequencies (~10-100 MHz) and look like two parallel frequency-drifting narrow-band stripes separated in time. The drift rates (typically ~2-8 MHz/s) are intermediate between those of type II and type III bursts; both positive and negative frequency drifts are observed. The most enigmatic characteristic of drift pair bursts is that […]

Anisotropic radio-wave scattering in the solar corona
Nicolina Chrysaphi et al.*

2019-11-26

Solar radio emission is produced in the turbulent medium of the solar atmosphere, and its observed properties (source position, size, time profile, polarization, etc.) are significantly affected by the propagation of the radio waves from the emitter to the observer. Scattering of radio waves on random density irregularities has long been recognized as an important process for the interpretation of radio source sizes (e.g., Steinberg et al. 1971), positions (e.g., […]

The effect of scattering on the apparent positions of solar radio sources observed by LOFAR
by Mykola Gordovskyy

2019-05-21

Radio sources observed in the decametric range during type II and type III solar radio bursts are believed to be produced by coherent plasma emission due to electrostatic plasma oscillations induced by propagating suprathermal electrons (e.g. Ginzburg & Zhelezniakov 1958). This type of emission is a valuable tool for observational diagnostics of the upper corona. Produced at the local plasma frequency, $f_{pe}\rm{[kHz]}= 8.93 (n_e\rm{[cm}^{-3}\rm{]})^{-1/2}$ or its harmonic, plasma emission can reveal […]

Remote sensing the coronal magnetic field using solar S-bursts B. Clarke et al.*

2019-04-09

Solar activity is often accompanied by solar radio emission. At low frequencies, radio bursts with short durations of <1 s, known as solar S-bursts, have been identified. These intriguing, low frequency bursts were first identified by McConnell (1982) who named them solar S-bursts, owing to their similarity to Jovian S-bursts: the S stands for short or storm. S-bursts appear as narrow tracks on a dynamic spectrum that usually drift from […]

Coronal Mass Ejection-driven Type II solar radio burst structure with LOFAR and radio-wave scattering
by Nicolina Chrysaphi et al.*

2019-01-29

Coronal Mass Ejections (CMEs) are often viewed as the major drivers of space weather disturbances in the Sun-Earth system. Shocks driven by CMEs can excite radio emissions characterised by a slow frequency drift across dynamic spectra. These radio emissions are known as Type II solar radio bursts and can consist of two bands with a frequency ratio of 1:2. Each of these bands can split into two thinner sub-bands, a […]

Shock location and CME 3-D reconstruction of a solar type II radio burst with LOFAR
by P. Zucca et al.*

2018-10-30

Type II radio bursts are the result of shocks in the solar atmosphere and they can be observed ranging from sub-metric to kilometric wavelengths (~400 MHz to ~0.4 MHz). Coronal mass ejections initiate most of the metric type II (m-type II) bursts. The region of a CME responsible for driving the shock might be different for each event and has not yet been comprehensively identified. Multiple scenarios have been suggested, […]

Modulation of radio emission, fast magnetoacoustic waves and magnetic field measurements in the solar corona with LOFAR
by Kolotkov et al*

2018-08-21

Fast magnetoacoustic wave trains are a promising seismological probe of the corona, revealing the magnetic connectivity and providing the estimation of the absolute value of the coronal magnetic field. Low-frequency radio observations allow for the detection of fast wave trains in middle and upper corona, above the field-of-view of EUV imagers and spectrographs, via the modulation of the radio emission by the variations of the electron concentration. We present the […]

1 2 3

CESRA webpage © 2023 | Made using WordPress Theme by MH Themes