Solar Physics with the Square Kilometre Array
by A. Nindos et al.*

2019-08-13 304 views

Although solar physics is one of the most mature branches of astrophysics, the Sun confronts us with a large number of outstanding problems that are fundamental in nature.  These problems include the determination of the structure and dynamics of the solar atmosphere, the magnetic field evolution in the chromosphere and corona, coronal heating, the physics of impulsive energy release, energetic particle acceleration and transport, the physics of coronal mass ejections […]

Localized Microwave and EUV Bright Structures in an Eruptive Prominence
by J. Huang et al.*

2019-07-30 167 views

We study a solar eruptive prominence with flare/coronal mass ejection (CME) event by microwave and extreme ultraviolet (EUV) observations. Its evolution can be divided into three phases: slow rise, fast expansion, and ejection. In the slow-rise phase, the prominence continuously twists for more than one hour with a patch of bright emission appearing around the top. When the north leg interacts with the local small-size loops, the fast expansion is […]

Unsupervised Generation of High Dynamic Range Solar Images: A Novel Algorithm for Self-calibration of Interferometry Data
by Surajit Mondal et al.*

2019-07-16 177 views

Imaging the sun at radio wavelengths with high fidelity is an intrinsically hard problem. This stems from: a) the large range of angular scales on which the emission is present; b) the huge difference in brightness temperature associated with the various emission mechanisms which are responsible for radio emission; and c) high variability of solar emission on small temporal (<1s) and spectral (~kHz) scales. These together imply that the uv […]

Detection of Spike-like structures near the front of Type II radio bursts
by S. Armatas et al.*

2019-07-02 450 views

Type II solar radio bursts are the result of energetic electrons accelerated by a shock. This kind of burst appears on dynamic spectra as lanes which drift slowly from high to lower frequencies. Often, we observe a fundamental – harmonic structure, which sometimes exhibits a division on each band called band-split.  Fine structures are emissions with short duration and bandwidth embedded within all types of radio bursts and constitute a […]

Scaling-laws of Radio Spike Bursts and Their Constraints on New Solar Radio Telescopes
by Baolin Tan et al.

2019-06-18 323 views

Radio observation is one of the most important methods in solar physics and space science. Sometimes, it is almost the sole approach to observing physical processes such as the acceleration, emission, and propagation of non-thermal energetic particles, etc. Long-term observation and study have revealed that a strong solar radio burst is always composed of many small bursts with different time-scales. Among them, a radio spike burst is the smallest one, […]

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

2019-06-04 259 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 […]

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

2019-05-21 369 views

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 […]

High‐Frequency Communications Response to Solar Activity in September 2017 as Observed by Amateur Radio Networks
by Nathaniel A. Frissell

2019-05-07 266 views

Long before satellite communications, high frequency (HF, 3–30 MHz) radio was the primary method for long distance, over-the-horizon wireless communications. HF signals are able to travel long distances by refracting off of the ionosphere in what is known as “skip” or “skywave” propagation. Aside from a transmitter and receiver, no additional technological infrastructure is needed. Because of this, even in the modern age of space‐borne relays and widely distributed Internet availability, […]

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