Flares detected in ALMA single-dish images
by I. Skokic et al

2022-12-06 102 views

The (sub)millimeter radiation of solar flares, explosive events detected as brightenings across the electromagnetic spectrum, is poorly understood (Krucker et al. 2013). The major limit of the previous >100 GHz observations was spatial resolution, impeding the combination with observations at other wavelengths. The Atacama Large Millimeter-submillimeter Array (ALMA) offers sufficient resolution for the first time. Shimizu et al. (2021) reported a microflare observed in interferometric mode. However, used as an […]

Third and fourth harmonics of electromagnetic emissions by a weak beam in a solar wind plasma with random density fluctuations by C. Krafft

2022-11-22 63 views

Electromagnetic emissions at the third harmonic of the plasma frequency $\omega _{p}$ have been reported during the occurrence of type II and type III solar radio bursts (e.g. Zlotnik 1978, Zlotnik et al. 1998, Cairns; 1986), even if rarely and sometimes controversially. Recently the Wind spacecraft detected several events exhibiting third harmonic emissions in interplanetary type III bursts observed locally near 1 AU (Reiner and MacDowald; 2019). For the first […]

Characteristics of stripes-pattern radio-emission sources by Khaled Alielden

2022-10-18 102 views

Investigating the generation mechanism for the stripes-pattern radio spectra is important to understand the dynamics of non-thermal electrons in several astronomical objects, including the Sun, Jupiter, and the Crab Pulsar. A new analytical study is carried out to identify the plasma characteristics of fiber- and zebra-pattern emission sources without an underlying density or magnetic model. The study suggests that the plasma condition of the source region for zebra pattern emission […]

Narrowband Spikes Observed During the 13 June 2012 Flare in the 800 – 2000 MHz Range by Marian Karlicky et al

2022-09-06 111 views

The solar radio spikes can provide detailed information about plasma processes in solar flares on kinetic scales. Among them, the decimetric spikes belong to the most interesting ones because they are recorded in some cases close to the starting frequency of Type-III bursts and in relation to hard X-ray emissions. Stepanov et al. (1999) and Bárta and Karlický (2001) presented models where spike frequencies correspond to those of the upper-hybrid […]

Tackling the Unique Challenges of Low-frequency Solar Polarimetry with the Square Kilometre Array Low Precursor: The Algorithm by Devojyoti Kansabanik et al

2022-08-23 88 views

The solar corona comprises hot magnetized plasma. Coronal magnetic fields are well known to be one of the crucial parameters determining the physics of the solar corona and are vital drivers of Space Weather. Despite the fact that the importance of coronal magnetic fields has been recognised for a long, in practice, they remain rather hard to measure. The polarization properties of coronal emission at low radio frequencies can, in […]

Langmuir-Slow Extraordinary Mode Magnetic Signature Observations with Parker Solar Probe
by A. Larosa et al

2022-05-03 128 views

Langmuir-Slow extraordinary mode (L-SE) waves have been routinely observed in the Solar wind and in Earth’s electron foreshock since the early age of the space exploration. They are intimately connected to the plasma emission mechanism for the type III and type II radio emissions. In fact, the generally accepted scenario is that L-SE waves are mode-converted to freely propagating electromagnetic emission at the plasma frequency. However,  the details of the […]

LOFAR size and shape measurements of solar metric radio burst sources
by Gordovskyy et al

2022-04-19 226 views

The plasma density and magnetic field in the upper solar corona and inner heliosphere are not sufficient to produce detectable bremsstrahlung hard X-ray or gyrosynchrotron microwave emissions, making metric and decametric coherent radio emissions the only tool for probing energetic electrons in these layers of the solar atmosphere (e.g. McLean & Labrum 1985; Pick & Vilmer 2008 as reviews). This source of information is vital to understanding the underlying mechanisms […]

Radio, X-ray and extreme-ultraviolet observations of weak energy releases in the ‘quiet’ Sun
by Ramesh et. al.

2021-10-26 136 views

Small scale energy releases on the Sun e.g., flaring bright points, active region transient brightenings, etc. have been studied using X-ray and radio observations. The observations of low frequency radio type III bursts in associated with X-ray bright point flares (Kundu et. al. 1980) and coronal X-ray jets (Aurass et. al. 1994) indicated that the latter are capable of accelerating particles to non-thermal energies, as well as producing the heated […]

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