Radio measurements of coronal magnetic fields in fan-spine configurations on the Sun by B. Ryabov and A. Vrublevskis

2023-06-06 73 views

We are striving for more accurate coronal magnetography based on changes in radio polarization as microwaves cross magnetic field lines at nearly right angles. The theory of using quasi-transverse propagation for coronal field measurements includes weak dependence on two parameters: plasma density $N_e$ and the magnetic field divergence $L_d$ (see Alissandrakis and Gary, 2021 for a review). We evaluate coronal plasma density from local differential emission measure computed from the […]

Automated Detection and Statistical Study of Solar Radio Spikes by P.R. Lv et al

2023-04-26 102 views

Solar radio spikes’ most typical observational features are their short duration and narrow bandwidth. They appear on the solar radio dynamic spectrogram as a large number of narrow-band type-III bursts, spikes, dots, sub-second clumps, groups, chains, and other narrow-band structures from decimeter to decameter wavelengths (Feng et al.(2018), Tan et al.(2019)). We have improved the YOLOv5s network model for these characteristics by adding inclined bounding frames and attention and feature […]

Solar Radio Spikes and Type IIIb Striae Manifestations Triggered by a Coronal Mass Ejection by Clarkson et al

2023-04-11 245 views

Radio bursts are frequently emitted in the outer solar corona due to the acceleration of energetic electrons in solar flares and coronal mass ejections (CME). The shortest observed bursts are radio spikes, which have narrow spectral widths and are emitted over decades in frequency. Despite being studied for many years, imaging observations are sparse and restricted to localisation of the emission at decimetre frequencies (e.g. Benz, 2002). Recently, LOw Frequency […]

Temporal and Spatial Association Between Microwaves and Type III Bursts in the Upper Corona by Altyntsev et al.

2023-03-28 152 views

One important task connected with the corona heating problem is exploring the physical mechanisms that produce, accelerate, and transport energetic particles in the upper corona. The magnetic connectivity between the sources of meter emission in the upper corona and electron acceleration sites in low corona are studied using the temporal correlation between hard X-ray (HXR) bursts and type III emission (Kane 1972; Aschwanden et al. 1995; Reid & Vilmer 2017). […]

Solar coronal density turbulence and magnetic field strength at the source regions of two successive metric type II radio bursts by Ramesh et. al.

2023-03-14 137 views

Solar type II radio bursts appear in the spectrograph records as slowly drifting emission lanes from high to low frequencies. They are due to plasma oscillations caused by the electrons accelerated at the MHD shocks propagating outward in the solar atmosphere (Nelson et al. 1985, Mann et al. 1995). The plasma emission in a magnetic field gets split as ordinary ($O$) and extraordinary ($X$) modes. Since the propagation characteristics of […]

The frequency ratio and time delay of fundamental and harmonic components in solar radio bursts by X. Chen et al

2023-02-28 241 views

Solar radio bursts generated through the plasma emission mechanism produce radiation near the local plasma frequency (fundamental emission, hereafter, F) and double the plasma frequency (harmonic, hereafter, H). While the theoretical ratio of these two frequencies is close to 2, simultaneous observations give ratios ranging from 1.6 to 2, suggesting either a ratio different from 2, a delay of the F emission, or both. Observations suggest that a delayed F […]

The Radial Variation of the Solar Wind Turbulence Spectra near the Kinetic Break Scale from Parker Solar Probe Measurements, by Lotz et al

2023-02-14 107 views

The Parker Solar Probe (PSP) has enabled unprecedented opportunity to study the plasma and magnetic field properties of the solar wind from near the Earth (~1 au radial distance r) to very close to the sun (r < 0.1 au). We are interested in the turbulence characteristics of the solar wind and how it evolves from close to the sun to far away. This information is crucial to the understanding […]

Special issue “Recent progress in the physics of the Sun and heliosphere”, by E. Kontar and I. Ballai

2023-02-10 205 views

The present Special Issue published in Advances of Space Research contains a collection of peer-reviewed contributions that builds on the recent observational and theoretical advances, surveying the existing knowledge in reconnecting magnetic fields, flares and plasma heating, the generation, evolutions and dynamics of small-scale solar jets, dynamics in various layers of the solar atmosphere, recent advances in coronal spectroscopy and the evolution of the solar wind inspired by European Solar […]

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