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Coronal loops reveal crucial information about the nature of both coronal magnetic fields and coronal heating. The shape of the corresponding flux tube cross section and how it varies with position are especially important properties. They…
The spectrum of cyclotron radiation produced by electrons with a strongly anisotropic velocity distribution is calculated taking into account higher harmonics. The motion of the electrons is assumed to be ultrarelativistic along the…
The solar corona is much hotter than the photosphere and chromosphere, but the physical mechanism responsible for heating the coronal plasma remains unidentified yet. The thermal microwave emission, which is produced in strong magnetic…
Nonthermal sources located above bright flare arcades, referred to as the "above-the-loop-top" sources, have been often suggested as the primary electron acceleration site in major solar flares. The X8.2 limb flare on 2017 September 10…
The accelerated electrons during solar flares produce radio bursts and nonthermal X-ray signatures. The quasi-periodic pulsations (QPPs) and fine structures in spatial-spectral-temporal space in radio bursts depend on the emission mechanism…
Recent observations from {\em RHESSI} have revealed that the number of non-thermal electrons in the coronal part of a flaring loop can exceed the number of electrons required to explain the hard X-ray-emitting footpoints of the same flaring…
Persistent activity of magnetars is associated with electric discharge that continually injects relativistic particles into the magnetosphere. Large active magnetic loops around magnetars must be filled with outflowing particles that…
Two coherent radio emission mechanisms operate in stellar coronae: plasma emission and cyclotron emission. They directly probe the electron density and magnetic field strength respectively. Most stellar radio detections have been made at…
Electromagnetic radiation at higher harmonics of the plasma frequency ($\omega \sim n\omega_{pe}, n > 2$) has been occasionally observed in type II and type III solar radio bursts, yet the underlying mechanism remains undetermined. Here we…
Electron resonant scattering by high-frequency electromagnetic whistler-mode waves has been proposed as a mechanism for solar wind electron scattering and pre-acceleration to energies that enable them to participate in shock drift…
Solar flares and coronal mass ejections (CMEs) can accelerate electrons, causing bursts such as type IV emissions in the solar radio continuum. Although radio spectroscopy is a powerful diagnostic tool for the corona, the origin and…
This paper investigates the incidence of coherent emission in solar radio bursts, using a revised catalog of 3800 solar radio bursts observed by the Nobeyama Radio Polarimeters from 1988 to 2023. We focus on the 1.0 and 2.0 GHz data, where…
We investigate the evolution of coronal loop emission in the context of the coronal magnetic field topology. New modeling techniques allow us to investigate the magnetic field structure and energy release in active regions. Using these…
Recent observations of the polarisation of the optical pulses from the Crab pulsar motivated detailed comparative studies of the emission predicted by the polar cap, the outer gap and the two-pole caustics models. In this work, we study the…
Coronal loops generally trace magnetic lines of force in the upper solar atmosphere. Understanding the loop morphology and its temporal evolution has implications for coronal heating models that rely on plasma heating due to reconnection at…
Coronal Mass Ejections (CMEs) are believed to be effective in producing shocks in the solar corona and the interplanetary space. One of the important signatures of shocks and shock acceleration are Type II solar radio bursts that drift with…
Solar flares are associated with intense soft X-ray emission generated by the hot flaring plasma. Kink unstable twisted flux-ropes provide a source of magnetic energy which can be released impulsively and account for the flare plasma…
The excess temperature of the solar corona over the photosphere poses a challenge. Multiple energetic events contribute to maintaining the corona at such high temperatures. The energy released in different events can vary across several…
Data from recent numerical simulations of the solar corona and transition region are analysed and the magnetic field connection between the low corona and the photosphere is found to be close to that of a potential field. The fieldline to…
Coronal mass ejection (CME) often produces a soft X-ray (SXR) flare associated with the low-coronal reconnection and a type-II radio burst associated with an interplanetary (IP) CME-shock. SXR flares and type-II bursts outshine the…