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We present low-frequency (80-240 MHz) radio imaging of type III solar radio bursts observed by the Murchison Widefield Array (MWA) on 2015/09/21. The source region for each burst splits from one dominant component at higher frequencies into…

Solar and Stellar Astrophysics · Physics 2018-01-10 Patrick I. McCauley , Iver H. Cairns , John Morgan , Sarah E. Gibson , James C. Harding , Colin Lonsdale , Divya Oberoi

The Murchison Widefield Array (MWA) recorded \cite{Mondal-2020} impulsive radio events in the quiet solar corona at frequencies 98, 120, 132, and 160 MHz. We propose that these radio events are the direct manifestation of dark matter…

High Energy Astrophysical Phenomena · Physics 2021-01-04 Shuailiang Ge , Md Shahriar Rahim Siddiqui , Ludovic Van Waerbeke , Ariel Zhitnitsky

Low-frequency (80-240 MHz) radio observations of the solar corona are presented using the Murchison Widefield Array (MWA), and several discoveries are reported. The corona is reviewed, followed by chapters on Type III bursts and…

Solar and Stellar Astrophysics · Physics 2019-12-05 Patrick I. McCauley

Quasi-periodic pulsations (QPPs) at sub-second periods are frequently detected in the time series of X-rays during stellar flares. However, such rapid pulsations are rarely reported in the hard X-ray (HXR) emission of the small solar flare.…

Solar and Stellar Astrophysics · Physics 2025-06-18 Dong Li

The solar corona is a highly-structured plasma which can reach temperatures of more than ~2 MK. At low frequencies (decimetric and metric wavelengths), scattering and refraction of electromagnetic waves are thought to considerably increase…

Recurrent, arc-shaped intensity disturbances were detected by EUV channels in an active region. The fronts were observed to propagate along a coronal loop bundle rooted in a small area within a sunspot umbra. Previous works have linked…

Solar and Stellar Astrophysics · Physics 2022-11-02 M. V. Sieyra , S. Krishna Prasad , G. Stenborg , E. Khomenko , T. Van Doorsselaere , A. Costa , A. Esquivel , J. M. Riedl

Quasi-periodic pulsations (QPP) are usually found in the light curves of solar and stellar flares, they carry the features of time characteristics and plasma emission of the flaring core, and could be used to diagnose the coronas of the Sun…

Solar and Stellar Astrophysics · Physics 2020-01-08 Ding Yuan , Song Feng , Dong Li , Zhongjun Ning , Baolin Tan

A common feature of electromagnetic emission from solar flares is the presence of intensity pulsations that vary as a function of time. Known as quasi-periodic pulsations (QPPs), these variations in flux appear to include periodic…

Solar and Stellar Astrophysics · Physics 2021-04-14 Brendan P. Clarke , Laura A. Hayes , Peter T. Gallagher , Shane A. Maloney , Eoin P. Carley

Slow magnetoacoustic waves represent an important tool for probing the solar coronal plasma. We quantitatively assess the applicability of the weak thermal conduction theory to coronal seismology by slow waves. We numerically model the…

Solar and Stellar Astrophysics · Physics 2022-11-23 Dmitrii Y. Kolotkov

During non-flaring times, the radio flux of the Sun at the wavelength of a few centimeters to several tens of centimeters mostly originates from the thermal bremsstrahlung emission, very similar to the EUV radiation. Owing to such a…

Solar and Stellar Astrophysics · Physics 2020-03-11 Z. F. Li , S. H. Hua , X. Cheng , M. D. Ding

In this paper, we report the observed temporal correlation between extreme-violet (EUV) emission and magneto-acoustic oscillations in a EUV moss region, which is the footpoint region only connected by magnetic loops with million-degree…

Solar and Stellar Astrophysics · Physics 2021-06-02 Parida Hashim , Zhenxiang Hong , Haisheng Ji , Jinhua Shen , Kaifan Ji , Wenda Cao

The X-ray quasi-periodic oscillation (QPO) is a remarkable form of variability in systems of compact object accretion. RE J1034+396, harboring the most significant X-ray QPO in active galactic nuclei (AGNs), is the most noteworthy source…

High Energy Astrophysical Phenomena · Physics 2025-03-10 Ruisong Xia , Hao Liu , Yongquan Xue

High-frequency wave phenomena present a great deal of interest as one of the possible candidates to contribute to the energy input required to heat the corona as a part of the AC heating theory. However, the resolution of imaging…

Solar and Stellar Astrophysics · Physics 2023-04-05 Elena Petrova , Norbert Magyar , Tom Van Doorsselaere , David Berghmans

Millihertz quasi-periodic oscillations (mHz QPOs) observed in neutron-star low-mass X-ray binaries (NS LMXBs) are generally explained as marginally stable thermonuclear burning on the neutron star surface. We report the discovery of mHz…

High Energy Astrophysical Phenomena · Physics 2020-10-28 Kaho Tse , Duncan K. Galloway , Yi Chou , Alexander Heger , Hung-En Hsieh

We report on the detection (10 \sigma) of 917 events of long-period (3 to 16 hours) intensity pulsations in the 19.5 nm passband of the SOHO Extreme ultraviolet Imaging Telescope. The data set spans from January 1997 to July 2010, i.e the…

Solar and Stellar Astrophysics · Physics 2014-03-05 F. Auchère , K. Bocchialini , J. Solomon , E. Tison

Microflares are small dynamic signatures observed in X-ray and extreme-ultraviolet channels. Because of their impulsive emission enhancements and wide distribution, they are thought to be closely related to coronal heating. By using the…

Solar and Stellar Astrophysics · Physics 2015-04-01 Fayu Jiang , Jun Zhang , Shuhong Yang

Solar radio U-bursts are generated by electron beams traveling along closed magnetic loops in the solar corona. Low-frequency ($<$ 100 MHz) U-bursts serve as powerful diagnostic tools for studying large-sized coronal loops that extend into…

Solar and Stellar Astrophysics · Physics 2024-02-08 Jinge Zhang , Hamish A. S. Reid , Eoin Carley , Laurent Lamy , Pietro Zucca , Peijin Zhang , Baptiste Cecconi

M-dwarf flare stars like AD Leo are laboratories for studying intense magnetic activities. The coherent radio bursts they produce are powerful probes of stellar coronal plasma and magnetic fields. In this study, we present high-resolution…

Solar and Stellar Astrophysics · Physics 2026-04-02 Wenjie Zou , Hui Tian , Jiale Zhang , Yuhang Gao

This work consists of two parts: the first devoted to the study of the heating of the magnetically confined Solar Corona, and the second to the acceleration of the Slow Solar Wind. Direct 3D reduced MHD simulations are presented. They model…

Solar and Stellar Astrophysics · Physics 2010-01-13 A. F. Rappazzo

High resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of…

Solar and Stellar Astrophysics · Physics 2023-11-01 Paola Testa , Helle Bakke , Luc Rouppe van der Voort , Bart De Pontieu