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Although the surface of a magnetar is a source of bright thermal X-rays, its spectrum contains substantial non-thermal components. The X-ray emission is pulsed, with pulsed fractions that can be as high as ~ 70%. Several properties of…

Astrophysics · Physics 2011-02-11 Rodrigo Fernandez , Christopher Thompson

We investigated the intermittent energy-releasing processes by analyzing the long-period pulsations during a C2.8 flare on 2023 June 03. The C2.8 flare shows three successive and repetitive pulsations in soft X-ray (SXR) and…

Solar and Stellar Astrophysics · Physics 2024-08-05 Dong Li , Jianping Li , Jinhua Shen , Qiwu Song , Haisheng Ji , Zongjun Ning

The structure of electric current and magnetic helicity in the solar corona is closely linked to solar activity over the 11-year cycle, yet is poorly understood. As an alternative to traditional current-free "potential field"…

Solar and Stellar Astrophysics · Physics 2015-05-18 A. R. Yeates , J. A. Constable , P. C. H. Martens

Twisted coronal loops should be ubiquitous in the solar corona. Twisted magnetic fields contain excess magnetic energy, which can be released during magnetic reconnection, causing solar flares. The aim of this work is to investigate…

Solar and Stellar Astrophysics · Physics 2015-01-27 Mykola Gordovskyy , Philippa Browning , Eduard Kontar , Nicolas Bian

Standing long-period (with the periods longer than several minutes) oscillations in large hot (with the temperature higher than 3 MK) coronal loops have been observed as the quasi-periodic modulation of the EUV and microwave intensity…

Solar and Stellar Astrophysics · Physics 2016-06-15 Sanjay Kumar , V. M. Nakariakov , Y. -J. Moon

We discuss Electron Cyclotron Maser Emission (ECME), observed in the form of highly circularly polarized pulses, from a few hot magnetic stars. This emission is one of the manifestations of stellar wind-magnetic field interaction. With the…

Solar and Stellar Astrophysics · Physics 2019-12-20 Barnali Das , Poonam Chandra , Gregg A. Wade , Matt E. Shultz , James Sikora

Accreting X-ray pulsars provide us with laboratories for the study of extreme gravitational and magnetic fields, hence accurate descriptions of their observational properties contribute to our understanding of this group of objects. We aim…

Magnetic fields of exoplanets are important in shielding the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both…

Earth and Planetary Astrophysics · Physics 2020-05-27 Yang Gao , Lei Qian , Di Li

We test the synchrotron emission scenario for the very bright gamma-ray flare of blazar 3C 279 observed in 2015 June using time-dependent numerical simulations. A bulk Lorentz factor as high as 100 can bring the synchrotron maximum energy…

High Energy Astrophysical Phenomena · Physics 2020-02-19 Katsuaki Asano , Masaaki Hayashida

We report on the properties of type II radio bursts observed by the Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft over the past two solar cycles. We confirm that the associated coronal mass ejections (CMEs) are fast…

Solar and Stellar Astrophysics · Physics 2018-10-29 N. Gopalswamy , P. Mäkelä

Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure…

Solar and Stellar Astrophysics · Physics 2015-05-28 Durgesh Tripathi , James A. Klimchuk , Helen E. Mason

There is considerable observational evidence of implosion of magnetic loop systems inside solar coronal active regions following high energy events like solar flares. In this work, we propose that such collapse can be modeled in three…

Solar and Stellar Astrophysics · Physics 2017-12-27 Aveek Sarkar , Bhargav Vaidya , Soumitra Hazra , Jishnu Bhattacharyya

We report for the first time the detection of thermal free-free emission from post-flare loops at 34GHz in images from the Nobeyama Radioheliograph (NoRH). We studied 8 loops, 7 of which were from regions with extremely strong coronal…

Solar and Stellar Astrophysics · Physics 2024-06-24 Costas E. Alissandrakis , Gregory D. Fleishman , Viktor V. Fedenev , Stephen M. White , Alexander T. Altyntsev

We present a systematic fit of a model of resonant cyclotron scattering (RCS) to the X and soft gamma-ray data of four magnetars, including anomalous X-ray pulsars, and soft gamma repeaters. In this scenario, non-thermal magnetar spectra in…

High Energy Astrophysical Phenomena · Physics 2010-04-30 D. Gotz , N. Rea , S. Zane , R. Turolla , M. Lyutikov

We present a complete solution to the cyclotron-synchrotron radiation due to an isotropic distribution of electrons moving in a magnetic field. We make no approximations in the calculations other than artificially broadening the harmonics…

Astrophysics · Physics 2009-10-28 Rohan Mahadevan , Ramesh Narayan , Insu Yi

We propose a simple physical picture for the generation of coherent radio emission in the axisymmetric pulsar magnetosphere that is quite different from the canonical paradigm of radio emission coming from the magnetic polar caps. In this…

High Energy Astrophysical Phenomena · Physics 2009-11-13 Ioannis Contopoulos

Nonthermal electrons accelerated in solar flares produce electromagnetic emission in two distinct, highly complementary domains - hard X-rays (HXRs) and microwaves (MWs). This paper reports MW imaging spectroscopy observations from the…

Solar and Stellar Astrophysics · Physics 2020-04-29 Natsuha Kuroda , Gregory D. Fleishman , Dale E. Gary , Gelu M. Nita , Bin Chen , Sijie Yu

Large coronal loops around one solar radius in altitude are an important connection between the solar wind and the low solar corona. However, their plasma properties are ill-defined as standard X-ray and UV techniques are not suited to…

Solar and Stellar Astrophysics · Physics 2023-02-01 Jinge Zhang , Hamish A. S. Reid , Vratislav Krupar , Pietro Zucca , Bartosz Dabrowski , Andrzej Krankowski

The aim of the present paper is to use quasi-periodic oscillations in hard X-rays (HXRs) of solar flares as a diagnostic tool for investigation of impulsive electron acceleration. We have selected a number of flares which showed…

Solar and Stellar Astrophysics · Physics 2015-05-13 J. Jakimiec , M. Tomczak

Context: Solar flare hard X-rays (HXRs) are thought to be produced by nonthermal coronal electrons stopping in the chromosphere, or remaining trapped in the corona. The collisional thick target model (CTTM) predicts that sources produced by…

Solar and Stellar Astrophysics · Physics 2015-06-15 A. O'Flannagain , P. Gallagher , J. Brown , R. Milligan , G. Holman