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We present a detailed examination on the coronal nonthermal emissions during the preflare phase of the X4.8 flare that occurred on 2002 July 23. The microwave (17 GHz and 34 GHz) data obtained with Nobeyama Radioheliograph, at Nobeyama…

Solar and Stellar Astrophysics · Physics 2011-02-11 Ayumi Asai , Hiroshi Nakajima , Masumi Shimojo , Takaaki Yokoyama , Satoshi Masuda , Sam Krucker

Decades of astrophysical observations have convincingly shown that soft X-ray (SXR; ~0.1--10 keV) emission provides unique diagnostics for the high temperature plasmas observed in solar flares and active regions. SXR observations critical…

Instrumentation and Methods for Astrophysics · Physics 2017-01-04 Amir Caspi , Albert Y. Shih , Harry P. Warren , Marek Stęślicki , Janusz Sylwester

The solar corona is full of dynamic phenomena, e.g., solar flares, micro flares in active regions, jets in coronal holes and in the polar regions, X-ray bright points in quiet regions, etc. They are accompanied by interesting physical…

Solar and Stellar Astrophysics · Physics 2017-06-15 Noriyuki Narukage , Shin-nosuke Ishikawa , Tomoko Kawate , Shinsuke Imada , Taro Sakao

This review surveys the statistics of solar X-ray flares, emphasising the new views that RHESSI has given us of the weaker events (the microflares). The new data reveal that these microflares strongly resemble more energetic events in most…

Solar and Stellar Astrophysics · Physics 2011-09-01 I. G. Hannah , H. S. Hudson , M. Battaglia , S. Christe , J. Kasparova , S. Krucker , M. R. Kundu , A. Veronig

Hard X-ray (HXR) spectroscopy is the most direct method of diagnosing energetic electrons in solar flares. Here we present a technique which allows us to use a single HXR spectrum to determine an effectively stereoscopic electron energy…

Astrophysics · Physics 2009-11-11 Eduard P. Kontar , John C. Brown

Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares,…

Solar and Stellar Astrophysics · Physics 2014-06-25 Amir Caspi , James M. McTiernan , Harry P. Warren

Recent measurements of vertical extents and positions of the chromospheric hard X-ray (HXR) flare sources based on Ramaty High-Energy Spectroscopic Imager (RHESSI) observations show a significant inconsistency with the theoretical…

Solar and Stellar Astrophysics · Physics 2016-12-07 Z. Moravec , M. Varady , J. Kasparova , D. Kramolis

Sudden jets of collimated plasma arise from many locations on the Sun, including active regions. The magnetic field along which a jet emerges is often open to interplanetary space, offering a clear "escape route" for any flare-accelerated…

Solar and Stellar Astrophysics · Physics 2018-11-07 Lindsay Glesener , Gregory D. Fleishman

The aim of this paper is to investigate the spatial structure of the impulsive phase hard X-ray emission from solar flares. This work is motivated by the YOHKOH and the forthcoming HESSI observations. Summarizing past results, it is shown…

Astrophysics · Physics 2009-10-31 Vahe Petrosian , Timothy Q. Donaghy

RHESSI observations of elementary flare bursts are presented. These solar flare elements are distinct emission peaks of a duration of some tens of seconds present in the hard X-ray light curves. They are characterized by consistent…

Astrophysics · Physics 2007-05-23 Paolo C. Grigis , Arnold O. Benz

A M-class behind-the-limb solar flare on 1 May 2013 (SOL2013-05-01T02:32), accompanied by a ($\sim$ 400 km/s) CME was observed by several space-based observatories with different viewing angles. We investigated the RHESSI-observed occulted…

The aim of this paper is to demonstrate the effect of turbulent background density fluctuations on flare-accelerated electron transport in the solar corona. Using the quasi-linear approximation, we numerically simulated the propagation of a…

Solar and Stellar Astrophysics · Physics 2015-06-12 I. G. Hannah , E. P. Kontar , H. A. S. Reid

X-ray observations of solar flares routinely reveal an impulsive high-energy and a gradual low-energy emission component, whose relationship is one of the key issues of solar flare study. The gradual and impulsive emission components are…

Solar and Stellar Astrophysics · Physics 2015-05-20 Jingnan Guo , Siming Liu , Lyndsay Fletcher , Eduard P. Kontar

Coronal Jets are transitory small-scale eruptions omnipresent in solar observations. Active regions jets produce significant perturbations on the ambient solar atmosphere and are believed to be generated by microflare reconnection. Multiple…

Solar and Stellar Astrophysics · Physics 2019-03-13 Alin Razvan Paraschiv , Alina Donea

We present new RHESSI upper limits in the 3-200 keV energy range for solar hard X-ray emission in the absence of flares and active regions, i.e. the quiet Sun, using data obtained between July 2005 and April 2009. These new limits,…

Solar and Stellar Astrophysics · Physics 2015-05-19 I. G. Hannah , H. S. Hudson , G. J. Hurford , R. P. Lin

We study the association of solar flares with coronal mass ejections (CMEs) during the deep, extended solar minimum of 2007-2009, using extreme-ultraviolet (EUV) and white-light (coronagraph) images from the {\it Solar Terrestrial Relations…

Solar and Stellar Astrophysics · Physics 2015-06-16 N. V. Nitta , M. J. Aschwanden , S. L. Freeland , J. R. Lemen , J. -P. Wülser , D. M. Zarro

We compare the characteristics of flare-accelerated energetic electrons at the Sun with those injected into interplanetary space. We have identified 17 energetic electron events well-observed with the SEPT instrument aboard STEREO which…

Solar and Stellar Astrophysics · Physics 2021-10-20 Nina Dresing , A. Warmuth , F. Effenberger , K. -L. Klein , S. Musset , L. Glesener , M. Brüdern

Solar flare hard X-rays (HXRs) are produced as bremsstrahlung when an accelerated population of electrons interacts with the dense chromospheric plasma. HXR observations presented by using the Ramaty High-Energy Solar Spectroscopic Imager…

Solar and Stellar Astrophysics · Physics 2014-11-20 A. O'Flannagain , J. C. Brown , P. T. Gallagher

Data obtained in the framework of the INTERBALL-Tail Probe (1995-2000) and RHESSI (from 2002 to the present) projects have revealed variations in the X-ray intensity of the solar corona in the photon energy range of 2-15 keV during the…

High Energy Astrophysical Phenomena · Physics 2019-04-08 I. K. Mirzoeva , S. G. Chefranov

The collisional thick target model (CTTM) of solar hard X-ray (HXR) bursts has become an almost 'Standard Model' of flare impulsive phase energy transport and radiation. However, it faces various problems in the light of recent data,…

Solar and Stellar Astrophysics · Physics 2015-05-14 J. C. Brown , R. Turkmani , E. P. Kontar , A. L. MacKinnon , L. Vlahos
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