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The excess broadening of high-temperature spectral lines, long observed near the tops of flare arcades, is widely considered to result from magnetohydrodynamic (MHD) turbulence. According to different theories, plasma turbulence is also…

Solar and Stellar Astrophysics · Physics 2024-07-18 William Ashfield , Vanessa Polito , Sijie Yu , Hannah Collier , Laura Hayes

Investigate particle acceleration and heating in a solar microflare. In a microflare with non-thermal emission to remarkably high energies ($>50$ keV), we investigate the hard X-rays with RHESSI imaging and spectroscopy and the resulting…

Astrophysics · Physics 2010-09-17 I. G. Hannah , S. Krucker , H. S. Hudson , S. Christe , R. P. Lin

This study investigates the statistical behavior of plasma properties during Hot Onset Precursor Events (HOPEs) of solar flares and evaluates their potential for improving flare nowcasting. Two datasets are analyzed: (a) new Soft X-Ray…

Solar and Stellar Astrophysics · Physics 2025-09-08 Anant Telikicherla , Thomas N. Woods , Bennet D. Schwab

Microflares are energetically smaller versions of solar flares, demonstrating the same processes of plasma heating and particle acceleration. However, it remains unclear down to what energy scales this impulsive energy release continues,…

Solar and Stellar Astrophysics · Physics 2024-02-09 Kristopher Cooper , Iain G. Hannah , Lindsay Glesener , Brian W. Grefenstette

The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft observed flare footpoint regions coincident with a surge for a M3.7 flare observed on 25 September 2011 at N12 E33 in active region 11302. The flare was observed in…

Solar and Stellar Astrophysics · Physics 2015-10-30 George A. Doschek , Harry P. Warren , Brian R. Dennis , Jeffrey W. Reep , Amir Caspi

On October 3rd, 2024, the Sun emitted an X9.0-class flare from active region NOAA 13842. The event was recorded by multiple space-based instruments, beginning hours before the eruption, granting a unique opportunity to provide insight into…

Solar and Stellar Astrophysics · Physics 2026-05-28 Louis Seyfritz , Maria Kazachenko , Ryan French

We compare time variations of the H$\alpha$ and X-ray emissions observed during the pre-impulsive and impulsive phases of the C1.1-class solar flare on 21 June 2013 with those of plasma parameters and synthesized X-ray emission from a…

Solar and Stellar Astrophysics · Physics 2017-10-04 R. Falewicz , K. Radziszewski , P. Rudawy , A. Berlicki

We analyze the spectra of high temperature \fexxiv~lines observed by \emph{Hinode}/EIS during the impulsive phase of the X8.3--class flare on September 10, 2017. The line profiles are broad, show pronounced wings, and clearly depart from a…

Solar and Stellar Astrophysics · Physics 2018-09-05 Vanessa Polito , Jaroslav Dudík , Jana Kašparová , Elena Dzifčáková , Katharine K. Reeves , Paola Testa , Bin Chen

On the 29 March 2014 NOAA active region (AR) 12017 produced an X1 flare which was simultaneously observed by an unprecedented number of observatories. We have investigated the pre-flare period of this flare from 14:00 UT until 19:00 UT…

Solar and Stellar Astrophysics · Physics 2017-03-08 M. M. Woods , L. K. Harra , S. A. Matthews , D. H. Mackay , S. Dacie , D. M. Long

In the classical flare picture, hard X-ray emission from the chromosphere is succeeded by soft-X-ray emission from hot plasma in the flare loop, the soft X-ray emission being a direct consequence of the impact of the non-thermal particle…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. Battaglia , L. Fletcher , A. O. Benz

In some flares the thermal component appears much earlier than the nonthermal component in X-ray range. Using sensitive microwave observations we revisit this finding made by Battaglia et al. (2009) based on RHESSI data analysis. We have…

Solar and Stellar Astrophysics · Physics 2015-06-11 Alexander A. Altyntsev , Gregory D. Fleishman , Sergey V. Lesovoi , Natalia S. Meshalkina

Continuum emission from a solar flare observed with the Extreme ultraviolet Imaging Spectrometer (EIS) on board the Hinode satellite is used to obtain the radiometric calibration of the instrument. The flare had a GOES class of M8, and…

Solar and Stellar Astrophysics · Physics 2026-05-07 Peter R. Young , Biswajit Mondal

We investigate the relationship between the main acceleration phase of coronal mass ejections (CMEs) and the particle acceleration in the associated flares as evidenced in RHESSI non-thermal X-rays for a set of 37 impulsive flare-CME…

Solar and Stellar Astrophysics · Physics 2012-05-14 S. Berkebile-Stoiser , A. M. Veronig , B. M. Bein , M. Temmer

Three homologous C-class flares and one last M-class flare were observed by both the Solar Dynamics Observatory (SDO) and the Hinode EUV Imaging Spectrometer (EIS) in the AR 11429 on March 9, 2012. All the recurrent flares occurred within a…

Solar and Stellar Astrophysics · Physics 2017-04-26 V. Polito , G. Del Zanna , G. Valori , E. Pariat , H. E. Mason , J. Dudik , M. Janvier

The aim of the present investigation is to study the spatio-temporal distribution of precursor flares during the 24-hour interval preceding M- and X-class major flares and the evolution of follower flares. Information on associated…

Solar and Stellar Astrophysics · Physics 2016-10-18 N. Gyenge , I. Ballai , T. Baranyi

This paper investigates the temporal evolution of temperature, emission measure, energy loss and velocity in a C-class solar flare from both an observational and theoretical perspective. The properties of the flare were derived by following…

Astrophysics · Physics 2009-11-13 Claire L. Raftery , Peter T. Gallagher , Ryan O. Milligan , James A. Klimchuk

This paper presents a detailed study of chromospheric evaporation using the EUV Imaging Spectrometer (EIS) onboard Hinode in conjunction with HXR observations from RHESSI. The advanced capabilities of EIS were used to measure Doppler shifts…

Solar and Stellar Astrophysics · Physics 2015-05-13 Ryan O. Milligan , Brian R. Dennis

We investigate the sequence of events leading to the solar X1 flare SOL2014-03-29T17:48. Because of the unprecedented joint observations of an X-flare with the ground-based Dunn Solar Telescope and the spacecraft IRIS, Hinode, RHESSI,…

Solar and Stellar Astrophysics · Physics 2015-06-11 Lucia Kleint , Marina Battaglia , Kevin Reardon , Alberto Sainz Dalda , Peter R. Young , Säm Krucker

Magnetic reconnection is the key mechanism for energy release in solar eruptions, where the high-temperature emission is the primary diagnostic for investigating the plasma properties during the reconnection process. Non-thermal broadening…

Solar and Stellar Astrophysics · Physics 2022-11-15 Chengcai Shen , Vanessa Polito , Katharine K. Reeves , Bin Chen , Sijie Yu , Xiaoyan Xie

We investigate the relationship between the blue shifts of a hot emission line and the nonthermal emissions in microwave and hard X-ray (HXR) wavelengths during the precursor of a solar flare on 2014 October 27. The flare precursor is…

Solar and Stellar Astrophysics · Physics 2018-02-21 Dong Li , Ying Li , Wei Su , Yu Huang , Zongjun Ning