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RHESSI measurements relevant to the fundamental processes of energy release and particle acceleration in flares are summarized. RHESSI's precise measurements of hard X-ray continuum spectra enable model-independent deconvolution to obtain…

Solar and Stellar Astrophysics · Physics 2011-10-11 R. P. Lin

The evolution of an X2.7 solar flare, that occurred in a complex $\beta\gamma\delta$ magnetic configuration region on 2003 November 3 is discussed utilizing a multi-wavelength data set. The very first signature of pre-flare coronal activity…

Astrophysics · Physics 2009-11-13 Bhuwan Joshi , P. K. Manoharan , Astrid M. Veronig , P. Pant , Kavita Pandey

We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, red-shifted…

Solar and Stellar Astrophysics · Physics 2023-06-29 Dong Li , Chuan Li , Ye Qiu , Shihao Rao , Alexander Warmuth , Frederic Schuller , Haisheng Zhao , Fanpeng Shi , Jun Xu , Zongjun Ning

We assess the on-orbit performance of the flare event trigger for the Hinode EUV Imaging Spectrometer. Our goal is to understand the time-delay between the occurrence of a flare, as defined by a prompt rise in soft X-ray emission, and the…

Solar and Stellar Astrophysics · Physics 2023-03-24 David H. Brooks , Jeffrey W. Reep , Ignacio Ugarte-Urra , Harry P. Warren

(Abridged) We investigate the EUV and X-ray flare rate distribution in radiated energy of the late-type active star AD Leo using long EUVE and BeppoSAX observations. We compare the observed light curves with light curves synthesized from…

Astrophysics · Physics 2009-11-07 Manuel Guedel , Marc Audard , Vinay L. Kashyap , Jeremy J. Drake , Edward F. Guinan

With observations from the Interface Region Imaging Spectrograph (IRIS), we track the complete evolution of $\sim$11 MK evaporation flows in an M1.1 flare on 2014 September 6 and an X1.6 flare on 2014 September 10. These hot flows, as…

Solar and Stellar Astrophysics · Physics 2015-10-07 Hui Tian , Peter R. Young , Katharine K. Reeves , Bin Chen , Wei Liu , Sean McKillop

The acceleration mechanism of EUV/X-ray jets is still unclear. For the most part, there are two candidates for the mechanism. One is magnetic reconnection, and the other is chromospheric evaporation. We observed a relatively compact X-ray…

Solar and Stellar Astrophysics · Physics 2019-06-19 Toshiki Kawai , Natsuo Kanda , Shinsuke Imada

We analyze spectropolarimetric data taken with the Hinode spacecraft in quiet solar regions at the disk center. Distorted redshifted Stokes $V$ profiles are found showing a characteristic evolution that always follows the same sequence of…

Solar and Stellar Astrophysics · Physics 2014-07-02 Carlos Quintero Noda , Basilio Ruiz Cobo , David Orozco Suárez

During solar flares, a considerable portion of the flare atmosphere becomes heated; however, the energy deposition process is still unclear, especially in the lower solar atmosphere. Here, we present spectroscopic and imaging observations…

Solar and Stellar Astrophysics · Physics 2026-03-24 Girjesh Gupta , Ananya Rawat , Helen Mason , Robertus Erdélyi

The presence of flare related acoustic emission (sunquakes) in some flares represents a severe challenge to our current understanding of flare energy transport processes. We present a comparison of new spectral observations from Hinode's…

Solar and Stellar Astrophysics · Physics 2015-10-14 Sarah A. Matthews , Louise K. Harra , Sergei Zharkov , Lucie M. Green

HD 189733 is an exoplanetary system consisting of a transiting hot Jupiter and an active K2V-type main sequence star. We aim to use VLT/UVES high resolution echelle spectra to study a stellar flare. We have performed simultaneous analyses…

Solar and Stellar Astrophysics · Physics 2017-11-15 T. Klocova , S. Czesla , S. Khalafinejad , U. Wolter , J. H. M. M. Schmitt

We investigate gamma-ray emission in the impulsive phase of solar flares and the detectability of non-thermal signatures from protostellar flares. Energetic solar flares emit high-energy gamma rays of GeV energies, but their production…

High Energy Astrophysical Phenomena · Physics 2023-03-08 Shigeo S. Kimura , Shinsuke Takasao , Kengo Tomida

This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form…

In this study we present the analysis of six solar flare events that occurred in 2022, using new data from the third-generation Miniature X-Ray Solar Spectrometer (MinXSS), also known as the Dual-zone Aperture X-ray Solar Spectrometer…

Solar and Stellar Astrophysics · Physics 2024-03-12 Anant Telikicherla , Thomas N. Woods , Bennet D. Schwab

We analyze and model a C5.7 two-ribbon solar flare observed by SDO, Hinode and GOES on 2011 December 26. The flare is made of many loops formed and heated successively over one and half hours, and their footpoints are brightened in the UV…

Solar and Stellar Astrophysics · Physics 2018-04-04 Chunming Zhu , Jiong Qiu , Dana W. Longcope

The energy released during solar flares is believed to be stored in non-potential magnetic fields associated with electric currents flowing in the corona. While no measurements of coronal electric currents are presently available, maps of…

Solar and Stellar Astrophysics · Physics 2015-08-19 Sophie Musset , Nicole Vilmer , Véronique Bommier

We studied an X1.6 solar flare produced by NOAA AR 12602 on 2014 October 22. The entirety of this event was covered by RHESSI, IRIS, and Hinode/EIS, allowing analysis of the chromospheric response to a nonthermal electron driver. We derived…

Solar and Stellar Astrophysics · Physics 2022-09-07 Sean G. Sellers , Ryan O. Milligan , R. T. James McAteer

Nanoflares, short and intense heat pulses within spatially unresolved magnetic strands, are now considered a leading candidate to solve the coronal heating problem. However, the frequent occurrence of nanoflares requires that flare-hot…

Solar and Stellar Astrophysics · Physics 2011-02-11 Fabio Reale , Paola Testa , James A. Klimchuk , Susanna Parenti

Solar flares are currently understood as the explosive release of energy stored in the form of stressed magnetic fields. In many cases, the released energy seems to take the form of large numbers of electrons accelerated to high energies or…

Solar and Stellar Astrophysics · Physics 2010-05-18 George H. Fisher

An X1.6 flare occurred in AR 12192 on 2014 October 22 at 14:02 UT and was observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel which produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak.…

Solar and Stellar Astrophysics · Physics 2017-02-22 Kyoung-Sun Lee , Shinsuke Imada , Kyoko Watanabe , Yumi Bamba , David H. Brooks