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Related papers: Reproducing Type II White-Light Solar Flare Observ…

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Type II WLFs have weak Balmer line emission and no Balmer jump. We carried out a set of radiative hydrodynamic simulations to understand how the hydrogen radiative losses vary with the electron beam parameters and more specifically with the…

Solar and Stellar Astrophysics · Physics 2019-09-11 Ondřej Procházka , Aaron Reid , Mihalis Mathioudakis

We present unique NUV observations of a well-observed X-class flare from NOAA 12087 obtained at Ond\v{r}ejov Observatory. The flare shows a strong white-light continuum but no detectable emission in the higher Balmer and Lyman lines. RHESSI…

Solar and Stellar Astrophysics · Physics 2017-03-08 Ondřej Procházka , Ryan O. Milligan , Joel C. Allred , Adam F. Kowalski , Pavel Kotrč , Mihalis Mathioudakis

We analyze optical spectra of a two-ribbon, long duration C1.1 flare that occurred on 18 Aug 2011 within AR 11271 (SOL2011-08-18T15:15). The impulsive phase of the flare was observed with a comprehensive set of space-borne and ground-based…

Solar and Stellar Astrophysics · Physics 2015-06-23 Adam F. Kowalski , Gianna Cauzzi , Lyndsay Fletcher

Much of a solar flare's energy is thought to be released in the continuum. The optical continuum (white light) is of special interest due to the ability to observe it from the ground. We aim to investigate the prevalence of white-light (WL)…

Solar and Stellar Astrophysics · Physics 2026-01-21 Sascha Ornig , Mats Carlsson

The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic simulations in 1D have shown that high…

Solar and Stellar Astrophysics · Physics 2018-01-10 Adam F. Kowalski , Joel C. Allred

The heating mechanisms of solar white-light flares remain unclear. We present an X1.0 white-light flare on 2022 October 2 (SOL2022-10-02T20:25) observed by the Chinese \ha\ Solar Explorer (CHASE) that provides two-dimensional spectra in the…

Solar and Stellar Astrophysics · Physics 2023-07-25 De-Chao Song , Jun Tian , Y. Li , M. D. Ding , Yang Su , Sijie Yu , Jie Hong , Ye Qiu , Shihao Rao , Xiaofeng Liu , Qiao Li , Xingyao Chen , Chuan Li , Cheng Fang

The white-light continuum emissions in solar flares (i.e., white-light flares) are usually observed on the solar disk but, in a few cases, off the limb. Here we present on-disk as well as off-limb continuum emissions at 3600 {\AA} (in the…

Solar and Stellar Astrophysics · Physics 2024-02-13 Ying Li , Zhichen Jing , De-Chao Song , Qiao Li , Jun Tian , Xiaofeng Liu , Ya Wang , M. D. Ding , Andrea Francesco Battaglia , Li Feng , Hui Li , Weiqun Gan

Aims. We investigate the effect of the electric return currents in solar flares on the profiles of hydrogen Balmer lines. We consider the monoenergetic approximation for the primary beam and runaway model of the neutralizing return current.…

Astrophysics · Physics 2009-11-13 Jiri Stepan , Jana Kasparova , Marian Karlicky , Petr Heinzel

We present a novel observation of the white-light flare (WLF) continuum, which was significantly enhanced during the X1 flare on March 29, 2014 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its NUV…

Solar and Stellar Astrophysics · Physics 2015-06-22 Petr Heinzel , Lucia Kleint

While solar flares are primarily associated with enhanced ultraviolet and X-ray emission, a subset of flares exhibit significant continuum brightening in visible light and are classified as white-light flares (WLFs). Despite extensive…

Solar and Stellar Astrophysics · Physics 2026-01-01 Samuel Granovsky , Alexander G. Kosovichev , Irina N. Kitiashvili , Alan A. Wray

Low-energy protons entering the field of view of the XMM-Newton telescope scatter with the X-ray mirror surface and might reach the X-ray detectors on the focal plane. They manifest in the form of a sudden increase in the rates, usually…

High Energy Astrophysical Phenomena · Physics 2025-01-31 T. Mineo , V. Fioretti , S. Lotti , S. Molendi , G. Lanzuisi , M. Cappi , M. Dadina , S. Ettori , F. Gastaldello , R. Amato

Optical and near-UV continuum emissions in flares contribute substantially to flare energy budget. Two mechanisms play an important role for continuum emission in flares: hydrogen recombination after sudden ionization at chromospheric…

Solar and Stellar Astrophysics · Physics 2021-10-13 Reetika Joshi , Brigitte Schmieder , Petr Heinzel , James Tomin , Ramesh Chandra , Nicole Vilmer

White light flares (WLFs) are observational rarities, making them understudied events. However, optical emission is a significant contribution to flare energy budgets and the emission mechanisms responsible could have important implications…

Solar and Stellar Astrophysics · Physics 2015-06-18 Graham Stewart Kerr , Lyndsay Fletcher

The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms…

Solar and Stellar Astrophysics · Physics 2017-02-17 Adam F. Kowalski , Joel C. Allred , Adrian N. Daw , Gianna Cauzzi , Mats Carlsson

(abridged) The heating mechanism at high densities during M dwarf flares is poorly understood. Spectra of M dwarf flares in the optical and near-ultraviolet wavelength regimes have revealed three continuum components during the impulsive…

Solar and Stellar Astrophysics · Physics 2015-06-23 Adam F. Kowalski , Suzanne L. Hawley , Mats Carlsson , Joel C. Allred , Han Uitenbroek , Rachel A. Osten , Gordon Holman

Red-shifted components of chromospheric emission lines in the hard X-ray impulsive phase of solar flares have recently been studied through their 30 s evolution with the high resolution of IRIS. Radiative-hydrodynamic flare models show that…

Spectroscopic observations of solar flares provide critical diagnostics of the physical conditions in the flaring atmosphere. Some key features in observed spectra have not yet been accounted for in existing flare models. Here we report a…

Solar and Stellar Astrophysics · Physics 2016-08-16 Fatima Rubio da Costa , Lucia Kleint , Vahé Petrosian , Wei Liu , Joel C. Allred

We report observations of white-light ejecta in the low corona, for two X-class flares on the 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources…

White-light emissions were observed from an X1.7 class solar flare on 27 January 2012, using three continuum bands (red, green, and blue) of the Solar Optical Telescope (SOT) onboard the Hinode satellite. This event occurred near the solar…

Solar and Stellar Astrophysics · Physics 2015-06-17 Kyoko Watanabe , Toshifumi Shimizu , Satoshi Masuda , Kiyoshi Ichimoto , Masanori Ohno

Enhanced continuum brightness is observed in many flares (''white light flares''), yet it is still unclear which processes contribute to the emission. To understand the transport of energy needed to account for this emission, we must first…

Solar and Stellar Astrophysics · Physics 2016-01-27 Lucia Kleint , Petr Heinzel , Phil Judge , Säm Krucker
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