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We investigate the cause of the suppressed Balmer series and the origin of the white-light continuum emission in the X1.0 class solar flare on 2014 June 11. We use radiative hydrodynamic simulations to model the response of the flaring…

Solar and Stellar Astrophysics · Physics 2018-08-08 Ondřej Procházka , Aaron Reid , Ryan O. Milligan , Paulo J. A. Simões , Joel C. Allred , Mihalis Mathioudakis

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

Increase in the Balmer continuum radiation during solar flares was predicted by various authors but never firmly confirmed observationally using ground-based slit spectrographs. Here we describe a new post-focal instrument - Image Selector…

Solar and Stellar Astrophysics · Physics 2016-02-02 P. Kotrč , O. Procházka , P. Heinzel

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

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

Solar white-light flares are characterized by an enhancement in the optical continuum, which are usually large flares (say X- and M-class flares). Here we report a small C2.3 white-light flare (SOL2022-12-20T04:10) observed by the…

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

The Hydrogen Balmer series is a basic radiative loss channel from the flaring solar chromosphere. We report here on the analysis of an extremely rare set of simultaneous observations of a solar flare in the H${\alpha}$ and H${\beta}$ lines…

(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

We present a homogeneous survey of line and continuum emission from near-ultraviolet (NUV) to optical wavelengths during twenty M dwarf flares with simultaneous, high cadence photometry and spectra. These data were obtained to study the…

High-cadence, multiwavelength optical observations of a solar active region (NOAA 10969), obtained with the Swedish Solar Telescope, are presented. Difference imaging of white light continuum data reveals a white light brightening, 2 min in…

Astrophysics · Physics 2009-11-13 D. B. Jess , M. Mathioudakis , P. J. Crockett , F. P. Keenan

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

Several redback and black widow millisecond pulsar binaries have episodes of flaring in X-rays and optical. We initially detected such behavior from the Fermi selected redback candidate 1FGL J0523.5$-$2529 during optical time-series…

High Energy Astrophysical Phenomena · Physics 2022-08-31 Jules P. Halpern , Karen I. Perez , Slavko Bogdanov

We present an extensive analysis of the multi-wavelength data of the low-synchrotron-peaked BL Lac object CGRaBS J0211+1051, which has been gathered over more than ten years with many observatories. Two major gamma-ray flares have been…

High Energy Astrophysical Phenomena · Physics 2025-11-14 Sunil Chandra , Pankaj Kushwaha , Pranjupriya Goswami , Michael Zacharias

The GOES X1 flare SOL2014-10-25T17:08:00 was a three-ribbon solar flare observed with IRIS in the near and far ultraviolet. One of the flare ribbons crossed a sunspot umbra, producing a dramatic, $\sim1000$% increase in the near-ultraviolet…

We present NUV flare spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph during two moderate-amplitude U-band flares on the dM4e star GJ 1243. These spectra are some of the first accurately flux-calibrated, NUV flare spectra…

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

Identifying the physical mechanisms of continuum emission in solar flares is important to improve our understanding of the transport of energy in the chromosphere. This study aims to quantify the occurrence statistics and spatial and…

Solar and Stellar Astrophysics · Physics 2026-04-14 Pranjali Sharma , Lucia Kleint , Jonas Zbinden

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

On April 17, 2024, the third successful Hi-C sounding rocket flight, Hi-C Flare, recorded coronal images in Fe XXI 129 A emission from 11 MK plasma during the post-maximum phase of an M1.6-class solar flare, achieving unprecedented spatial…

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