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It is argued that not only the blue (at the brightness maximum) but also the red (in the slow decay phase) components of the optical continuum of powerful flares on dMe stars are formed near the photosphere. The possible appearance of HeI…

Solar and Stellar Astrophysics · Physics 2020-10-20 E. S. Morchenko

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

M dwarfs produce explosive flare emission in the near-UV and optical continuum, and the mechanism responsible for this phenomenon is not well-understood. We present a near-UV/optical flare spectrum from the rise phase of a secondary flare,…

Solar and Stellar Astrophysics · Physics 2015-03-17 Adam F. Kowalski , Suzanne L. Hawley , Jon A. Holtzman , John P. Wisniewski , Eric J. Hilton

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

We present a long (150 ks elapsed time) ASCA X-ray observation of the dM3.5e star EV Lac, during which an exceptionally intense flaring event (lasting approximately 12 ks) was observed: at the flare's peak, the X-ray count rate in the ASCA…

Astrophysics · Physics 2007-05-23 F. Favata , F. Reale , G. Micela , S. Sciortino , A. Maggio , H. Matsumoto

We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17T17:50 (C7.0), using Quantum Well Infrared Photodetector (QWIP) cameras at an auxiliary of the McMath-Pierce telescope. The flare…

Solar and Stellar Astrophysics · Physics 2016-03-23 M Penn , S Krucker , H Hudson , M Jhabvala , D Jennings , A Lunsford , P Kaufmann

We study the spectral and temporal behavior of X-ray flares from the active M-dwarf EV Lac in 200 ks of exposure with the Chandra/HETGS. We derive flare parameters by fitting an empirical function which characterizes the amplitude, shape,…

High Energy Astrophysical Phenomena · Physics 2015-05-19 David P. Huenemoerder , Norbert S. Schulz , Paola Testa , Jeremy J. Drake , Rachel A. Osten , Fabio Reale

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 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

We investigate the relationship between the continuum enhancement and the hard X-ray (HXR) emission of a white-light flare on 2002 September 29. By reconstructing the RHESSI HXR images in the impulsive phase, we find two bright conjugate…

Astrophysics · Physics 2014-10-13 Q. R. Chen , M. D. Ding

White-light flares are the flares with emissions visible in the optical continuum. They are thought to be rare and pose the most stringent requirements in energy transport and heating in the lower atmosphere. Here we present a nearly…

Solar and Stellar Astrophysics · Physics 2017-12-21 Q. Hao , K. Yang , X. Cheng , Y. Guo , C. Fang , M. D. Ding , P. F. Chen , Z. Li

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

We present the results of a campaign to observe flares on the M dwarf flare star EV Lacertae over the course of two days in 2001 September, utilizing a combination of radio continuum, optical photometric and spectroscopic, ultraviolet…

Astrophysics · Physics 2009-11-10 R. A. Osten , S. L. Hawley , J. C. Allred , C. M. Johns-Krull , C. Roark

The young active flare star AU~Mic is the planet host star with the highest flare rate from TESS data. Therefore, it represents an ideal target for dedicated ground-based monitoring campaigns with the aim to characterize its numerous flares…

We report the white light flare rates for 10 ultracool dwarfs (UCDs) using \textit{Kepler K2} short cadence data. Among our sample stars, two have spectral type M6, three are M7, three are M8 and two are L0. Most of our targets are old low…

Solar and Stellar Astrophysics · Physics 2018-06-06 Rishi R. Paudel , John E. Gizis , D. J. Mullan , Sarah J. Schmidt , Adam J. Burgasser , Peter K. G. Williams , Edo Berger

We present observations of the 2002 September 30 white-light flare, in which the optical continuum emission near the Halpha line is enhanced by ~10%. The continuum emission exhibits a close temporal and spatial coincidence with the hard…

Astrophysics · Physics 2009-11-13 Q. R. Chen , M. D. Ding

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

Solar flares radiates energy at all wavelengths, but the spectral distribution of this energy is still poorly known. White-light continuum emission is sometimes observed and the flares are then termed "white-light flares" (WLF). In this…

Solar and Stellar Astrophysics · Physics 2015-03-19 M. Kretzschmar

M-dwarf flares observed by the \textit{Transiting Exoplanet Survey Satellite} (\textit{TESS}) sometimes exhibit a "peak-bump" light-curve morphology, characterized by a secondary, gradual peak well after the main, impulsive peak. A similar…

Solar and Stellar Astrophysics · Physics 2023-10-31 Kai E. Yang , Xudong Sun , Graham S. Kerr , Hugh S. Hudson