Reproducing Type II White-light Solar Flare Observations with Electron and Proton Beam Simulations

Prochazka, Ondrej; Reid, Aaron; Milligan, Ryan O.; Simões, Paulo J. A.; Allred, Joel C.; Mathioudakis, M.

doi:10.3847/1538-4357/aaca37

Cited by 27 publications

(24 citation statements)

References 46 publications

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“…The spectral index δ was equal to 3 for all models. The beams were applied continuously and the outputs were analysed at t = 20 s. This value is consistent with the X-ray analysis of the best observed type II WLF to date (Procházka et al 2018). The initial atmosphere used in this work has the transition region placed at a height of 1200 km above the photospheric floor and has a coronal temperature of 3 MK at 10 Mm (QS.SL.HT loop described in Allred et al 2015).…”

Section: Flare Modellingsupporting

confidence: 66%

“…The Spectral Investigation of the Coronal Environment (SPICE, Fludra et al 2013) instrument on board the Solar Orbiter, that is due to be launched in 2020, will record spectra in the wavelength ranges 70.4 − 79.0 nm and 97.3 − 104.9 nm. These spectral ranges cover the higher Lyman lines and continuum as well as lines from several ionized species formed at temperatures from 10 thousand to 10 million K. Particle beams with a E C greater than 100 keV were directly observed only once by Warmuth et al (2009), but they were also found to be consistent with the spectral features of type II WLF (Procházka et al 2018). Their work confirms that these beams produce a weaker excess Balmer emission than the low E C particle beams consistent with the definition of the type II WLFs.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 82%

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Hydrogen Emission in Type II White-light Solar Flares

Prochazka

Reid

Mathioudakis

2019

ApJ

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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 low energy cutoff. Our results have revealed that for low energy beams, the excess flare Lyman emission diminishes with increasing low energy cutoff as the energy deposited into the top chromosphere is low compared to the energy deposited into the deeper layers. Some Balmer excess emission is always present and is driven primarily by direct heating from the beam with a minor contribution from Lyman continuum backwarming. The absence of Lyman excess emission in electron beam models with high low energy cutoff is a prominent spectral signature of type II WLFs.

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Section: Flare Modellingsupporting

confidence: 66%

Section: Discussion and Concluding Remarksmentioning

confidence: 82%

Hydrogen Emission in Type II White-light Solar Flares

Prochazka

Reid

Mathioudakis

2019

ApJ

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“…We can then hypothesize that if the Balmer to X-ray relation extends to the integrated white-light part of the spectrum, we expect that the energy emitted in X-rays for more active stars will increase to more than 1%. However, Procházka et al (2018) for example, used sophisticated particle beam models to investigate the energy partition during the solar flare event of 2014 June 11 and specifically understand the suppressed Balmer line emission. Therein the authors showed that during the impulsive phase of the flare only the H α line was in emission, while higher Balmer lines remained in absorption.…”

Section: White-light Versus X-ray Energy Partitionmentioning

confidence: 99%

The Stellar CME–Flare Relation: What Do Historic Observations Reveal?

Moschou

Drake

Cohen

et al. 2019

ApJ

111

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Solar CMEs and flares have a statistically well defined relation, with more energetic X-ray flares corresponding to faster and more massive CMEs. How this relation extends to more magnetically active stars is a subject of open research. Here, we study the most probable stellar CME candidates associated with flares captured in the literature to date, all of which were observed on magnetically active stars. We use a simple CME model to derive masses and kinetic energies from observed quantities, and transform associated flare data to the GOES 1-8 Å band. Derived CME masses range from ∼ 10 15 to 10 22 g. Associated flare X-ray energies range from 10 31 to 10 37 erg. Stellar CME masses as a function of associated flare energy generally lie along or below the extrapolated mean for solar events. In contrast, CME kinetic energies lie below the analogous solar extrapolation by roughly two orders of magnitude, indicating approximate parity between flare X-ray and CME kinetic energies. These results suggest that the CMEs associated with very energetic flares on active stars are more limited in terms of the ejecta velocity than the ejecta mass, possibly because of the restraining influence of strong overlying magnetic fields and stellar wind drag. Lower CME kinetic energies and velocities present a more optimistic scenario for the effects of CME impacts on exoplanets in close proximity to active stellar hosts.

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“…), followed at later times by blueshifts as observed in stellar flares (Houdebine et al 1990;Houdebine & Doyle 1994). In addition, notable increases in white light (WL, or Paschen continuum) emission (Uchida & Hudson 1972;Kurokawa et al 1988;Matthews et al 2011;Procházka et al 2018), Balmer and near-UV continuum emission (Kleint et al 2016;Kotrč et al 2016;Druett & Zharkova 2018;Procházka et al 2018) are often observed during early phases of flares. The locations of WL or Balmer continuum emission are nearly co-spatial with the contours of HXR emission and have close depths of formation in flaring atmospheres (Druett & Zharkova 2018).…”

Section: Introductionmentioning

confidence: 99%

Sunquake with a second bounce, other sunquakes, and emission associated with the X9.3 flare of 6 September 2017

Zharkov

Matthews²,

Zharkova

et al. 2020

A&A

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Aims. The 6 September 2017 X9.3 solar flare produced very unique observations of magnetic field transients and a few seismic responses, or sunquakes, detected by the Helioseismic and Magnetic Imager (HMI) instrument aboard Solar Dynamic Observatory (SDO) spacecraft, including the strongest sunquake ever reported. This flare was one of a few flares occurring within a few days or hours in the same active region. Despite numerous reports of the fast variations of magnetic field, and seismic and white light emission, no attempts were made to interpret the flare features using multi-wavelength observations. In this study, we attempt to produce the summary of available observations of the most powerful flare of the 6 September 2017 obtained using instruments with different spatial resolutions (this paper) and to provide possible interpretation of the flaring events, which occurred in the locations of some seismic sources (a companion Paper II). Methods. We employed non-linear force-free field extrapolations followed by magnetohydrodynamic simulations in order to identify the presence of several magnetic flux ropes prior to the initiation of this X9.3 flare. Sunquakes were observed using the directional holography and time–distance diagram detection techniques. The high-resolution method to detect the Hα line kernels in the CRISP instrument at the diffraction level limit was also applied. Results. We explore the available γ-ray (GR), hard X-ray (HXR), Lyman-α, and extreme ultra-violet (EUV) emission for this flare comprising two flaring events observed by space- and ground-based instruments with different spatial resolutions. For each flaring event we detect a few seismic sources, or sunquakes, using Dopplergrams from the HMI/SDO instrument coinciding with the kernels of Hα line emission with strong redshifts and white light sources. The properties of sunquakes were explored simultaneously with the observations of HXR (with KONUS/WIND and the Reuven Ramaty High Energy Solar Spectroscopic Imager payload), EUV (with the Atmospheric Imaging Assembly (AIA/SDO and the EUV Imaging Spectrometer aboard Hinode payload), Hα line emission (with the CRisp Imaging Spectro-Polarimeter (CRISP) in the Swedish Solar Telescope), and white light emission (with HMI/SDO). The locations of sunquake and Hα kernels are associated with the footpoints of magnetic flux ropes formed immediately before the X9.3 flare onset. Conclusions. For the first time we present the detection of the largest sunquake ever recorded with the first and second bounces of acoustic waves generated in the solar interior, the ripples of which appear at a short distance of 5–8 Mm from the initial flare location. Four other sunquakes were also detected, one of which is likely to have occurred 10 min later in the same location as the largest sunquake. Possible parameters of flaring atmospheres in the locations with sunquakes are discussed using available temporal and spatial coverage of hard X-ray, GR, EUV, hydrogen Hα-line, and white light emission in preparation for their use in an interpretation to be given in Paper II.

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Reproducing Type II White-light Solar Flare Observations with Electron and Proton Beam Simulations

Cited by 27 publications

References 46 publications

Hydrogen Emission in Type II White-light Solar Flares

Hydrogen Emission in Type II White-light Solar Flares

The Stellar CME–Flare Relation: What Do Historic Observations Reveal?

Sunquake with a second bounce, other sunquakes, and emission associated with the X9.3 flare of 6 September 2017

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