A Statistical Correlation of Sunquakes Based on Their Seismic and White-Light Emission

Buitrago-Casas, J. C.; Oliveros, J. C. Martinez; Lindsey, C.; Calvo-Mozo, B.; Krucker, S.; Glesener, Lindsay; Zharkov, S.

doi:10.1007/s11207-015-0786-9

Cited by 26 publications

(18 citation statements)

References 34 publications

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“…The sunquake origin is normally indicated by a compact bright (source) kernel peaking during the flare verified by statistical tests (Matthews et al 2011). TD diagrams and acoustic holography have been shown to be complementary (Zharkov et al 2011b(Zharkov et al , 2013aBuitrago-Casas et al 2015).…”

Section: Introductionmentioning

confidence: 90%

“…Some authors have suggested radiative back-warming as a source of pressure transients that can produce acoustic waves (Donea et al 2006;Donea 2011). However, observations show that not all sunquakes are associated with WL emission, with some found in the locations with little or no HXR and whitelight emission (Matthews et al 2011;Buitrago-Casas et al 2015;Zharkov et al 2011a). Based on the complex magnetic picture of flaring events, another driving mechanism is proposed to be related to the Lorentz force.…”

Section: Introductionmentioning

confidence: 99%

“…This red-shifted Hα emission often leads to a disappearance of Hα emission in the line core and reappearance again 10−20 s later (Druett & Zharkova 2018). In addition, precipitation of energetic electrons in solar flares leads to strong nonthermal plasma ionisation and prolonged white-light (WL) emission (Buitrago-Casas et al 2015;Zharkova 2008;Kuhar et al 2016;Kawate et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Lost and found sunquake in the 6 September 2011 flare caused by beam electrons

MacRae

Zharkov

Zharkova

et al. 2018

A&A

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The active region NOAA 11283 produced two X-class flares on 6 and 7 September 2011 that have been well studied by many authors. The X2.1 class flare occurred on September 6, 2011 and was associated with the first of two homologous white light flares produced by this region, but no sunquake was found with it despite the one being detected in the second flare of 7 September 2011. In this paper we present the first observation of a sunquake for the 6 September 2011 flare detected via statistical significance analysis of egression power and verified via directional holography and time–distance diagram. The surface wavefront exhibits directional preference in the north-west direction We interpret this sunquake and the associated flare emission with a combination of a radiative hydrodynamic model of a flaring atmosphere heated by electron beam and a hydrodynamic model of acoustic wave generation in the solar interior generated by a supersonic shock. The hydrodynamic model of the flaring atmosphere produces a hydrodynamic shock travelling with supersonic velocities toward the photosphere and beneath. For the first time we derive velocities (up to 140 km s−1) and onset time (about 50 s after flare onset) of the shock deposition at given depths of the interior. The shock parameters are confirmed by the radiative signatures in hard X-rays and white light emission observed from this flare. The shock propagation in the interior beneath the flare is found to generate acoustic waves elongated in the direction of shock propagation, that results in an anisotropic wavefront seen on the solar surface. Matching the detected seismic signatures on the solar surface with the acoustic wave front model derived for the simulated shock velocities, we infer that the shock has to be deposited under an angle of about 30° to the local solar vertical. Hence, the improved seismic detection technique combined with the double hydrodynamic model reported in this study opens new perspectives for observation and interpretation of seismic signatures in solar flares.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lost and found sunquake in the 6 September 2011 flare caused by beam electrons

MacRae

Zharkov

Zharkova

et al. 2018

A&A

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“…See Kosovichev (2011) for a comprehensive review of the basic principles of global and local helioseismology and see Kosovichev (2006) for a review of the properties of sunquakes. For examples of sunquakes see, e.g., Martínez-Oliveros et al (2008) and examples by Judge et al (2014), Matthews et al (2015), and Buitrago-Casas et al (2015). Kosovichev (2014b) reports that the excitation impact strongly correlates with the impulsive flare phase and is caused by the energy/momentum transported from the energyrelease site(s) but that the physical mechanism is currently uncertain.…”

Section: Future Directions and Key Unanswered Questionsmentioning

confidence: 99%

Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares

et al. 2018

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Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic pulsations (QPPs), to emphasise that they often contain apparent amplitude and period modulation. We review the current understanding of quasi-periodic pulsations in solar and stellar flares. In particular, we focus on the possible physical mechanisms, with an emphasis on the underlying physics that generates the resultant range of periodicities. These physical mechanisms include MHD oscillations, self-oscillatory mechanisms, oscillatory reconnection/reconnection reversal, wave-driven reconnection, two loop coalescence, MHD flow over-stability, the equivalent LCR-contour mechanism, and thermal-dynamical cycles. We also provide a histogram of all QPP events published in the literature at this time. The occurrence of QPPs puts additional constraints on the interpretation and understanding of the fundamental processes operating in flares, e.g. magnetic energy liberation and particle acceleration. Therefore, a full understanding of QPPs is essential in order to work towards an integrated model of solar and stellar flares.

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“…The other authors explored radiative back-warming as the other source of pressure transients producing acoustic waves in flares (Donea et al 2006;Donea 2011). However, the observations showed that nearly half of sunquake locations are associated with little or absent white light emission (Matthews et al 2011;Buitrago-Casas et al 2015;Zharkov et al 2011a). And the third mechanism of sunquakes generation can occur in the locations of Lorentz force transients, which, supposedly, produce a well-directed magnetic impulse of Poynting vector towards the photosphere and subsequent magneto-acoustic waves (Hudson et al 2008;Fisher et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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

Zharkova

Zharkov

Druett

et al. 2020

A&A

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In this paper we present the interpretation of the observations of the flare from 6 September 2017 reported in Paper I. These include gamma-ray (GR), hard X-ray (HXR), soft X-rays, Lyα line, extreme ultraviolet (EUV), Hα, and white light (WL) emission, which were recorded during the two flaring events 1 (FE1) and 2 (FE2) that occurred at 11:55:37 UT (FE1) and 12:06:40 UT (FE2). Paper I also reported the first detection of the sunquake with first and second bounces of seismic waves combined with four other sunquakes in different locations supported with the observations of HXR, GR, EUV, Hα, and WL emission with strongly varying spatial resolution and temporal coverage. In the current paper, we propose some likely scenarios for heating of flaring atmospheres in the footpoints with sunquakes which were supported with EUV and Hα emission. We used a range of parameters derived from the HXR, EUV, and Hα line observations to generate hydrodynamic models, which can account for the blueshifts derived from the EUV emission and the redshifts observed with the EUV Imaging Spectrometer in the He II line and by the CRisp Imaging Spectro-Polarimeter in the Swedish Solar Telescope in Hα line emission. The parameters of hydrodynamic shocks produced by different beams in flaring atmospheres were used as the initial conditions for another type of hydrodynamic models that were developed for acoustic wave propagation in the solar interior. These models simulate the sets of acoustic waves produced in the interior by the hydrodynamic shocks from atmospheres above deposited in different footpoints of magnetic loops. The Hα line profiles with large redshifts in three kernels (two in FE1 and one in FE2) were interpreted with the full non-local thermodynamic equilibrium radiative simulations in all optically thick transitions (Lyman lines and continuum Hα, Hβ, and Pα) applied for flaring atmospheres with fast downward motions while considering thermal and non-thermal excitation and ionisation of hydrogen atoms by energetic power-law electron beams. The observed Hα line profiles in three kernels were fit with the simulate blue wing emission of the Hα line profiles shifted significantly (by 4–6 Å) towards the line red wings, because of strong downward motions with velocities about 300 km s−1 by the shocks generated in flaring atmospheres by powerful beams. The flaring atmosphere associated with the largest sunquake (seismic source 2 in FE1) is found consistent with being induced by a strong hydrodynamic shock produced by a mixed beam deposited at an angle of −30° from the local vertical. We explain the occurrence of a second bounce in the largest sunquake by a stronger momentum delivered by the shock generated in the flaring atmosphere by a mixed beam and deeper depths of the interior where this shock was deposited. Indeed, the shock with mixed beam parameters is found deposited deeply into the interior beneath the flaring atmosphere under the angle to the local vertical that would allow the acoustic waves generated in the direction closer to the surface to conserve enough energy for the second bounces from the interior layers and from the photosphere. The wave characteristics of seismic sources 1 and 3 (in FE1) were consistent with those produced by the shocks generated by similar mixed beams deposited at the angles −(0 − 10)° (seismic source 1) and +30° (seismic source 3) to the local vertical. The differences of seismic signatures produced in the flares of 6 September 2011 and 2017 are also discussed.

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A Statistical Correlation of Sunquakes Based on Their Seismic and White-Light Emission

Cited by 26 publications

References 34 publications

Lost and found sunquake in the 6 September 2011 flare caused by beam electrons

Lost and found sunquake in the 6 September 2011 flare caused by beam electrons

Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares

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

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