Quasi-periodic Pulsations in the Most Powerful Solar Flare of Cycle 24

Kolotkov, Dmitrii Y.; Pugh, Chloe E.; Broomhall, Anne-Marie; Nakariakov, V. M.

doi:10.3847/2041-8213/aabde9

Cited by 42 publications

(41 citation statements)

References 44 publications

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“…Usually, the damping time is determined from the best-fitting exponential decay function. But, it has been shown that in some cases a Gaussian decay is more appropriate [12,32]. Physical mechanisms responsible for the Gaussian damping of slow magnetoacoustic waves in the corona have not been identified yet, but are known in the case of coronal fast magnetoacoustic waves of the kink symmetry [44].…”

Section: Decaying Harmonic Qppmentioning

confidence: 99%

“…However the flare trend does have a significant impact on the shape of flare power spectra (e.g., [32]), and as such can make QPP signals much more difficult to detect [35]. Therefore there is a huge incentive to detrend flare light curves using an analytical model, in a way that does not risk introducing artificial signal that may be misinterpreted as QPP.…”

Section: The Trendmentioning

confidence: 99%

“…Operating locally and hence adaptively, it iteratively sifts these time scales from the signal thus forming a set of intrinsic mode functions (IMFs or 'intrinsic modes') each of them potentially representing a certain non-stationary and anharmonic oscillatory process in the original signal. EMD has been used for the detection of non-stationary multi-modal QPP in solar (e.g., [28,31,32]) and stellar flares (e.g., [31,33]). However, the full scale application of this technique requires deeper understanding of its properties and shortcomings.…”

Section: Qpp Detection and Analysismentioning

confidence: 99%

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Non-stationary quasi-periodic pulsations in solar and stellar flares

Nakariakov

Kolotkov

Kupriyanova

et al. 2018

Plasma Phys. Control. Fusion

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Often the enhanced electromagnetic radiation generated in solar and stellar flares shows a pronounced (quasi)-oscillatory pattern-quasi-periodic pulsations (QPP), with characteristic periods ranging from a fraction of a second to several tens of minutes. We review recent advances in the empirical study of QPP in solar and stellar flares, addressing the intrinsic nonstationarity of the signal, i.e. the variation of its amplitude, period or phase with time. This nonstationarity could form a basis for a classification of QPP, necessary for revealing specific physical mechanisms responsible for their appearance. We could identify two possible classes of QPP, decaying harmonic oscillations, and trains of symmetric triangular pulsations. Apparent similarities between QPP and irregular geomagnetic pulsations Pi offer a promising avenue for the knowledge transfer in both analytical techniques and theory. Attention is also paid to the effect of the flare trend on the detection and analysis of QPP.

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Section: Decaying Harmonic Qppmentioning

confidence: 99%

Section: The Trendmentioning

confidence: 99%

Section: Qpp Detection and Analysismentioning

confidence: 99%

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Non-stationary quasi-periodic pulsations in solar and stellar flares

Nakariakov

Kolotkov

Kupriyanova

et al. 2018

Plasma Phys. Control. Fusion

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“…There is increasing evidence to support the theory that QPPs are a common feature of both solar and stellar flares (Kupriyanova et al 2010;Simões et al 2013;Inglis et al 2016;Pugh et al 2016Pugh et al , 2017. For example, they were recently observed in the largest solar flare of cycle 24 to date (Kolotkov et al 2018). This X9.3 class flare was estimated to have an energy of around 10 32 erg, and therefore bridges the energy gap observed between solar and stellar flares.…”

Section: Introductionmentioning

confidence: 99%

Multi-waveband detection of quasi-periodic pulsations in a stellar flare on EK Draconis observed by XMM-Newton

Broomhall

Thomas

Pugh

et al. 2019

A&A

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Context. Quasi-periodic pulsations (QPPs) are time variations in the energy emission during a flare that are observed on both the Sun and other stars and thus have the potential to link the physics of solar and stellar flares. Aims. To characterise the QPPs detected in an X-ray flare on the solar analogue, EK Draconis, which was observed by XMM-Newton. Methods. We use wavelet and autocorrelation techniques to identify the QPPs in a detrended version of the flare. We also fit a model to the flare based on an exponential decay combined with a decaying sinusoid. The flare is examined in multiple energy bands. Results. A statistically significant QPP is observed in the X-ray energy band of 0.2-12.0 keV with a periodicity of 76 ± 2 min. When this energy band is split, a statistically significant QPP is observed in the low-energy band (0.2-1.0 keV) with a periodicity of 73±2 min and in the high-energy band (1.0-12.0 keV) with a periodicity of 82 ± 2 min. When fitting a model to the time series the phases of the signals are also found to be significantly different in the two energy bands (with a difference of 1.8 ± 0.2 rad) and the high-energy band is found to lead the low-energy band. Furthermore, the first peak in the cross-correlation between the detrended residuals of the lowand high-energy bands is offset from zero by more than 3σ (4.1 ± 1.3 min). Both energy bands produce statistically significant regions in the wavelet spectrum, whose periods are consistent with those listed above. However, the peaks are broad in both the wavelet and global power spectra, with the wavelet showing evidence for a drift in period with time, and the difference in period obtained is not significant. The offset in the first peak in the cross-correlation of the detrended residuals of two non-congruent energy bands (0.5 − 1.0 keV and 4.5 − 12.0 keV) is found to be even larger (10 ± 2 min). However, the signal-to-noise in the higher of these two energy-bands, covering the range 4.5 − 12.0 keV, is low. Conclusions. The presence of QPPs similar to those observed on the Sun, and other stars, suggests that the physics of flares on this young solar analogue is similar to the physics of solar flares. It is possible that the differences in the QPPs detected in the two energy bands are seen because each band observes a different plasma structure. However, the phase difference, which differs more significantly between the two energy bands than the period, could also be explained in terms of the Neupert effect. This suggests that QPPs are caused by the modulation of the propagation speeds of charged particles.

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“…Moreover, SOL2017‐09‐06 produced two coronal mass ejections, one near the peak time and the next 1 hr later (Goryaev et al, ). It was pointed out that the total emitted energy by the flare is about 10 (25) J, that is, in the lower limit of a super flare (Kolotkov et al, ). In this paper we report the observation of SOL2017‐09‐06 at the wavelengths of 10 μm (mid‐IR) and 0.7 and 1.4 mm (submillimeter).…”

Section: Introductionmentioning

confidence: 99%

The 6 September 2017 X9 Super Flare Observed From Submillimeter to Mid‐IR

et al. 2018

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Active Region 12673 is the most productive active region of solar cycle 24: in a few days of early September 2017, four X‐class and 27 M‐class flares occurred. SOL2017‐09‐06T12:00, an X9.3 flare also produced a two‐ribbon white light emission across the sunspot detected by Solar Dynamics Orbiter/Helioseismic and Magnetic Imager. The flare was observed at 212 and 405 GHz with the arcminute‐sized beams of the Solar Submillimeter Telescope focal array while making a solar map and at 10 μm, with a 17 arcsec diffraction‐limited infrared camera. Images at 10 μm revealed that the sunspot gradually increased in brightness while the event proceeded, reaching a temperature similar to quiet Sun values. From the images we derive a lower bound limit of 180‐K flare peak excess brightness temperature or 7,000 sfu if we consider a similar size as the white light source. The rising phase of mid‐IR and white light is similar, although the latter decays faster, and the maximum of the mid‐IR and white light emission is ∼200 s delayed from the 15.4‐GHz peak occurrence. The submillimeter spectrum has a different origin than that of microwaves from 1 to 15 GHz, although it is not possible to draw a definitive conclusion about its emitting mechanism.

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Quasi-periodic Pulsations in the Most Powerful Solar Flare of Cycle 24

Cited by 42 publications

References 44 publications

Non-stationary quasi-periodic pulsations in solar and stellar flares

Non-stationary quasi-periodic pulsations in solar and stellar flares

Multi-waveband detection of quasi-periodic pulsations in a stellar flare on EK Draconis observed by XMM-Newton

The 6 September 2017 X9 Super Flare Observed From Submillimeter to Mid‐IR

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