<i>SOLAR DYNAMICS OBSERVATORY</i>/ATMOSPHERIC IMAGING ASSEMBLY OBSERVATIONS OF A REFLECTING LONGITUDINAL WAVE IN A CORONAL LOOP

Kumar, Pankaj; Innes, D. E.; Inhester, B.

doi:10.1088/2041-8205/779/1/l7

Cited by 55 publications

(71 citation statements)

References 36 publications

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“…In numerical experiments, Fang et al (2015) found that these flows result in periodic emission in the footpoints, and can be directly observed in the flare loop body (confirming the interpretation of the observations of Kumar, Innes, and Inhester, 2013;Kumar, Nakariakov, and Cho, 2015). Moreover, such a mechanism may be responsible for the standing slow waves observed in hot flare loops with SUMER (Wang, 2011;Yuan et al, 2015).…”

Section: Mhd Waves In Flaring Systemsupporting

confidence: 58%

Quasi-periodic Pulsations in Solar and Stellar Flares: An Overview of Recent Results (Invited Review)

2016

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Quasi-periodic pulsations (or QPPs) are periodic intensity variations in the flare emission, across all wavelength bands. In this paper, we review the observational and modelling achievements since the previous review on this topic by Nakariakov and Melnikov (2009). In recent years, it has become clear that QPPs are an inherent feature of solar flares, because almost all flares exhibit QPPs. Moreover, it is now firmly established that QPPs often show multiple periods. We also review possible mechanisms for generating QPPs. Up to now, it has not been possible to conclusively identify the triggering mechanism or cause of QPPs. The lack of this identification currently hampers possible seismological inferences of flare plasma parameters. QPPs in stellar flares have been detected for a long time, and the high quality data of the Kepler mission allows to study the QPP more systematically. However, it has not been conclusively shown whether the time scales of stellar QPPs are different or the same as those in solar flares.

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Section: Mhd Waves In Flaring Systemsupporting

confidence: 58%

Quasi-periodic Pulsations in Solar and Stellar Flares: An Overview of Recent Results (Invited Review)

2016

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“…In contrast, in the other case with the classical thermal conduction and viscosity coefficients, the scaling relation between the decay time and the period is linear, and a timescale of several reflections is required for the initial propagating disturbance to form the standing wave pattern. This latter loop model may explain the reflected propagating feature of a longitudinal wave event reported in Kumar et al (2013).…”

Section: Discussionmentioning

confidence: 76%

“…Like the SUMER oscillation events (e.g. Wang et al 2005), the initiation of the AIA longitudinal waves is also associated with small flares (GOES B or C-class) at the loop footpoint (Kumar et al 2013(Kumar et al , 2015Wang et al 2015;Nisticó et al 2017). Magnetic extrapolation and emission features suggest that the confined flares are produced by reconnections at a coronal null point in a fan-spine magnetic topology Kumar et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Determination of Transport Coefficients by Coronal Seismology of Flare-induced Slow-mode Waves: Numerical Parametric Study of a 1D Loop Model

Wang

Ofman

2019

ApJ

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Recent studies of a flaring loop oscillation event on 2013 December 28 observed by the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) have revealed the suppression of thermal conduction and significant enhancement of compressive viscosity in hot (∼10 MK) plasma. In this study we aim at developing a new coronal seismology method for determining the transport coefficients based on a parametric study of wave properties using a 1D nonlinear MHD loop model in combination with the linear theory. The simulations suggest a two-step scheme: we first determine the effective thermal conduction coefficient from the observed phase shift between temperature and density perturbations as this physical parameter is insensitive to the unknown viscosity; then from the loop model with the obtained thermal conduction coefficient, we determine the effective viscosity coefficient from the observed decay time using the parametric modeling. With this new seismology technique we are able to quantify the suppression of thermal conductivity by a factor of about 3 and the enhancement of viscosity coefficient by a factor of 10 in the studied flaring loop. Using the loop model with these refined transport coefficients, we study the excitation of slow magnetoacoustic waves by launching a flow pulse from one footpoint. The simulation can self-consistently produce the fundamental standing wave on a timescale in agreement with the observation.

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“…If one suggests the modulation by MHD waves, a plausible step is to correlate the timestamps in integrated light curves and periodic waves. A series of studies was done on modulation by standing and reflective slow mode waves (Wang et al 2003a,b;Wang 2011;Kumar et al 2013Kumar et al , 2015Yuan et al 2015;Fang et al 2015;Mandal et al 2016). Most previous studies focus on a good match of periodicity and phase difference.…”

Section: Introductionmentioning

confidence: 99%

A Compact Source for Quasi-periodic Pulsation in an M-class Solar Flare

Yuan

Feng

Dong

et al. 2019

ApJL

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Quasi-periodic pulsations (QPP) are usually found in the light curves of solar and stellar flares, they carry the features of time characteristics and plasma emission of the flaring core, and could be used to diagnose the coronas of the Sun and remote stars. In this study, we combined the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and the Nobeyama Radioheliograph (NoRH) to observe an M7.7 class flare occurred at active region 11520 on 19 July 2012. A QPP was detected both in the AIA 131Å bandpass and the NoRH 17 GHz channel, it had a period of about four minutes. In the spatial distribution of Fourier power, we found that this QPP originated from a compact source and that it overlapped with the X-ray source above the loop top. The plasma emission intensities in the AIA 131Å bandpass were highly correlated within this region. The source region is further segmented into stripes that oscillated with distinctive phases. Evidence in this event suggests that this QPP was likely to be generated by intermittent energy injection into the reconnection region.

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SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY OBSERVATIONS OF A REFLECTING LONGITUDINAL WAVE IN A CORONAL LOOP

Cited by 55 publications

References 36 publications

Quasi-periodic Pulsations in Solar and Stellar Flares: An Overview of Recent Results (Invited Review)

Quasi-periodic Pulsations in Solar and Stellar Flares: An Overview of Recent Results (Invited Review)

Determination of Transport Coefficients by Coronal Seismology of Flare-induced Slow-mode Waves: Numerical Parametric Study of a 1D Loop Model

A Compact Source for Quasi-periodic Pulsation in an M-class Solar Flare

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