Fast Magnetoacoustic Waves in a Fan Structure Above a Coronal Magnetic Null Point

Mészárosová, H.; Dudík, J.; Karlický, M.; Madsen, F. R. H.; Sawant, H. S.

doi:10.1007/s11207-013-0243-6

Cited by 27 publications

(25 citation statements)

References 52 publications

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“…In the present paper, using the first high time cadence images at 610 MHz from the GMRT, we have studied the decimetric radio activity associated with C-and M-class flares and a coronal mass ejection (CME) onset that occurred on 2015 June 20 and reported a decimetric radio source during the C-class flare to be located about 500″ away from the flaring site. The time cadence of the present GMRT observations is 0.5 s, while the earlier reported GMRT observations had a maximum time cadence of 16.9 s (Subramanian et al 2003), 2.11 s (Kundu et al 2006), or 1 s (Mészárosová et al 2013). The high time cadence images of GMRT 610 MHz during the C-class flare have also been used, in combination with the coronal images of extreme ultraviolet (EUV) and X-ray wavelengths, to investigate the genesis of radio-emitting electrons of decimetric sources and their temporal association with the Type III burst activity at metric wavelengths.…”

Section: Introductioncontrasting

confidence: 66%

Decimetric Emission 500″ Away from a Flaring Site: Possible Scenarios from GMRT Solar Radio Observations

Sawant

Janardhan

Yan³

et al. 2018

ApJ

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We present a study of decimetric radio activity using the first high time cadence (0.5 s) images from the Giant Meterwave Radio Telescope (GMRT) at 610 MHz associated with GOES C1.4-and M1.0-class solar flares and a coronal mass ejection (CME) onset that occurred on 2015 June 20. The high spatial resolution images from GMRT show a strong radio source during the C1.4 flare located ∼500″ away from the flaring site with no corresponding bright footpoints or coronal features nearby. In contrast, however, strong radio sources are found near the flaring site during the M1.0 flare and around the CME onset time. Weak radio sources located near the flaring site are also found during the maximum of the C1.4 flare activity that show a temporal association with metric Type III bursts identified by the Solar Broadband Radio Spectrometer at Yunnan Astronomical Observatory. Based on a multiwavelength analysis and magnetic potential field source surface extrapolations, we suggest that the source electrons of GMRT radio sources and metric Type III bursts originated from a common electron acceleration site. We also show that the strong GMRT radio source is generated by a coherent emission process, and its apparent location far from the flaring site is possibly due to the wave-ducting effect.

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Section: Introductioncontrasting

confidence: 66%

Decimetric Emission 500″ Away from a Flaring Site: Possible Scenarios from GMRT Solar Radio Observations

Sawant

Janardhan

Yan³

et al. 2018

ApJ

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“…Development of that study revealed that, for the perturbations of the sausage symmetry, an important factor is also the broadness of the initial spectrum in comparison with the cut-off wavelength (Nakariakov et al 2005) and that in some cases the wavelet spectrum of the resulting wave train could be almost monochromatic. A&A 560, A97 (2013) Similar tadpole wavelet features were detected in a number of flare-associated radio bursts observed in the decimetric band (Mészárosová et al 2009a(Mészárosová et al ,b,a, 2011Karlický et al 2011;Mészárosová et al 2013). In particular, observations with the spatial resolution revealed the appearance of signals with the tadpole wavelet signatures in a fan structure above a coronal magnetic null point .…”

Section: Introductionmentioning

confidence: 65%

Fast magnetoacoustic wave trains in magnetic funnels of the solar corona

Pascoe

Nakariakov

Kupriyanova

2013

A&A

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Context. Fast magneto-acoustic waves are highly dispersive in waveguides, so they can generate quasi-periodic wave trains if a localised, impulsive driver is applied. Such wave trains have been observed in the solar corona and may be of use as a seismological tool since they depend upon the plasma structuring perpendicular to the direction of propagation. Aims. We extend existing models of magnetoacoustic waveguides to consider the effects of an expanding magnetic field. The funnel geometry employed includes a field-aligned density structure. Methods. We performed 2D numerical simulations of impulsively generated fast magneto-acoustic perturbations. The effects of the density contrast ratio, density stratification, and spectral profile of the driver upon the excited wave trains were investigated. Results. The density structure acts as a dispersive waveguide for fast magneto-acoustic waves and generates a quasi-periodic wave train similar to previous models. The funnel geometry leads to generating additional wave trains that propagate outside the density structure. These newly discovered wave trains are formed by the leakage of transverse perturbations, but they propagate upwards owing to the refraction caused by the magnetic funnel. Conclusions. The results of our funnel model may be applicable to wave trains observed propagating in the solar corona. They demonstrate similar properties to those found in our simulations.

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“…For the developed stage of the evolution the quasi-periodic wave trains are best described using wavelet analysis (Nakariakov et al 2004), which reveals the "crazy tadpole" characteristic signature also seen in data for propagating fast wave trains detected with the Solar Eclipse Coronal Imaging System (SECIS; Katsiyannis et al 2003;Cooper et al 2003) and in decimetric band radio bursts A&A 569, A12 (2014) (e.g. Mészárosová et al 2009aMészárosová et al ,b, 2011Mészárosová et al , 2013Karlický et al 2011Karlický et al , 2013. Recent numerical studies have extended models for dispersive evolution of impulsively generated wave trains to include current sheets .…”

Section: Introductionmentioning

confidence: 89%

Observation of a high-quality quasi-periodic rapidly propagating wave train using SDO/AIA

Nisticò

Pascoe

Nakariakov

2014

A&A

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Context. We present a new event of quasi-periodic wave trains observed in EUV wavebands that rapidly propagate away from an active region after a flare. Aims. We measured the parameters of a wave train observed on 7 December 2013 after an M1.2 flare, such as the phase speeds, periods and wavelengths, in relationship to the local coronal environment and the energy sources. Methods. We compared our observations with a numerical simulation of fast magnetoacoustic waves that undergo dispersive evolution and leakage in a coronal loop embedded in a potential magnetic field. Results. The wave train is observed to propagate as several arc-shaped intensity disturbances for almost half an hour, with a speed greater than 1000 km s −1 and a period of about 1 min. The wave train followed two different patterns of propagation, in accordance with the magnetic structure of the active region. The oscillatory signal is found to be of high-quality, i.e. there is a large number (10 or more) of subsequent wave fronts observed. The observations are found to be consistent with the numerical simulation of a fast wave train generated by a localised impulsive energy release. Conclusions. Transverse structuring in the corona can efficiently create and guide high-quality quasi-periodic propagating fast wave trains.

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Fast Magnetoacoustic Waves in a Fan Structure Above a Coronal Magnetic Null Point

Cited by 27 publications

References 52 publications

Decimetric Emission 500″ Away from a Flaring Site: Possible Scenarios from GMRT Solar Radio Observations

Decimetric Emission 500″ Away from a Flaring Site: Possible Scenarios from GMRT Solar Radio Observations

Fast magnetoacoustic wave trains in magnetic funnels of the solar corona

Observation of a high-quality quasi-periodic rapidly propagating wave train using SDO/AIA

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