Investigation of the Coronal Magnetic Field Using a Type II Solar Radio Burst

Vasanth, V.; Umapathy, Siva; Vršnak, Bojan; Žic, Tomislav; Prakash, Om

doi:10.1007/s11207-013-0318-4

Cited by 34 publications

(23 citation statements)

References 24 publications

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“…The adoption of the central frequencies of the lower-frequency branch to estimate the heights of the radio source has accounted for our higher values. However, our results are different from those obtained by Vasanth et al (2014), who found a sharp decrease in the shock speed, from 820 km s −1 to 580 km s −1 , for 05:39 -05:41 UT (three and five minutes after the onset of the type II emission). Our estimates of the frequency drift rate using exponential fits on the intensity maxima of the radio emission may be responsible for these differences.…”

Section: Resultscontrasting

confidence: 99%

Solar type II radio bursts associated with CME expansions as shown by EUV waves

Cunha-Silva

Fernandes

Selhorst

2015

A&A

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Aims. We investigate the physical conditions of the sources of two metric type II bursts associated with coronal mass ejection (CME) expansions with the aim of verifying the relationship between the shocks and the CMEs by comparing the heights of the radio sources and of the extreme-ultraviolet (EUV) waves associated with the CMEs. Methods. The heights of the EUV waves associated with the events were determined in relation to the wave fronts. The heights of the shocks were estimated by applying two different density models to the frequencies of the type II emissions and compared with the heights of the EUV waves. For the event on 13 June 2010 that included band-splitting, the shock speed was estimated from the frequency drifts of the upper and lower frequency branches of the harmonic lane, taking into account the H/F frequency ratio f H / f F = 2. Exponential fits on the intensity maxima of the frequency branches were more consistent with the morphology of the spectrum of this event. For the event on 6 June 2012 that did not include band-splitting and showed a clear fundamental lane on the spectrum, the shock speed was directly estimated from the frequency drift of the fundamental emission, determined by linear fit on the intensity maxima of the lane. For each event, the most appropriate density model was adopted to estimate the physical parameters of the radio source. Results. The event on 13 June 2010 had a shock speed of 590-810 km s −1 , consistent with the average speed of the EUV wave fronts of 610 km s −1 . The event on 6 June 2012 had a shock speed of 250-550 km s −1 , also consistent with the average speed of the EUV wave fronts of 420 km s −1 . For both events, the heights of the EUV wave revealed to be compatible with the heights of the radio source, assuming a radial propagation of the type-II-emitting shock segment.

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Section: Resultscontrasting

confidence: 99%

Solar type II radio bursts associated with CME expansions as shown by EUV waves

Cunha-Silva

Fernandes

Selhorst

2015

A&A

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“…The value is consistent with previous work (Vršnak et al 2002;Mancuso & Garzelli 2013;Kouloumvakos et al 2014;Vasanth et al 2014;Zucca et al 2014b), but it is more closely constrained in the present event by the combination of the type II spectrum and the stereoscopic CME modeling. Similar Mach numbers were derived from white-light observations (Bemporad & Mancuso 2010, 2011.…”

Section: Cme Shocksupporting

confidence: 92%

Coronal mass ejection-related particle acceleration regions during a simple eruptive event

Salas-Matamoros

Klein

Rouillard

2016

A&A

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An intriguing feature of many solar energetic particle (SEP) events is the detection of particles over a very extended range of longitudes in the heliosphere. This may be due to peculiarities of the magnetic field in the corona, to a broad accelerator, to cross-field transport of the particles, or to a combination of these processes. The eruptive flare on 26 April 2008 provided an opportunity to study relevant processes under particularly favourable conditions since it occurred in a very quiet solar and interplanetary environment. This enabled us to investigate the physical link between a single well-identified coronal mass ejection (CME), electron acceleration as traced by radio emission, and the production of SEPs. We conduct a detailed analysis, which combines radio observations (Nançay Radio Heliograph and Nançay Decametre Array, Wind/Waves spectrograph) with remote-sensing observations of the corona in extreme ultraviolet (EUV) and white light, as well as in situ measurements of energetic particles near 1AU (SoHO and STEREO spacecraft). By combining images taken from multiple vantage points, we were able to derive the time-dependent evolution of the 3D pressure front that was developing around the erupting CME. Magnetic reconnection in the post-CME current sheet accelerated electrons, which remained confined in closed magnetic fields in the corona, while the acceleration of escaping particles can be attributed to the pressure front ahead of the expanding CME. The CME accelerated electrons remotely from the parent active region, owing to the interaction of its laterally expanding flank, which was traced by an EUV wave, with the ambient corona. SEPs detected at one STEREO spacecraft and SoHO were accelerated later, when the frontal shock of the CME intercepted the spacecraft-connected interplanetary magnetic field line. The injection regions into the heliosphere inferred from the radio and SEP observations are separated in longitude by about 140• . The observations for this event show that it is misleading to interpret multi-spacecraft SEP measurements in terms of one acceleration region in the corona. The different acceleration regions are linked to different vantage points in the interplanetary space.

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“…В настоящее время не вызывает сомнений, что солнечные радиовсплески II типа генерируются в области фронта ударных волн [1][2][3][4]. Часто на динамических спектрах можно наблюдать две близко расположенные полосы, ведущие себя схожим образом как по интенсивности, так и скорости дрейфа на протяжении десятков минут [2][3][4][5][6][7].…”

Section: Doi: 1031725/0552-5829-2019-427-430unclassified

On the Splitting of Bands on the Dynamic Spectra of Type Ii Radio Bursts

Tsap¹,

Исаева²,

Kopylova³

2019

Proceedings of the 23rd All-Russia Conference on Solar and Solar-Terrestrial Physics

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Based on the analysis of dynamic spectra of solar flare radiation in the meter wavelength range obtained with RSTN the evolution of the split parameters of type II solar radio bursts is considered. The relative band-splitting behaves non-monotonically and its values vary in a wide range from 0.1 to 3. This can be explained by the generation of electromagnetic waves near fundamental and second harmonics of plasma frequency and the density jump in the vicinity of a shock front. It has been shown that the joint action of these two mechanisms can result in the change of the relative band-splitting from 0 to 3. Diagnostics of the solar coronal plasma and magnetic field within the framework of a model suggested the relationship between the band-splitting and the density jump is discussed.

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Investigation of the Coronal Magnetic Field Using a Type II Solar Radio Burst

Cited by 34 publications

References 24 publications

Solar type II radio bursts associated with CME expansions as shown by EUV waves

Solar type II radio bursts associated with CME expansions as shown by EUV waves

Coronal mass ejection-related particle acceleration regions during a simple eruptive event

On the Splitting of Bands on the Dynamic Spectra of Type Ii Radio Bursts

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