The Type IV Solar Radio Burst at Metre Wavelengths

Weiß, A.

doi:10.1071/ph630526

Cited by 46 publications

(16 citation statements)

References 11 publications

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“…First studies suggested that moving Type IV bursts are emitted by synchrotron or gyro-synchrotron emitting electrons that are trapped inside CME loops (Boischot & Clavelier 1968;Dulk 1973). However, since their discovery, a number of stationary Type IV radio sources have been observed that are believed to be generated by the plasma emission mechanism (Weiss 1963;Benz & Tarnstrom 1976), while some moving Type IV bursts have also been identified as plasma emission (Gary et al 1985). Bastian et al (2001) were the first to report the existence of a radio CME, which was observed as an ensemble of loop structures imaged by the Nançay Radioheliograph.…”

Section: Introductionmentioning

confidence: 99%

Variable emission mechanism of a Type IV radio burst

Morosan

Kilpua

Carley

et al. 2019

A&A

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Context. The Sun is an active star and the source of the largest explosions in the solar system, such as flares and coronal mass ejections (CMEs). Flares and CMEs are powerful particle accelerators that can generate radio emission through various emission mechanisms. Aims. CMEs are often accompanied by Type IV radio bursts that are observed as continuum emission in dynamic spectra at decimetric and metric wavelengths, but their emission mechanism can vary from event to event. Here, we aim to determine the emission mechanism of a complex Type IV burst that accompanied the flare and CME on 22 September 2011.Methods. We used radio imaging from the Nançay Radioheliograph, spectroscopic data from the e-Callisto network, ARTEMIS, Ondrejov, and Phoenix3 spectrometers combined with extreme-ultraviolet observations from NASA's Solar Dynamic Observatory to analyse the Type IV radio burst and determine its emission mechanism. Results. We show that the emission mechanism of the Type IV radio burst changes over time. We identified two components in the Type IV radio burst: an earlier stationary Type IV showing gyro-synchrotron behaviour, and a later moving Type IV burst covering the same frequency band. This second component has a coherent emission mechanism. Fundamental plasma emission and the electroncyclotron maser emission are further investigated as possible emission mechanisms for the generation of the moving Type IV burst. Conclusions. Type IV bursts are therefore complex radio bursts, where multiple emission mechanisms can contribute to the generation of the wide-band continuum observed in dynamic spectra. Imaging spectroscopy over a wide frequency band is necessary to determine the emission mechanisms of Type IV bursts that are observed in dynamic spectra.

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Section: Introductionmentioning

confidence: 99%

Variable emission mechanism of a Type IV radio burst

Morosan

Kilpua

Carley

et al. 2019

A&A

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“…This radiation was firstly recognized at meter wavelengths by Boischot (1957) and referred to the type IV burst. Weiss (1963) initiated to distinguish type IV bursts in height and movement of burst's sources. Subsequently, due to the fact that the radio emission was often related to the continuum at decimeter and centimeter wavelengths with differentiation of various phases within each individual event, this gave rise to overabundance of type IV categories and sub-categories.…”

Section: Introductionmentioning

confidence: 99%

A Decameter Stationary Type Iv Burst in Imaging Observations on 2014 September 6

Koval

Stanislavsky

Chen

et al. 2016

ApJ

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First-of-its-kind radio imaging of decameter solar stationary type IV radio burst has been presented in this paper. On 6 September 2014 the observations of type IV burst radio emission have been carried out with the two-dimensional heliograph based on the Ukrainian T-shaped radio telescope (UTR-2) together with other telescope arrays. Starting at ∼09:55 UT and throughout ∼3 hours, the radio emission was kept within the observational session of UTR-2. The interesting observation covered the full evolution of this burst, "from birth to death". During the event lifetime, two Cclass solar X-ray flares with peak times 11:29 UT and 12:24 UT took place. The time profile of this burst in radio has a double-humped shape that can be explained by injection of energetic electrons, accelerated by the two flares, into the burst source. According to the heliographic observations we suggest the burst source was confined within a high coronal loop, which was a part of a relatively slow coronal mass ejection. The latter has been developed for several hours before the onset of the event. Through analyzing about 1.5 × 10 6 of heliograms (3700 temporal frames with 4096 images in each frame that correspond to the number of frequency channels) the radio burst source imaging shows a fascinating dynamical evolution. Both space-based (GOES, SDO, SOHO, STEREO) data and various ground-based instrumentation (ORFEES, NDA, RSTO, NRH) records have been used for this study.

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“…Among them, the type IV (t-IV) radio burst is the most likely type related to the eruptive flux rope structure, while the type I burst is related to active regions (ARs) often in the absence of strong solar activities, the type II burst is attributed to energetic electrons accelerated at coronal shocks (see Feng et al 2013Feng et al , 2015Kong et al 2012;Chen et al 2014;Vasanth et al 2014;Du et al 2015 for latest studies), and type III and V bursts are given by energetic electrons accelerated at solar flares propagating outward along open field lines. The t-IV bursts are broadband continuum emission, further classified as the moving t-IV (t-IVm) and static t-IV bursts (Weiss 1963;Melrose, 1980), generally believed to be excited by energetic electrons trapped within certain magnetic structures, such as magnetic arches, loops, or plasmoid structures (Smerd & Dulk 1971;Vlahos et al 1982;Stewart 1985). Different emitting mechanisms have been proposed, including the synchrotron and gyro-synchrotron emission (Boischot 1957;Bastian & Gray 1997;Bastian et al 2001), the plasma emission (Duncan 1981;Stewart 1982;Ramesh et al 2013), and the electron cyclotron maser emission (Kujipers 1975;Lakhina & Buti 1985;Winglee & Dulk 1986).…”

Section: Introductionmentioning

confidence: 99%

An Eruptive Hot-Channel Structure Observed at Metric Wavelength as a Moving Type-Iv Solar Radio Burst

Vasanth

Chen

Feng

et al. 2016

ApJL

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Hot channel (HC) structure, observed in the high-temperature passbands of the AIA/SDO, is regarded as one candidate of coronal flux rope which is an essential element of solar eruptions. Here we present the first radio imaging study of an HC structure in the metric wavelength. The associated radio emission manifests as a moving type-IV (t-IVm) burst. We show that the radio sources co-move outwards with the HC, indicating that the t-IV emitting energetic electrons are efficiently trapped within the structure. The t-IV sources at different frequencies present no considerable spatial dispersion during the early stage of the event, while the sources spread gradually along the eruptive HC structure at later stage with significant spatial dispersion. The t-IV bursts are characterized by a relatively-high brightness temperature (∼ 10 7 − 10 9 K), a moderate polarization, and a spectral shape that evolves considerably with time. This study demonstrates the possibility of imaging the eruptive HC structure at the metric wavelength and provides strong constraints on the t-IV emision mechanism, which, if understood, can be used to diagnose the essential parameters of the eruptive structure.

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The Type IV Solar Radio Burst at Metre Wavelengths

Cited by 46 publications

References 11 publications

Variable emission mechanism of a Type IV radio burst

Variable emission mechanism of a Type IV radio burst

A Decameter Stationary Type Iv Burst in Imaging Observations on 2014 September 6

An Eruptive Hot-Channel Structure Observed at Metric Wavelength as a Moving Type-Iv Solar Radio Burst

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