New Evidence for a Coronal Mass Ejection-driven High Frequency Type II Burst near the Sun

Kumari, Anshu; Ramesh, R.; Kathiravan, C.; Gopalswamy, N.

doi:10.3847/1538-4357/aa72e7

Cited by 45 publications

(50 citation statements)

References 64 publications

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“…close to the west solar limb. Kumari et al (2017) analyzed the same shock event. In our paper we focused not only on the analysis of the type II burst and shock, but also on the analysis of its driver, i.e., the CME.…”

Section: Discussionmentioning

confidence: 99%

“…We present detailed analyses of the CME hot channel itself and its temporary and spatial relationship with the shock. Through the study of HC-shock relationship, we then can infer why the shock has an unusual high starting frequency and low formation height which was not included in Kumari et al (2017). The unusual large acceleration and high speed of the HC are the cause of high starting frequency.…”

Section: Discussionmentioning

confidence: 99%

“…Concerning the type II dynamic spectra, we used higherresolution data in which band split can be observed which allows us to further infer important parameters related to the shock than Kumari et al (2017). Therefore, the main conclusions are listed below:…”

Section: Discussionmentioning

confidence: 99%

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Properties of a Small-scale Short-duration Solar Eruption with a Driven Shock

Bao

Li²,

Lu³

et al. 2018

ApJ

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Large-scale solar eruptions have been extensively explored over many years. However, the properties of small-scale events with associated shocks have been rarely investigated. We present the analyses of a small-scale short-duration event originating from a small region. The impulsive phase of the M1.9-class flare lasted only for four minutes. The kinematic evolution of the CME hot channel reveals some exceptional characteristics including a very short duration of the main acceleration phase (< 2 minutes), a rather high maximal acceleration rate (∼50 km s −2 ) and peak velocity (∼1800 km s −1 ). The fast and impulsive kinematics subsequently results in a piston-driven shock related to a metric type II radio burst with a high starting frequency of ∼320 MHz of the fundamental band. The type II source is formed at a low height of below 1.1 R less than ∼ 2 minutes after the onset of the main acceleration phase. Through the band split of the type II burst, the shock compression ratio decreases from 2.2 to 1.3, and the magnetic field strength of the shock upstream region decreases from 13 to 0.5 Gauss at heights of 1.1 to 2.3 R . We find that the CME (∼ 4 × 10 30 erg) and flare (∼ 1.6 × 10 30 erg) consume similar amount of magnetic energy. The same conclusion for large-scale eruptions implies that small-and large-scale events possibly share the similar relationship between CMEs and flares. The kinematic particularities of this event are possibly related to the small footpoint-separation distance of the associated magnetic flux rope, as predicted by the Erupting Flux Rope model.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Properties of a Small-scale Short-duration Solar Eruption with a Driven Shock

Bao

Li²,

Lu³

et al. 2018

ApJ

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“…Stokes I, alone (Smerd, Sheridan, and Stewart, 1975;Gopalswamy and Kundu, 1990;Bastian et al, 2001;Vršnak et al, 2002;Mancuso et al, 2003;Cho et al, 2007;Kishore et al, 2016) or both the total and circularly polarized intensities, i.e. Stokes I and V (Dulk and Suzuki, 1980;Gary et al, 1985;Ramesh et al, 2010a;Ramesh, Kathiravan, and Narayanan, 2011;Tun and Vourlidas, 2013;Sasikumar Raja and Ramesh, 2013;Hariharan et al, 2014;2016b;Anshu et al, 2017). Note that we have mentioned only Stokes I and V emission here since differential Faraday rotation of the plane of polarization in the solar corona and Earth's ionosphere makes it impossible to observe the linear polarization (represented by Stokes Q and U ) within the typical observing bandwidths of ≈ 100 kHz (see for example Grognard and McLean, 1973.)…”

Section: Introductionmentioning

confidence: 99%

Strength of the Solar Coronal Magnetic Field – A Comparison of Independent Estimates Using Contemporaneous Radio and White-Light Observations

et al. 2017

Self Cite

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We estimated the coronal magnetic field strength (B) during the 23 July 2016 coronal mass ejection (CME) event using i) the flux rope structure of the CME in the whitelight coronagraph images and ii) the band splitting in the associated type II burst. No models were assumed for the coronal electron density (N (r)) used in the estimation. The results obtained using the above two independent methods correspond to different heliocentric distances (r) in the range ≈ 2.5 -4.5R ⊙ , but they show excellent consistency and could be fitted with a single power-law distribution of the type B(r) = 5.7r −2.6 G, which is applicable in the aforementioned distance range. The power law index (i.e. −2.6) is in good agreement with the results obtained in previous studies by different methods.

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“…Coronal mass ejections are usually associated with two main types of metric radio bursts categorised as type II and type IV bursts. Type II radio bursts (Roberts 1959;Klassen et al 2002;Kumari et al 2017) are characterised by emission bands in dynamic spectra, with a frequency ratio of 1 to 2, representing emission at the fundamental and harmonic of the plasma frequency (Nelson et al 1985). Herringbone bursts are often found together with type II bursts and are characterised by 'bursty' drifting lines in dynamic spectra superimposed on type II bands or occurring on their own (Cairns & Robinson 1987).…”

Section: Introductionmentioning

confidence: 99%

Moving solar radio bursts and their association with coronal mass ejections

Morosan

Kumari

Kilpua

et al. 2021

A&A

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Context. Solar eruptions, such as coronal mass ejections (CMEs), are often accompanied by accelerated electrons that can in turn emit radiation at radio wavelengths. This radiation is observed as solar radio bursts. The main types of bursts associated with CMEs are type II and type IV bursts that can sometimes show movement in the direction of the CME expansion, either radially or laterally. However, the propagation of radio bursts with respect to CMEs has only been studied for individual events. Aims. Here, we perform a statistical study of 64 moving bursts with the aim to determine how often CMEs are accompanied by moving radio bursts. This is done in order to ascertain the usefulness of using radio images in estimating the early CME expansion. Methods. Using radio imaging from the Nançay Radioheliograph (NRH), we constructed a list of moving radio bursts, defined as bursts that move across the plane of sky at a single frequency. We define their association with CMEs and the properties of associated CMEs using white-light coronagraph observations. We also determine their connection to classical type II and type IV radio burst categorisation. Results. We find that just over a quarter of type II and half of type IV bursts that occurred during the NRH observing windows in Solar Cycle 24 are accompanied by moving radio emission. All but one of the moving radio bursts are associated with white–light CMEs and the majority of moving bursts (90%) are associated with wide CMEs (> 60° in width). In particular, all but one of the moving bursts corresponding to type IIs are associated with wide CMEs; however, and unexpectedly, the majority of type II moving bursts are associated with slow white–light CMEs (< 500 km s−1). On the other hand, the majority of moving type IV bursts are associated with fast CMEs (> 500 km s−1). Conclusions. The observations presented here show that moving radio sources are almost exclusively associated with CMEs. The majority of events are also associated with wide CMEs, indicating that strong lateral expansion during the early stages of the eruption may play a key role in the occurrence of the radio emission observed.

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New Evidence for a Coronal Mass Ejection-driven High Frequency Type II Burst near the Sun

Cited by 45 publications

References 64 publications

Properties of a Small-scale Short-duration Solar Eruption with a Driven Shock

Properties of a Small-scale Short-duration Solar Eruption with a Driven Shock

Strength of the Solar Coronal Magnetic Field – A Comparison of Independent Estimates Using Contemporaneous Radio and White-Light Observations

Moving solar radio bursts and their association with coronal mass ejections

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