Theoretical Investigation of the Onsets of Type II Radio Bursts during Solar Eruptions

Lin, Jin‐Ming; Mancuso, Salvatore; Vourlidas, A.

doi:10.1086/506599

Cited by 57 publications

(56 citation statements)

References 66 publications

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“…This is consistent with the theoretical investigation of Lin et al (2006) and observations of Reiner et al (2003), Vourlidas et al (2003), Cho et al (2008), and Ramesh et al (2010). However, it is not clear how general our conclusion is for multiple or non-CME nose shocks in the low corona.…”

Section: Discussionsupporting

confidence: 88%

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Relationship between multiple type II solar radio bursts and CME observed by STEREO/SECCHI

Cho

Bong

Moon

et al. 2011

A&A

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Aims. Two or more type II bursts are occasionally observed in close time sequence during solar eruptions, which are known as multiple type II bursts. The origin of the successive burst has been interpreted in terms of coronal mass ejections (CMEs) and/or flares. Detailed investigations of the relationship between CMEs and the bursts enable us to understand the nature of the multiple type II bursts. In this study, we examine multiple type II bursts and compare their kinematics with those of a CME occurring near the time of the bursts. Methods. To do this, we selected multiple type II bursts observed by the Culgoora radiospectrographs and a limb CME detected in the low corona field of view (1.4−4 R s ) of a STEREO/SECCHI instrument on December 31, 2007. To determine the 3D kinematics of the CME, we applied the stereoscopic technique to the STEREO/SECCHI data. Results. Our main results are as follows: (1) the multiple type II bursts occurred successively at ten minute intervals and displayed various emission structures and frequency drifting rates; (2) near the time of the bursts, the CME was observed by STEREO and SOHO simultaneously, but no evidence of other CMEs was detected; (3) inspection of the 3D kinematics of the CME using the stereoscopic observation by STEREO/SECCHI revealed that the CME propagated along the eastward radial direction as viewed from the Earth; (4) very close time and height associations were found between the CME nose and the first type II burst, and between CME-streamer interaction and the second type II burst. Conclusions. On the basis of these results, we suggest that a single shock in the leading edge of the CME could be the source of the multiple type II bursts and support the notion that the CME nose and the CME-streamer interaction are the two main mechanisms able to generate the bursts.

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Section: Discussionsupporting

confidence: 88%

“…It is likely that the relatively slow CME flank could also form a shock at the location of the streamer interface because of the low local Alfvén speed at the high density streamer. This would agree with the recent theoretical investigation of the type II burst onset by Lin et al (2006).…”

Section: Second Type II Burstsupporting

confidence: 93%

Relationship between multiple type II solar radio bursts and CME observed by STEREO/SECCHI

Cho

Bong

Moon

et al. 2011

A&A

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“…Plasma instabilities and the associated consequences could be one source of these structures, and the inhomogeneities of plasma and magnetic field in both space and time during the reconnection process could be another one. Interested readers are referred to Kliem et al (2000), Shibata and Tanuma (2001), Lin et al (2006), Liu et al (2010), and so on.…”

Section: Reasonableness Of Large Values Of Cs Thickness and Resistivitymentioning

confidence: 99%

Review on Current Sheets in CME Development: Theories and Observations

et al. 2015

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We introduce how the catastrophe model for solar eruptions predicted the formation and development of the long current sheet (CS) and how the observations were used to recognize the CS at the place where the CS is presumably located. Then, we discuss the direct measurement of the CS region thickness by studying the brightness distribution of the CS region at different wavelengths. The thickness ranges from 10 4 km to about 10 5 km at heights between 0.27 and 1.16 R from the solar surface. But the traditional theory indicates that the CS is as thin as the proton Larmor radius, which is of order tens of meters in the corona. We look into the huge difference in the thickness between observations and theoretical expectations. The possible impacts that affect measurements and results are studied, and physical causes leading to a thick CS region in which reconnection can still occur at a reasonably fast rate are analyzed. Studies in both theories and observations suggest that the difference between the true value and the apparent value of the CS thickness is not significant as long as the CS could be recognised in observations. We review observations that show complex structures and flows inside the CS region and present recent numerical modelling results on some aspects of these structures. Both observations and numerical experiments indicate that the downward reconnection outflows are usually slower than the upward ones in the same eruptive event. Numerical simulations show that the complex structure inside CS and its temporal behavior as a result of turbulence and the Petschek-type slow-mode shock could probably account for the thick CS and fast reconnection. But whether the CS itself is that thick still remains unknown since, for the time being, we cannot measure the electric current directly in that region. We also review the most recent laboratory experiments of reconnection driven by energetic laser beams, and discuss some important topics for future works.

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“…As the density distribution and magnetic field configuration in the accretion disk corona around a black hole are poorly understood, we follow Yuan et al (2009) and assume that an accretion disk corona is similar to the solar corona. The results are not expected to change very much using this assumption or an alternative, provided that the local Alfvén speed near the current sheet does not decrease drastically with height within the ejection region of the plasmoid (see Lin et al 2006). This condition is satisfied for a planar geometry as in the corona above an accretion disk.…”

Section: Evolution Of the Plasmoid Velocitymentioning

confidence: 96%

Variations in emission from episodic plasmoid ejecta around black holes

Younsi¹,

Wu²

2015

Mon. Not. R. Astron. Soc.

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The X-ray and radio flares observed in X-ray binaries and active galactic nuclei (AGN) are attributed to energetic electrons in the plasma ejecta from the accretion flows near the black hole in these systems. It is argued that magnetic reconnection could occur in the coronae above the accretion disk around the black hole, and that this drives plasmoid outflows resembling the solar coronal mass ejection (CME) phenomenon. The X-ray and radio flares are emission from energetic electrons produced in the process. As the emission region is located near the black hole event horizon, the flare emission would be subject to special-and general-relativistic effects. We present calculations of the flaring emission from plasmoids orbiting around a black hole and plasmoid ejecta launched from the inner accretion disk when general-relativistic effects are crucial in determining the observed time-dependent properties of the emission. We consider fully general-relativistic radiative transfer calculations of the emission from evolving ejecta from black hole systems, with proper accounting for differential arrival times of photons emitted from the plasmoids, and determine the emission lightcurves of plasmoids when they are in orbit and when they break free from their magnetic confinement. The implications for interpreting time-dependent spectroscopic observations of flaring emission from accreting black holes are discussed.

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Theoretical Investigation of the Onsets of Type II Radio Bursts during Solar Eruptions

Cited by 57 publications

References 66 publications

Relationship between multiple type II solar radio bursts and CME observed by STEREO/SECCHI

Relationship between multiple type II solar radio bursts and CME observed by STEREO/SECCHI

Review on Current Sheets in CME Development: Theories and Observations

Variations in emission from episodic plasmoid ejecta around black holes

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