The Coronal Mass Ejection of 1998 April 20: Direct Imaging at Radio Wavelengths

Bastian, T. S.; Pick, M.; Kerdraon, A.; Maia, D.; Vourlidas, A.

doi:10.1086/323421

Cited by 185 publications

(176 citation statements)

References 18 publications

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“…The close association between such a continuum and CMEs was also found by Aurass et al (1999). Bastian et al (2001) first discovered a radio CME on 20 April 1998 using the NRH observation. Its parameters are in agreement with the white light CME observed by LASCO.…”

Section: Event On 20 April 1998supporting

confidence: 63%

“…Later, during the type II occurrence they are ejected in the IP medium without signatures in the low corona, particularly in the radio domain and in the SXR derivative. The observation of the radio CME on 20 April 1998 (Bastian et al 2001) occurring due to synchrotron radiation of relativistic electrons trapped in closed magnetic field structures at the heights of some solar radii supports this scenario.…”

Section: Discussionmentioning

confidence: 80%

“…It is important to note that the relativistic electrons were released without any radio emission from microwaves down to the metric domain. Only a radio continuum (09:57-10:21 SRT, maximum at 10:05 SRT, at 100-400 MHz) associated with the radio CME is seen shortly before the electron event onset (Bastian et al 2001). The SXR flux, its derivative and the HXR observations show no enhancements or indications of acceleration in the low corona during the onset of the electron event (Fig.…”

Section: Event On 20 April 1998mentioning

confidence: 94%

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Solar energetic electron events and coronal shocks

Klassen

Bothmer

Mann

et al. 2002

A&A

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Abstract. Mildly relativistic electrons appear during the solar energetic particle events. A detailed investigation on the origin of such electrons is presented for four particlular solar events. The mildly relativistic electrons have been detected at energies of 0.25-0.7 MeV by COSTEP/SOHO and below 0.392 MeV by Wind 3-DP experiments. Coronal shocks associated with these electron events are identified from the metric-to-decametric solar type II radio bursts. All selected events were associated with solar activity at western longitudes, so that the magnetic footpoints connecting the spacecraft with the Sun were close to the flare/shock/CME site. The associated type II bursts were accompanied by so-called shock accelerated (SA) type III bursts appearing to be emerging from the type II emission site. We found: (1) that all of the 0.25-0.7 MeV electron events were released during or after, but never simultaneously with the onset of type II bursts and CMEs. The time delay between the type II burst onset and the release of the mildly relativistic electrons is in the range of 11.5−45 min; (2) that the mildly relativistic electrons were released rather at the end of SA type III bursts or somewhat later; (3) that the mildly relativistic electrons were released when the associated type II burst and the CME reached a certain height (h ∼ 1-4 Rs) above the photosphere. For the four events studied, it is concluded that mildly relativistic electrons at 0.25-0.7 MeV energies measured in the interplanetary medium from solar energetic particle events are accelerated by coronal shock waves, commonly in association with white-light CMEs.

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Section: Event On 20 April 1998supporting

confidence: 63%

Section: Discussionmentioning

confidence: 80%

Section: Event On 20 April 1998mentioning

confidence: 94%

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Solar energetic electron events and coronal shocks

Klassen

Bothmer

Mann

et al. 2002

A&A

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“…2). Gyro-synchrotron emission from electrons in the overlying flux rope was also reported in other events (Bastian et al 2001;Maia et al 2007;Bain et al 2014), but it can only be detected with imaging observations.…”

Section: An Interpretation Of Particle Acceleration During the Secondmentioning

confidence: 60%

The relativistic solar particle event of 2005 January 20: origin of delayed particle acceleration

Klein

Masson

Bouratzis

et al. 2014

A&A

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Context. The highest energies of solar energetic nucleons detected in space or through gamma-ray emission in the solar atmosphere are in the GeV range. Where and how the particles are accelerated is still controversial. Aims. We search for observational information on the location and nature of the acceleration region(s) by comparing the timing of relativistic protons detected on Earth and radiative signatures in the solar atmosphere during the particularly well-observed 2005 Jan. 20 event.Methods. This investigation focusses on the post-impulsive flare phase, where a second peak was observed in the relativistic proton time profile by neutron monitors. This time profile is compared in detail with UV imaging and radio spectrography over a broad frequency band from the low corona to interplanetary space. Results. It is shown that the late relativistic proton release to interplanetary space was accompanied by a distinct new episode of energy release and electron acceleration in the corona traced by the radio emission and by brightenings of UV kernels. These signatures are interpreted in terms of magnetic restructuring in the corona after the coronal mass ejection passage. Conclusions. We attribute the delayed relativistic proton acceleration to magnetic reconnection and possibly to turbulence in largescale coronal loops. While Type II radio emission was observed in the high corona, no evidence of a temporal relationship with the relativistic proton acceleration was found.

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“…However, no counterpart to white-light CMEs has been observed in other wavelength regimes, mainly due to sensitivity limits. A first direct imaging of an expanding CME loop at radio wavelengths was reported by Bastian et al (2001), detected in form of nonthermal synchrotron emission produced by electrons with energies of ≈0.5-5 MeV interacting with magnetic fields of ≈0.1 G in the heliosphere.…”

Section: First Radio Image Of a Coronal Mass Ejectionmentioning

confidence: 99%

Astrophysics in 2001

Trimble¹,

Aschwanden²

2002

PUBL ASTRON SOC PAC

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ABSTRACT. During the year, astronomers provided explanations for solar topics ranging from the multiple personality disorder of neutrinos to cannibalism of CMEs (coronal mass ejections) and extrasolar topics including quivering stars, out-of-phase gaseous media, black holes of all sizes (too large, too small, and too medium), and the existence of the universe. Some of these explanations are probably probably true, though the authors are not betting large sums on any one. The data ought to remain true forever, though this requires a careful definition of "data" (think of the Martian canals).

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The Coronal Mass Ejection of 1998 April 20: Direct Imaging at Radio Wavelengths

Cited by 185 publications

References 18 publications

Solar energetic electron events and coronal shocks

Solar energetic electron events and coronal shocks

The relativistic solar particle event of 2005 January 20: origin of delayed particle acceleration

Astrophysics in 2001

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