Electron beams generated by shock waves in the solar corona

Mann, G.; Klassen, A.

doi:10.1051/0004-6361:20034396

Cited by 97 publications

(103 citation statements)

References 38 publications

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“…and 10:24). This observation agrees with the fact that a type-III radio burst is caused by energetic electrons (>10 keV) moving along open magnetic-field lines [42,43]. Note that the open-field-line geometry is important because, for such a geometry, a bump-in-tail distribution for electrons can quickly develop, which in turn can cause the excitation of Langmuir waves and, through nonlinear interaction, radio waves.…”

Section: Event Identification and Analysissupporting

confidence: 86%

Coalescence of Macroscopic Magnetic Islands and Electron Acceleration from STEREO Observation

Song

Chen

et al. 2012

Phys. Rev. X

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Magnetic reconnection is a fundamental plasma process. Recent theoretical studies and numerical simulations have suggested that electrons can be efficiently accelerated in contracting magnetic islands and when magnetic islands coalesce. Using data from the STEREO spacecraft, we report in this article the first observation of macroscopic magnetic-island coalescence and a possible splitting, and the associated electron acceleration. On 24 May 2010, two magnetic islands were observed by both the STEREO-A and STEREO-B spacecraft to propagate out along the current sheet behind a coronal mass ejection (CME) and merge. Electron acceleration to above 10 keVis inferred through the observation of a type-III-like radio burst. The acceleration process occurred at a macroscopic scale, likely during the merging of the two magnetic islands. Our observation of the magnetic-island coalescence is supported by a 2.5-D axisymmetric magnetohydrodynamic simulation of CME in which the merging of post-CME magnetic islands is clearly identified.

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Section: Event Identification and Analysissupporting

confidence: 86%

Coalescence of Macroscopic Magnetic Islands and Electron Acceleration from STEREO Observation

Song

Chen

et al. 2012

Phys. Rev. X

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“…It appears as rapidly drifting (some 10 MHz/s) stripes of enhanced radio emission shooting up from the "backbone" (i.e., the main type II trace in the frequency-time plot) towards both high and low frequencies (see Figure 19 from Mann and Klassen, 2005). These "herringbones," as Roberts (1959) called them, are regarded as signatures of upward and downward pointed electron beams, which are accelerated by the shock waves associated with the "backbone".…”

Section: Metric Type II Radio Burstsmentioning

confidence: 99%

Space Weather: The Solar Perspective

Schwenn

2006

Living Rev. Solar Phys.

425

335

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The term space weather refers to conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and that can affect human life and health. Our modern hi-tech society has become increasingly vulnerable to disturbances from outside the Earth system, in particular to those initiated by explosive events on the Sun: Flares release flashes of radiation that can heat up the terrestrial atmosphere such that satellites are slowed down and drop into lower orbits, solar energetic particles accelerated to near-relativistic energies may endanger astronauts traveling through interplanetary space, and coronal mass ejections are gigantic clouds of ionized gas ejected into interplanetary space that after a few hours or days may hit the Earth and cause geomagnetic storms. In this review, I describe the several chains of actions originating in our parent star, the Sun, that affect Earth, with particular attention to the solar phenomena and the subsequent effects in interplanetary space.

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“…This mechansim was studied in a quantitative manner by Mann et al (2006Mann et al ( , 2009. Other mechanisms are the acceleration at shock waves as a result of a blast wave and/or driven by a coronal mass ejection (Holman & Pesses 1983;Mann & Classen 1995;Mann & Klassen 2005), by stochastic acceleration via wave particle interaction in the highly turbulent flare region (Melrose 1994;Miller et al 1996;Miteva & Mann 2007), and by acceleration in collapsing magnetic traps (Somov & Kosugi 1997;Karlicky & Kosugi 2004).…”

Section: Introductionmentioning

confidence: 99%

Budget of energetic electrons during solar flares in the framework of magnetic reconnection

Mann

Warmuth

2011

A&A

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Context. Among other things, solar flares are accompanied by the production of energetic electrons as seen in the nonthermal radio and X-ray radiation of the Sun. Observations of the RHESSI satellite show that 10 32 −10 36 nonthermal electrons are produced per second during flares. They are related to an energy flux in the range 10 18 −10 22 W. These electrons play an important role, since they carry a substantial part of the energy released during a flare. Aims. In which way so many electrons are accelerated up to high energies during a fraction of a second is still an open question. By means of radio and hard X-ray data, we investigate under which conditions this acceleration happens in the corona. Methods. The flare is considered in the framework of magnetic reconnection. The conditions in the acceleration region in the corona are deduced by using the conservation of the total electron number and energy. Results. In the inflow region of the magnetic reconnection site, there are typical electron number densities of about 2.07×10 9 cm −3 and magnetic fields of about 46 G. These are regions with high Alfvén speeds of about 2200 km s −1 . Then, sufficient energetic electrons (as required by the RHESSI observations) are only generated if the plasma inflow towards the reconnection site has Alfvén-Mach numbers in the range 0.1−1, which can lead to a super-Alfvénic outflow with speeds up to 3100 km s −1 .

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Electron beams generated by shock waves in the solar corona

Cited by 97 publications

References 38 publications

Coalescence of Macroscopic Magnetic Islands and Electron Acceleration from STEREO Observation

Coalescence of Macroscopic Magnetic Islands and Electron Acceleration from STEREO Observation

Space Weather: The Solar Perspective

Budget of energetic electrons during solar flares in the framework of magnetic reconnection

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