Plasma Physics of the Local Cosmos (2004) / Chapter Skim
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5 Explosive Energy Conversion
5 Explosive Energy Conversion
Pages 57-64
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From page 57... ...
During the century following Carrington, solar flares and magnetic storms—both manifestations of magnetically mediated explosions, as mentioned—were topics at the center of interest of a new discipline that became known as solar-terrestrial relations. After Sputnik, Solar-terrestrial relations became Space physics, and space physicists, using data from spacecraft, began to expand their awareness of the explosive nature of magnetized cosmic plasmas.
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From page 58... ...
58 PLASMA PHYSICS OF THE LOCAL COSMOS FIGURE 5.1 Large coronal mass ejection from November 6,1997, as recorded by the LASCO C2 coronagraPh at 12 36 un versal time The white inner c rcle represents the solar disK which is hidden by the coronagraph's occulting disk (dark
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From page 59... ...
The underlying source of energy for all coronal activity is the mass motion in the subphotospheric convection region. Both the plasma beta and the magnetic Reynolds number' are much greater than unity in the photosphere and below and, consequently, the turbulent motions there tangle and stress magnetic field lines before and after the field emerges into the corona, so that the coronal field contains a large amount of free energy that can be released through magnetic reconnection processes that alter its topology It is the free energy in these stressed coronal magnetic fields that powers (perhaps with intermediate steps)
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From page 60... ...
Klimchuk Theory of coronal mass ejections, pp. 143-157 in Space Wecrher, Geophysical Monograph 125, P
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From page 61... ...
The Felicity of the structure is then bodily removed in the Chile, and with its loss from the coronal system the rest of the stored energy can, in principle, be released 2 Outstanding Questions About Storage-Release in the Sun's Corona · How is magnetic free energy built up and stored in the coronal For example, does it arise primarily from photospheric motions, or from the emergence of an already-twisted magnetic field from the solar interiori · How is this magnetic free energy then converted into heating in solar flares and or kinetic energy in coronal mass ejectionsi . How significant is mass to the Chile systemi .
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From page 62... ...
The stored magnetic energy is thereby converted into heat and plasma kinetic energy in the form of enhanced plasma flows and energetic particle injections. The field lines earthward of the newly formed neutral line assume a dipolar configuration and flow around toward the dayside, replenishing the magnetic flux that had been stripped away by magnetopause reconnection.
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From page 63... ...
In the current-disruption model, substorm breakup begins nearer Earth, at distances between 7 and 12 Earth radii, with the disruption of a very thin current sheet formed within the much thicker plasma sheet, while fast reconnection in the mid-tail develops later in the expansion phase. Observations have yielded conflicting evidence on whether the physical cause of breakup is in the near-Earth or mid-tail plasma sheet.
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From page 64... ...
For example, a huge stellar eruption has been observed in the very young binary system of XZ-Tauri AB.4 Eruptions have also been observed in a classic T-Tauri star and its stellar accretion disk that have been speculated to be akin to coronal mass ejections s Moreover, the M-dwarfs, with their monstrous flares (which can be hundreds of times brighter than the brightest solar flares) and equally monstrous starspots (covering more than half the stellar diameter)
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