Flares
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X-class flare in active region 10930 (1/2)
Hinode Broadband Filter Imager
Who said that magnetic field lines never cross each other? The Sun is the perfect scenario to observe magnetic field lines crossing each other in a physical process called reconnection. During this process, magnetic field lines in the solar atmosphere can meet at different directions and angles. Once they clash, their magnetic energy is converted into enormous heating and kinetic energy of the surrounding plasma, which is then ejected in different directions at huge velocities. Big amounts of energy are released during reconnection, producing "fireworks" and the amazing activity we can observe on the Sun. After reconnection, the magnetic field lines reconfigure into a more relaxed energy state.
Reconnection can happen anywhere in the solar atmosphere, from the lowest layers (the photosphere) to the highest layers (transition region and corona) and can produce very energetic flares or coronal mass ejections, where tons of mass are ejected into the interplanetary space. Reconnection usually happens when new magnetic flux emerges into the Sun's surface. The new magnetic loops rise through the solar atmosphere and interact (reconnect) with the pre-existing loops or with themselves.
The movies show two adjacent sunspots observed by the Japanese satellite Hinode on 2006 December 13 in the photosphere (G band) and the lower chromosphere (Ca II H line). The lower sunspot seems to rotate counter clockwise with respect to the upper sunspot. A lot of shear occurs in the interface between the two sunspots, electric currents are created and magnetic tension is accumulated as the lower sunspot twists. Eventually that magnetic energy is released in the form of a huge X3.4 class flare that ejects plasma and energy in all directions. This is better seen in the Ca II H line, but the flare was so intense that it was also visible in the photosphere (G band).
The European Solar Telescope will help solar researchers to discern the ultimate details of reconnection at the finest spatial scales thanks to its superb spatial resolution. EST will observe the lower layers of the solar atmosphere, namely the photosphere and the chromosphere, simultaneously to study the magnetic coupling between these two systems.
To download the movie, click HERE
Movie credit: NASA's Goddard Space Flight Center Scientific Visualization Studio
Text credit: Ada Ortiz (ITA, University of Oslo)
Observations: Hinode (ISAS/JAXA, NAOJ, NASA, STFC, ESA)
Publication: Kubo et al., 2007, Publications of the Astronomical Society of Japan, 59, S779-S784
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Source: NASA's Goddard Space Flight Center Scientific Visualization Studio