14 DAY TRIAL // On April 9, a coronal mass ejection weighing about a billion tons emerged from the surface of the Sun and, to the surprise of physicists, executed a cartwheel. At the same time, part of the mass of matter made a backflip in what now appears to be just a regular way for solar explosions to behave. "What a rare and exciting observation. It is showing us the secret inner workings of a process called 'magnetic reconnection' central to solar flares and CMEs," says Ed DeLuca from the Harvard-Smithsonian Center for Astrophysics.
The small video file seen here shows how a massive cloud of matter is being manipulated by the Sun's powerful magnetic field and spun at speeds exceeding 1,000 kilometers per hour. The image on the left, showing the cartwheel, was captured by the X-ray camera on board the Japanese Hinode orbiter, while the one next to it was recorded with the UV camera on NASA's TRACE spacecraft.
"We think we are seeing a twisted 'flux tube' of solar magnetism unfurl. One end of the tube spins clockwise, the other counterclockwise," DeLuca explained. By doing so, more explosive energy is released to propel the CME as far as possible from the Sun. When magnetic flux tubes break, the energy released can reach that of several hundred million hydrogen bombs, ejecting matter into space. "The really interesting developments came later," says solar physicist Leon Golub from the Center for Astrophysics, namely when the magnetic flux tubes start to reconnect. "This is the first time when we have witnessed a phase of magnetic reconnection never before seen in such detail," he added.
The reconnection of the magnetic flux tubes begins with a powerful X-ray emission, coming from the location on the surface where the CME originated. "This is a current sheet seen edge-on," says Golub. The current sheet is, in fact, the place where the reconnection takes place, as the opposite polarities of the magnetic field meet again.
Although Hinode observed several thousand of CMEs, this is the first time when the spacecraft captures a solar flare just behind the limb of the Sun, thus eliminating the bright emission of electromagnetic radiation and enabling it to make much lengthier observations on the CME.
Understanding solar eruption doesn't only provide with relevant information regarding the workings of the Sun, but it may also reveal the fundamental processes behind magnetic reconnection, a phenomenon that is also experienced in black holes, pulsars, galactic nuclei and planetary magnetospheres. It just happens that the Sun is the only body in the system where powerful magnetic reconnection phenomena take place.