Vele di massa coronale in uno studio NASA

In una spettacolare ricostruzione tridimensionale, gli scienziati della NASA hanno pubblicato su Nature Communications (pdf disponibile, ma affrettatevi) uno studio sulla propagazione nello spazio delle eiezioni di massa coronale. Queste masse di materiale particellare solare percorrono sulla traiettoria sole-terra un tracciato non lineare e iniscono per abbattersi come un colpo di frusta sul nostro sistema geomagnetico. La materia coronale si stende come una vela spaziale, si gonfia, accelera e colpisce con violenza.

I dati utilizzati per questo studio provengono dalla missione STEREO e sono stati rielaborati dal supercomputer del Trinity College di Dublino. L'articolo che segue è stato pubblicato su Science News.

Solar Storms can Change Directions, Surprising Forecasters

Sept. 21, 2010: Solar storms don't always travel in a straight line. But once they start heading in our direction, they can accelerate rapidly, gathering steam for a harder hit on Earth's magnetic field.

So say researchers who have been using data from NASA's twin STEREO spacecraft to unravel the 3D structure of solar storms. Their findings are presented in today's issue of Nature Communications.

"This really surprised us," says co-author Peter Gallagher of Trinity College in Dublin, Ireland. "Solar coronal mass ejections (CMEs) can start out going one way—and then turn in a different direction."

The result was so strange, at first they thought they'd done something wrong. After double- and triple-checking their work on dozens of eruptions, however, the team knew they were onto something.

"Our 3D visualizations clearly show that solar storms can be deflected from high solar latitudes and end up hitting planets they might otherwise have missed," says lead author Jason Byrne, a graduate student at the Trinity Center for High Performance Computing.

The key to their analysis was an innovative computing technique called "multiscale image processing." Gallagher explains:

"'Multiscale processing' means taking an image and sorting the things in it according to size. Suppose you're interested in race cars. If you have a photo that contains a bowl of fruit, a person, and a dragster, you could use multiscale processing to single out the race car and study its characteristics."

In medical research, multiscale processing has been used to identify individual nuclei in crowded pictures of cells. In astronomy, it comes in handy for picking galaxies out of a busy star field. Gallagher and colleagues are the first to refine and use it in the realm of solar physics.

"We applied the multiscale technique to coronagraph data from NASA's twin STEREO spacecraft," Gallagher continues. "Our computer was able to look at starry images cluttered with streamers and bright knots of solar wind and zero in on the CMEs."

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