Intergalactic Hiccups and Formulas for Panic
Magnetar Does A Gigantic Stellar ‘Hiccup’ - Science Daily - 06/04/2007
Astronomers using data from several X-ray satellites have caught a magnetar – the remnant of a massive star with an incredibly strong magnetic field – in a sort of giant cosmic blench.
When it comes to eerie astrophysical effects, the neutron stars commonly known as magnetars are hard to beat. The massive remnants of exploded stars, magnetars are the size of mountains but weigh as much as the sun, and have magnetic fields hundreds of trillions of times more powerful than the Earth’s, which pushes our compass needles north.
Now astrophysicists have managed to catch a recently discovered magnetar in a sort of giant cosmic hiccup that still has them puzzled. In multiple reports in the Astrophysical Journal and Monthly Notices of the Royal Astronomical Society, the researchers describe the behaviour of this body, located in a star cluster about 15 000 light-years away in the Ara constellation in the southern hemisphere. The magnetar goes by the unwieldy official name CXOU J164710.2-455216, or more informally, the ‘Westerlund 1 magnetar.’
“We only know of about a dozen magnetars,” says Michael Muno, a scientist at the California Institute of Technology’s Space Radiation Laboratory, and the original discoverer of the magnetar in 2005. “In brief, what we observed was a seismic event on the magnetar, which tells us a lot about the stresses these objects endure.”
Formula for Panic: Crowd-motion findings may prevent stampedes. - Science News - 07/04/2007
Wherever dense crowds gather, an eruption of panic can have deadly consequences, as in the stampede that killed hundreds during a mass pilgrimage to Mecca in 2006. With methods from the physics of fluids, scientists have now dissected the events of that tragic day and come up with recommendations that may have contributed to making this year’s pilgrimage proceed smoothly.
Every year toward the end of the week-long Hajj pilgrimage, millions of pilgrims visit the place in the desert outside Mecca, Saudi Arabia, where Abraham is said to have thrown stones at the devil. Every able-bodied Muslim is supposed to make the trip at least once. When they arrive, pilgrims throw pebbles at three walls, which symbolize three apparitions of the Evil One.
Catastrophic stampedes have periodically afflicted the event. The most recent one, on Jan. 12, 2006, killed 345 people and injured 289.
In collaboration with Saudi authorities, physicists at Dresden University of Technology in Germany studied video recordings of the 2006 stampede. They wrote visual-recognition software to track and measure the motion of individuals in the crowd and, by following those individuals, analyzed the crowd’s movements as the disaster unfolded.