Wed Jul 2, 5:27 PM ET |
Reckless pulsars -- spinning searchlights in space -- might tear themselves apart if they whirled too fast, but ripples in the cosmic fabric first predicted by Albert Einstein may set a celestial speed limit. That limit is still extremely high, about 760 revolutions per second, astronomers said on July 2, 2003. But scientists figure some of the fastest pulsars could technically go two or three times that speed. Image is a still from a supernova animation of 'Birth of a Pulsar.' (NASA (news - web sites)/Reuters) |
I wish I understood half of it.
Thanks for the post.
Is this what passes for hard science nowadays? This is a load of pseudoscientific mumbo-jumbo. They say "watching" as if to imply the science is harder that it is. It implies someone peering through a telescope. "Detecting" would be a better verb. "Thermonuclear explosions on their surfaces"? The pulsars are thermonuclear reactions themselves. "The blasts last only a few seconds"? But the "flicker" is detected at 600 or so times a second? What correlation is there to the detected pulse and a determination that it is the rotation?
"As the gravitational wave comes to me or my instrument, it actually has the effect of stretching space a little bit in one direction and squashing it in another direction," Barish said. "It goes back and forth between stretching and squashing at the rate of several hundred times a second."
So where's the observational data for that? This guy's been watching too many Star Trek shows.
I don't want to live anymore.
Science - AP |
Study: Cosmic Brake Slows Spin of Pulsars By PAUL RECER, AP Science WriterWASHINGTON - Pulsars are the fastest spinning stars in the universe rotating at hundreds of revolutions per second and they could go twice as fast before flying apart. A new study by NASA (news - web sites) suggests that these exotic stars are held together by gravitational radiation that puts on the brakes.
Observations by NASA's Rossi X-ray Timing Explorer of 11 pulsars found that there seems to be a natural limit on how fast the strange stars can spin, astronomers said Wednesday at a news conference.
"The fastest-spinning pulsars could technically go twice as fast, but something stops them before they break apart," said Deepto Chakrabarty, a Massachusetts Institute of Technology (news - web sites) astronomer and the lead author of a study appearing in the journal Nature.
Chakrabarty called the natural brake "a cosmic speed limit" and said it may be the result of rotational energy being emitted from the stars as gravitational waves.
Pulsars are the remnants stars that were once eight to 20 times bigger than the sun. When their fuel was exhausted, the stars exploded and then collapsed into a very dense body equal to about 1.5 solar masses, but measuring only about 10 miles across.
The collapse starts the pulsar spinning at about 30 turns a second.
If there is a nearby star, the pulsar, with its superior density, will begin pulling material from its stellar companion. As this material spirals into the pulsar, the spin of the star rapidly increases.
In theory, said Chakrabarty, the star could spin up to 3,000 revolutions per second and eventually fly apart.
But in the study, Chakrabarty said the researchers found that the maximum speed for the 11 pulsars analyzed was below 760 revolutions per second, a velocity that approaches about 20 percent of the speed of light.
Pulsars give off beams of energy, such as X-rays, from fixed points on their surface. Since the objects are rapidly spinning, the beams appear to rapidly blink on and off, or pulse. By measuring these pulses, astronomers can estimate the rate of spin.
Chakrabarty said that Lars Bildsten, a University of California, Santa Barbara, astrophysicists, had theorized that the spinning speed of pulsars would be limited because irregularities on the star's surface would allow rotational energy to stream away as gravitational waves.
Bildsten, who took part in a NASA news conference, said the observation by Chakrabarty and others was unusual because it actually supported with observations an astrophysical theory.
"We're usually proven wrong," Bildsten, "so this is kind of exciting."
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On the Net:
Pulsar study: http://www.gsfc.nasa.gov/topstory/2003/0702pulsarspeed.html
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Some of the more rudimentary mechanics I can understand, but the theoretical/mathematical aspects remind me that I have all the quirks of a tortured genius, without the genius.
1 second = 760 pulsecs
Maybe Han Solo meant to say 'pulsec' instead of 'parsec.'