Growing pains.
This artist's conception shows a neutron star known as a magnetar crackling with extremely powerful magnetic activity.
Credit: Gregg Dinderman/Sky & Telescope
Posted on 02/23/2008 9:05:41 PM PST by neverdem
Growing pains.
This artist's conception shows a neutron star known as a magnetar crackling with extremely powerful magnetic activity.
Credit: Gregg Dinderman/Sky & Telescope
"When you hear hoofbeats," the old saying goes, "think horse, not zebra." But what if your horse suddenly grows zebra stripes? That's the predicament astronomers faced when a star they were observing--a rapidly spinning remnant of a supernova called a pulsar--started emitting powerful bursts of x-rays considered the hallmark of a much-rarer object called a magnetar. The finding strongly suggests that pulsars, also known as neutron stars, and magnetars are linked and paves the way for a better understanding of stellar evolution.
Pulsars are the dense cores left over after stars of a certain mass explode into supernovae. Weighing as much or more than the sun but only as big as asteroids, they can rotate tens or even hundreds of times a second (versus once a day for Earth). Sky surveys have identified about 1800 pulsars within the Milky Way, most of which emit pulsing radio signals that rise and fall as the pulsars spin.
The stripe-changing pulsar, named PSR J1846-0258, lies about 20,000 light-years away in the constellation Aquila. A team of researchers from NASA and elsewhere was observing it using the Rossi X-ray Timing Explorer (RXTE) spacecraft when the star suddenly erupted in a blast of x-rays. The display, reported online today in Science, made PSR J1846-0258 a candidate for being a magnetar--a type of neutron star with an enormously powerful magnetic field. Magnetars, so rare that only a dozen or so have been discovered, routinely emit high-energy x-rays and even gamma rays. But no one had ever observed a pulsar emitting such bursts.
"The bursts were completely unexpected," says astrophysicist and lead author Fotis Gavriil of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Because PSR J1846-0258 is a very young pulsar (a mere 1000 years old) and because its magnetic field strength is considerably lower than those from bona fide magnetars, Gavriil says, the researchers suspect it is still evolving. He says the discovery raises important questions about the two types of stars: Do pulsars behave like magnetars only periodically and then revert? Did all magnetars originate as pulsars? "We really need to follow this source, and others like it, to answer these questions," he says.
Astrophysicist Duncan Lorimer of West Virginia University in Morgantown calls the discovery "fantastic." A decade ago, he says, very little was known about any connections between pulsars and magnetars. Now, Lorimer says, the evolutionary connections between the two are strengthening, and observations like this one will help "elucidate our understanding of what happens to a young neutron star after its birth in a supernova." And astrophysicist Robert Duncan of the University of Texas, Austin, calls the findings "fascinating and important," because they represent the first time that magnetically generated x-rays have been seen coming from a rotationally driven pulsar. Duncan, who developed the theoretical behavior of magnetars in 1992, says he is not so sure the object will turn out to be a magnetar, but "neutron stars are constantly surprising scientists, so future observations … will certainly be interesting."
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I love it when they are wrong. It should make them rethink the models but they usually just make fictitious things up as a response.
I’m genuinely curious.
You and kinoxi obviously have a deep-seated contempt for scientists (and even the process of science, perhaps.) Why? What drives it?
bmflr
Scientists Measure What It Takes to Push a Single Atom
FReepmail me if you want on or off my health and science ping list.
So, how high are the mountains on a black hole? 8<)
Well, as a frequent visitor and proponent of the Hanford LIGO facility, I am looking forward to seeing potential gravity wave data (and processing it via Einstein@Home).
That is way science works. You make an observation, especially an unexpected one. Then you postulate an explanation. From that explanation, you make a prediction. If your science is an experimental one, your prediction should the outcome of an experiment, but if, like astronomy/astrophysics, it's an observational one, they you have to make more observations to look for the effect you predict. If you find it, your explanation, ie. your theory, is verified, always subject to other observations tending to disprove it.
I’ve been feeling a little odd lately and now I know why:
http://img.photobucket.com/albums/v200/pisky/alienpixyhat.jpg
Must be my hat!
Oh. I didn’t realize that by setting out to prove one’s explanation of an anomalous explanation by observing its effects was proper scientific conduct. But I guess that properly shoulding the outcome of an experiment verifies a prediction such that it’s underlying explanation must be true, and the burden of proof is upon falsification (should they tend to do so).
IF the sun rotates, is it "exactly" in phase with the Earth? And does the sun's axis of rotation coincide with the axis of the Earth's orbit?
Cheers!
Kinda hard to fit an entire star into a test tube...
Cheers!
Here is great movie of the Crab Nebula pulsar using Hubble and Chandra satellite time-lapse pictures. Quite remarkable if you are in to this kind of thing.
http://chandra.harvard.edu/photo/2002/0052/combinedmovie.mpg
This artist's conception shows a neutron star known as a magnetar crackling with extremely powerful magnetic activityThanks neverdem.
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The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization
by Richard Firestone,
Allen West, and
Simon Warwick-Smith
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