MessageToEagle.com - It's a very important discovery!
For the first time, an international team of scientists have detected all phases of thermonuclear burning in a
neutron star, located close to the center of the galaxy in the globular cluster Terzan 5.
Many models have been developed to predict how a neutron star should burst; models have predicted that at the
highest mass-accretion rates, plasma falls at such a high rate that thermonuclear fusion is stable, and occurs
continuously, without giant explosions.
Unfortunately, in the last several decades, all X-ray observations from nearly 100 exploding neutron stars have failed.
Thermonuclear bursts arise as gas moving at close to the speed of light crashes onto the neutron star surface. Image Credit: NASA
"Since the late 1970s, we mostly saw bursts at low mass-accretion rates, and few or no bursts at all at high mass-accretion
rates," Manuel Linares, a postdoc at MIT's Kavli Institute for Astrophysics and Space Research says.
In 2010, the Rossi X-ray Timing Explorer (RXTE) satellite detected large X-ray spikes from a binary star system in Terzan 5.
The RXTE observes the fast-moving, high-energy worlds of black holes, neutron stars, X-ray pulsars and bursts of X-rays
that light up the sky and then disappear forever.
Linares and his colleagues from MIT, McGill University, the University of Minnesota and the University of Amsterdam
analyzed data received by the RXTE and found the system's neutron star indeed exhibited X-ray patterns consistent
with low mass-accretion rates, in which plasma fell to the surface slowly.
While most neutron stars rotate a dizzying 200 to 600 times per second, this new star rotated much more slowly, at 11 rotations per second.
The team discovered evidence for higher mass-accretion rates, where more plasma falls more frequently, but found smaller
spikes, spaced closer together.
"We saw exactly the evolution that theory predicts, for the first time," says Deepto Chakrabarty, professor of physics
at MIT, and a member of the research team. "But the question is, why didn't we see that before?"
It's still unclear exactly how rotation affects thermonuclear burning.
The globular cluster Terzan 5. Image Credits: F.R. Ferraro, University of Bologna
"That's something that we need to look into," Linares says. "And now models will have to incorporate rotation, and
will have to explain exactly how that physics works."
According to Coleman Miller, professor of astronomy at the University of Maryland, designing models with rotation
in mind is an incredibly data-intensive feat, since thermonuclear fusion often occurs incredibly quickly, in tiny pockets
of a neutron star.
"If you're going to fully model out a burst, you have to resolve microseconds and centimeters," says Miller, who did not
take part in the research.
"No computer has been designed to do this. So these are interesting, likely suggestions, but it is going to be profoundly
difficult to confirm in a definitive way."
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The star's existence raised at once many questions for scientists.
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It will in fact be entirely different from what it is today.
One trillion years from now, an alien astronomer in our galaxy will have great difficulties figuring out how the universe began.
The Milky Way will have merged with the Andromeda galaxy to form the Milkomeda galaxy. Many of its stars, including our Sun, will have burned out.
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It is a spiral galaxy lying in the Dragon constellation,
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