‘Cosmic Cannonball’ discovered moving at 3 million miles per hourNovember 29th, 2007 - 4:00 pm ICT by admin
Washington, Nov 29: Astronomers have discovered one of the fastest moving (neutron) stars with NASA’s Chandra X-Ray Observatory.
Known as RX J0822-4300, this ‘cosmic cannonball’ was observed over a period of about five years, during which three Chandra observations clearly show it moving away from the center of the Puppis A supernova remnant.
This remnant is the stellar debris field created during the same explosion in which the neutron star was formed about 3700 years ago.
So-called hypervelocity stars have been previously discovered shooting out of the Milky Way with speeds around one million miles per hour. One key difference between RX J0822-4300 and these other reported galactic escapees is the source of their speed. The hypervelocity stars are thought to have been ejected by interactions with the supermassive black hole in the Galaxy’s center.
This neutron star, by contrast, was flung into motion by the supernova that created Puppis A. The data from the Chandra observations suggest that the explosion was lop-sided, kicking the neutron star in one direction and the debris from the explosion in the other.
By combining how far it has moved across the sky with its distance from Earth, astronomers determined the neutron star is moving at over 3 million miles per hour. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far.
“This star is moving at 3 million miles an hour, but it’s so far away that the apparent motion we see in five years is less than the height of the numerals in the date on a penny, seen from the length of a football field,” said Frank Winkler of Middlebury College in Vermont.
“Just after it was born, this neutron star got a one-way ticket out of the Galaxy,” said co-author Robert Petre of NASA’s Goddard Space Flight Center in Greenbelt, Md. “Astronomers have seen other stars being flung out of the Milky Way, but few as fast as this,” he added.
The breakneck speed of the Puppis A neutron star, plus an apparent lack of pulsations from it, is not easily explained by even the most sophisticated supernova explosion models.
“The puzzle about this cosmic cannonball is how nature can make such a powerful cannon,” said Winkler. “The high speed might be explained by an unusually energetic explosion, but the models are complicated and hard to apply to real explosions,” he added. (ANI)
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