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The star, known as US 708, is traveling at about 746 miles
(1,200 km) per second, fast enough to actually leave the Milky
Way galaxy in about 25 million years, said astronomer Stephan
Geier with Germany-based European Southern Observatory, which
operates three telescopes in Chile.
"At that speed you could travel from Earth to the moon in five
minutes," noted University of Hawaii astronomer Eugene Magnier.
US 708 is not the first star astronomers have found that is
moving fast enough to escape the galaxy, but it is the only one
so far that appears to have been slingshot in a supernova
explosion.
The 20 other stars discovered so far that are heading out of the
galaxy likely got their impetus from coming too close to the
supermassive black hole that lives at the center of the Milky
Way, scientists report in an article in this week’s edition of
the journal Science.
Before it was sent streaming across the galaxy, US 708 was once
a cool giant star, but it was stripped of nearly all of its
hydrogen by a closely orbiting partner. Scientists suspect it
was this feeding that triggered the partner’s detonation.
If confirmed, these types of ejected stars may provide more
insight into how supernova explosions occur. Since the
explosions give off a fairly standard amount of radiation,
scientists can calculate their distances by measuring how bright
or dim they appear and determine how fast the universe is
expanding.
(Editing by Cynthia Osterman)
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