Astronomers find star speeding out of the galaxy

Astronomers have found a star hurtling
through the galaxy faster than any other, the
result of being blasted away by the explosion
of a massive partner star, researchers said on
Thursday.
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.