Black hole ate my twin, but it can’t catch me November 10, 2005Posted by jtintle in Deep Space, European Southern Observatory (ESO), HE 0437-5439, Space News, Very Large Telescope.
NewScientist.com news service
A young star has been caught in the act of speeding out of the galaxy – seemingly on the run from a giant black hole that had already swallowed its twin.
Astronomers used the UVES spectrograph on the Very Large Telescope in Chile to spot the young runaway, called HE 0437-5439, in the dark outer reaches of the Milky Way.
The star appears to be 30 million years old and about eight times the mass of the Sun. It drew notice in part because it was found in a vast enclave of ancient stars – most of them billions of years old – that surrounds the disc of the galaxy like a bubble.
“This is a rather unusual place for such a star,” says team member Ralf Napiwotzki of the University of Hertfordshire, UK. “Massive stars are ordinarily found in the disc of the Milky Way.”
But the star’s speed truly set it apart from its sedate neighbours. It was clocked at 723 kilometres per second – fast enough that it will eventually escape the galaxy entirely. Such a high speed is quite unusual, says Shami Chatterjee, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US, who was not part of the team.
He says most other speedsters are neutron stars that have been kicked to high velocities after exploding in a supernova. “This star was not born in a supernova explosion, so it is really surprising to find an ordinary star that is going this fast,” he told New Scientist.