6.11.2009

'Ultracool subdwarf' stars speeding through Milky Way

·A recently discovered family of peculiar wandering stars may include a visitor from another galaxy, scientists believe.
http://www.telegraph.co.uk/scienceandtechnology/science/space/5489268/Ultracool-subdwarf-stars-speeding-through-Milky-Way.html
http://www.stsci.edu/~inr/thisweek1/thisweek/m81b.gif
The stars, described as "ultracool subdwarfs" follow very unusual paths around our galaxy, the Milky Way.
They have low temperatures and are small enough to be close to planet-like objects.
Only a few dozen ultracool subdwarfs, which are up to 10,000 times fainter than the Sun, have been identified.
One of the oddest aspects of the stars is the rapid speed at which they travel. They have been clocked at more than a million miles per hour.
[...]
Astronomers found that the stars had bizarre orbits. Some plunged deep into the centre of the Milky Way on eccentric, comet-like tracks. Others made slow, swooping loops far beyond the Sun's orbit.
Unlike the majority of nearby stars, most ultracool subdwarfs spent a lot of time thousands of light years above or below the galactic disc.
At least one of the objects - a star designated 2MASS 1227-0447 in the constellation Virgo - has an orbit indicating that it might have originated in another galaxy.
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