A recently discovered type of cold, lightweight star follows some wild orbits around the Milky Way, a team of astronomers have found.
Some of these so-called "ultracool subdwarfs" plunge almost through the center of the Milky Way, while others venture so far beyond the galaxy that they might be visitors from another galaxy, astronomers said here this week at the 214th meeting of the American Astronomical Society.
Ultracool subdwarfs were first recognized as a unique class of stars in 2003. They are distinguished by their low temperatures and low concentrations of elements other than hydrogen and helium.
They are at the bottom end of the size range of stars, with some being so small that they are closer to objects called brown dwarfs. They are up to 10,000 times fainter than the sun and are extremely rare — only a few dozen ultracool subdwarfs are known today.
These small stars also move surprisingly swiftly through the galaxy.
One of these subdwarfs, a star dubbed 2MAS 1227-0447 in the constellation Virgo, has an orbit that is so far out that it suggests it has an extragalactic origin.
Our calculations show that this subdwarf travels up to 200,000 light years away from the center of the galaxy, almost 10 times farther than the sun," said team member John Bochanski, also of MIT. In fact, it's further even than the Milky Way's nearest galactic neighbors.
"Based on the size of its one billion-year orbit and direction of motion, we speculate that 2MAS 1227-0447 might have come from another, smaller galaxy that at some point got too close to the Milky Way and was ripped apart by gravitational forces," Bochanski said.
http://www.space.com/scienceastronomy/0 ... warfs.html
Some of these so-called "ultracool subdwarfs" plunge almost through the center of the Milky Way, while others venture so far beyond the galaxy that they might be visitors from another galaxy, astronomers said here this week at the 214th meeting of the American Astronomical Society.
Ultracool subdwarfs were first recognized as a unique class of stars in 2003. They are distinguished by their low temperatures and low concentrations of elements other than hydrogen and helium.
They are at the bottom end of the size range of stars, with some being so small that they are closer to objects called brown dwarfs. They are up to 10,000 times fainter than the sun and are extremely rare — only a few dozen ultracool subdwarfs are known today.
These small stars also move surprisingly swiftly through the galaxy.
One of these subdwarfs, a star dubbed 2MAS 1227-0447 in the constellation Virgo, has an orbit that is so far out that it suggests it has an extragalactic origin.
Our calculations show that this subdwarf travels up to 200,000 light years away from the center of the galaxy, almost 10 times farther than the sun," said team member John Bochanski, also of MIT. In fact, it's further even than the Milky Way's nearest galactic neighbors.
"Based on the size of its one billion-year orbit and direction of motion, we speculate that 2MAS 1227-0447 might have come from another, smaller galaxy that at some point got too close to the Milky Way and was ripped apart by gravitational forces," Bochanski said.
http://www.space.com/scienceastronomy/0 ... warfs.html
Facebook
Twitter
Instagram