Superfast stars racing through Milky Way found
New York: Astronomers have discovered six speedy stars, rocketing through space at up to 3.2 million kilometres per hour, which likely ejected from a giant black hole at the Milky Way's heart.
They represent the first known "hypervelocity stars" with masses similar to that of our Sun.
The discovery could shed light on how stars form in the dust-shrouded core of our home galaxy.
The galactic centre is cloaked in a halo of dust that obscures all but the brightest stars from astronomers' telescopes, Space.Com reported.
But hypervelocity stars could provide a window into the star formation going on at the Milky Way depths.
That's because hypervelocity stars are thought to form when the supermassive black hole at the centre of a galaxy devours one star in a binary system and ejects its twin, flinging it through space at superfast speeds, said study author Keith Hawkins, an astronomy student at Ohio University.
"These are incredibly fast-moving objects that are actually gravitationally unbound to the Milky Way," he said.
Though the stars may be close to the black hole, they are not shrouded by dust and can be detected with telescopes.
Since speedy rogue stars have been ejected from the galactic centre, identifying them can reveal the types of star formation occurring there.
But until now, astronomers searching for these hypervelocity stars looked for bright, blue stars in locations where they weren't supposed to form.
Those stars, while easier to find, are typically three to four times as massive as our own Sun, while most stars forming in other regions of the galaxy are the size of our Sun or smaller, Hawkins said.
Hawkins and Adam Kraus, an astronomer at the University of Hawaii, used data from the Palomar 5-metre telescope in California.
They found 130 stars on the edges of the Milky Way's central black hole that had travelled a remarkable distance. They then narrowed that group to stars travelling at extreme speeds consistent with ejection from the Milky Way's centre. Six stars met those criteria.
While the new results are intriguing, they need to be confirmed, Hawkins said.