Thursday, October 13, 2005 Posted: 1733 GMT (0133 HKT)
A surplus of massive stars has formed from a large disk of gas around the Milky Way's black hole.
WASHINGTON (Reuters) -- Dozens of massive stars, destined for a short but brilliant life, were born less than a light-year away from the Milky Way's central black hole, one of the most hostile environments in our galaxy, astronomers reported on Thursday.
On Earth, this might be a bit like setting up a maternity ward on the side of an active volcano. But researchers using the Chandra X-ray Observatory and other instruments believe there is a safe zone around black holes, a big dust ring where stars can form.
Black holes, including the one at the center of our galaxy, are monstrous matter-sucking drains in space, with gravitational pull so strong that nothing, not even light, can escape once it comes within the hole's grasp.
These young stars, however, are just far enough away to be held in orbit around the hole much as planets are kept in orbit around the sun, according to Sergei Nayakshin of the University of Leicester, United Kingdom.
At less than a light-year's distance, the 50 or 100 massive young stars are quite close to the black hole, but not close enough to be drawn in, Nayakshin said in a telephone interview.
A light-year is about 6 trillion miles, the distance light travels in a year. By comparison, Earth is about 26,000 light-years from the galactic center where the black hole lies.
Live fast, die young
The dusty zone in which these big stars thrive makes them impossible to see with optical telescopes, but the orbiting Chandra detected them by the X-rays they emit. Some smaller stars were also detected.
The massive stars buried in the cosmic murk are each between 30 and 50 times the mass of the sun, Nayakshin said.
The more massive the star, the brighter it shines, so that a star with 50 solar masses would be five orders of magnitude brighter than the sun; it would shine with the brilliance of 100,000 suns, Nayakshin said.
Over the course of perhaps 5 million years or so -- a mere blink of an eye in astronomical time -- these high mass stars would likely lose 80 percent of their mass and explode as supernovae, transforming into smaller black holes around the supermassive black hole in the center of our galaxy.
Unlike the sun, which burns its fuel slowly, these massive stars live fast and die young.
"These stars live a short life because they're so luminous, they just use up all of their energy too quickly," Nayakshin said. He is co-author of a study to be published in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.
These findings also contradict theorists who believe massive stars form elsewhere in the galaxy and migrate toward the black hole, he said. And this research may shed some light on how such big, rare stars are created.