Planets and stars hurtling out of our galaxy much faster than speeding bullet
London, Mar 30 (ANI): Researchers have shed light on some of the fastest moving objects in the cosmos.
When stars and their orbiting plants wander too close to the supermassive black hole at the centre of the Milky Way, their encounter with the black hole's gravitational force can either capture them or eject them from the galaxy, like a slingshot, at millions of miles per hour.
Although their origin remains a mystery and although they are invisible, black holes found at galaxy centres make their presence known through the effects they have on their celestial surroundings.
The Milky Way's black hole, a monster with a mass four million times that of the Sun, feeds on some of its neighbours and thrusts others out into the intergalactic void.
It's the expelled objects that "become hypervelocity planets and stars," said Idan Ginsburg, a graduate student in Dartmouth's Department of Physics and Astronomy.
"What we learn from these high-speed travelers has significance for our understanding of planetary formation and evolution near the central black hole."
Ginsburg, along with his doctoral adviser Professor Gary Wegner, and Harvard Professor Abraham Loeb, describe in the paper how they constructed computer simulations of these hypervelocity bodies as a means to understanding the dynamics involved.
"The paper is a 'call to arms' for other astronomers to join the search," Ginsburg said.
For the origin of hypervelocity bodies, Ginsburg and his colleagues point to the close interaction of a binary star system-two stars orbiting a common centre-with a massive black hole.
The likely scenario is the black hole draws one of the pair into its gravitational well while simultaneously ejecting the other at 1.5 million miles per hour. More than 20 of these hypervelocity stars have been identified in the Milky Way.
"You can also have a lone hypervelocity planet, peeled away from its star and ejected from the black hole. The same mechanism that produces a hypervelocity star produces a hypervelocity planet," Ginsburg explained.
"But because it is so small and traveling up to 30 million miles per hour, it cannot be seen. That doesn't mean they won't eventually be found, but currently it is beyond the limitations of our technology," Ginsburg added.
Ginsburg contends, however, that you could see a hypervelocity star ejected with planets still in tow. In this case, you might be able to see the planets as they cross in front of the star like an eclipse, appearing as a dip in its light curve. While the paper discusses the lone hypervelocity planets, it also draws attention to the planets rotating around the hypervelocity stars.
The study has been published in the Monthly Notices of the Royal Astronomical Society. (ANI)
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