Seven years ago, astronomers boggled when they found the first runaway star flying out of our Galaxy at a speed of 1.5 million miles per hour. The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?
New research shows that the answer is yes. Not only do runaway planets exist, but some of them zoom through space at a few percent of the speed of light - up to 30 million miles per hour.
"These warp-speed planets would be some of the fastest objects in our Galaxy. If you lived on one of them, you'd be in for a wild ride from the center of the galaxy to the Universe at large," said astrophysicist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics.
"Other than subatomic particles, I don't know of anything leaving our galaxy as fast as these runaway planets," added lead author Idan Ginsburg of Dartmouth College.
Such speedy worlds, called hypervelocity planets, are produced in the same way as hypervelocity stars. A double-star system wanders too close to the supermassive black hole at the galactic center. Strong gravitational forces rip the stars from each other, sending one away at high speed while the other is captured into orbit around the black hole.
For this study, the researchers simulated what would happen if each star had a planet or two orbiting nearby. They found that the star ejected outward could carry its planets along for the ride. The second star, as it's captured by the black hole, could have its planets torn away and flung into the icy blackness of interstellar space at tremendous speeds.
A typical hypervelocity planet would slingshot outward at 7 to 10 million miles per hour. However, a small fraction of them could gain much higher speeds under ideal conditions.
Current instruments can't detect a lone hypervelocity planet since they are dim, distant, and very rare. However, astronomers could spot a planet orbiting a hypervelocity star by watching for the star to dim slightly when the planet crosses its face in a transit.
For a hypervelocity star to carry a planet with it, that planet would have to be in a tight orbit. Therefore, the chances of seeing a transit would be relatively high, around 50 percent.
"With one-in-two odds of seeing a transit, if a hypervelocity star had a planet, it makes a lot of sense to watch for them," said Ginsburg.
Eventually, such worlds will escape the Milky Way and travel through the intergalactic void.
"Travel agencies advertising journeys on hypervelocity planets might appeal to particularly adventurous individuals," added Loeb.
Harvard-Smithsonian Center for Astrophysics: http://cfa-www.harvard.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
NASA hopes Dawn mission can answer the big question: could life lurk in icy volcanoes on Ceres, the asteroid belt's biggest resident?
One twin will spend the year in space, the other on the ground. Monitoring their health could let us tease apart the effects of space flight from genetics
The Sierra Negra volcano in the central Mexican state of Puebla is the site of an ambitious astrophysical project which houses the largest gamma ray observatory ever built on the planet.
CAPE CANAVERAL, Fla (Reuters) - An unmanned Delta 4 rocket blasted off from Florida on Wednesday to deliver the ninth of 12 next-generation Global Positioning System satellites into orbit.
CAPE CANAVERAL, Fla (Reuters) - A NASA robot ship will pluck a large boulder off an asteroid and sling it around the moon, becoming an ad hoc destination to prepare for future human missions to Mars, the U.S. space agency said on Wednesday.
Scott Kelly and Mikhail Kornienko will spend a year together on the International Space Station and conduct research into the feasibility of a manned Mars mission
Jupiter may have ploughed through the early solar system, driving some of the first planets to a fiery death in the sun – and cleared room for planets like Earth
How did the Vikings find their way over the sea? Medieval artefacts are giving us important clues as to how they might have done it
New data clears up a case of mistaken stellar identity stretching back to the year 1670
But it wasn't exactly a fast race