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Monday, April 9, 2012

Super-fast planets

Over the past few decades, cosmologists have theorized about and then confirmed the existence of ‘hypervelocity’ stars.  These are stars that zoom outward at up to 30 million miles per hour.  To put that in perspective, the sun circles the Milky Way at about 500,000 miles/hour and the space shuttle (RIP) could go up to 18,000 miles/hour. To date, at least sixteen such speedy stars have been identified.

During the same time span, hundreds of exoplanets have been discovered.  In fact, many astronomers now believe that nearly every star has at least one planet.  I think you can see where this is going. Idan Ginsburg, Abraham Loeb and Gary Wegner of Dartmouth College have proposed the existence of hypervelocity planets.

Both hypervelocity stars and planets may have the same origin: a binary star system that strays too close to a massive black hole. The two partner stars are ripped apart and one is sent careening out of the galaxy while the other is held hostage by the black hole’s gravitational forces. The escaping star would carry along any orbiting planets it might have, also at high velocity. Planets orbiting the captured star could be sheared off and thrown out of the galaxy as high-speed rogue planets.

Loeb suggests that these planets might not be without their uses, envisioning:
Travel agencies advertising journeys on hypervelocity planets [that] might appeal to particularly adventurous individuals.