'Star Wars'-Like Planets May Exist in the Universe
The image of Luke Skywalker staring at the twin sunsets of his homeplanet Tatooine captured the imagination of millions of movie watchers everywhere. But now astrophysicists are saying that this desert planet may not be just a thing of science fiction, but a reality.
According to a new study published in the Astrophysical Journal, Earth-like, solid planets such as Tatooine - which is part of a binary star system, explaining for the double sunset - likely exist and may be widespread across the Universe.
"Our main result is that outside a small region near a binary star, [either rocky or gas-giant] planet formation can proceed in much the same was as around a single star," the researchers wrote. "In our scenario, planets are as prevalent around binaries as around single stars."
"Tatooine sunsets may be common after all," the team added.
In the study, researchers Ben Bromley of the University of Utah, and Scott Kenyon of the Smithsonian Astrophysical Observatory, used complex mathematical formulas to describe how binary stars can be orbited by planetesimals - asteroid-sized rocks that clump together to form planets.
Until now, it was believed that planets like Earth could not form around most binary stars - at least, not close enough to support life. That's because planetismals have to merge together gently in order to grow. But around a single star, most planetismals follow a circular orbit in which their paths do not cross, making it difficult for them to merge.
And if planetismals orbit a pair of stars, usually their paths get so entangled that they collide at high speeds, destroying one other.
However, the researchers find that if planets start out in an oval-shaped - not circular - orbit, they won't smash into each other and will settle into orbits that foster planet formation.
"We took our sweet numerical time to show that the ride around a pair of stars can be just as smooth as around one," when it comes to the early steps of planet formation, Bromley said in a statement. "The 'made easy' part is really saying the same recipe that works around the Sun will work around Tatooine's host stars."
Bromley and Kenyon didn't conduct their simulations to the point of planet formation, but they did show that planetesimals could survive without collisions for tens of thousands of years in concentric, oval-shaped orbits around binary stars.
"We are saying you can set the stage to make these things," Bromley explained. "It is just as easy to make an Earthlike planet around a binary star as it is around a single star like our Sun. So we think that Tatooines may be common in the Universe."
In the hunt for alien life, NASA's Kepler space telescope has already discovered more than 1,000 planets orbiting other stars, including some rocky planets in the so-called habitable zone - the Goldilocks area that's just right for life. Even our own Milky Way harbors thousands of potentially habitable planets.
So far, Kepler has found seven planets orbiting within or near the habitable zone around binary stars, but all of them are gas giants.
"The planets that Kepler has discovered so far around binary stars are larger, Neptune- or Jupiter-sized gas giants," Bromley said. "None of those found so far are small and rocky like our Earth - or like Tatooine in 'Star Wars.'"
However, that doesn't mean scientists are giving up. They will continue the search for habitable planets like Tatooine, and hope that maybe the fantastical world of 'Stars Wars' one day will become a reality.
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