One of the most iconic scenes ever filmed for Star Wars occurred when Luke walked outside his boyhood home on the rocky, desert planet of Tatooine and looked up at the two suns setting. Now, scientists believe that these Earth-like worlds with two suns in their sky may actually be more common than originally thought, throughout the Milky Way Galaxy.
A number of gaseous exoplanets have already been discovered in two-star systems, but many astronomers believed that habitable worlds couldn't take shape in an environment with the chaotic orbital dynamics caused by two stars. However, mathematical models suggest otherwise, according to a new study.
"It is just as easy to make an Earth-like planet around a binary star as it is [to do so] around a single star like our sun," study lead author Ben Bromley, of the University of Utah, said in a statement. "So we think that Tatooines may be common in the universe."
"Around a single star, planetesimals tend to follow circular paths - concentric rings that do not cross," Bromley says. "If planetesimals do approach each other, they can merge together gently."
"For over a decade, astrophysicists believed that planets like Earth could not form around most binary stars, at least not close enough to support life."
The simulations that predict that planets couldn't form in two star environments made the assumption that planets travel in circular orbits. But the modeling work performed by Bromley and his co-author Scott Kenyon, of the Smithsonian Astrophysical Observatory, shows that, in binary systems, rocky building blocks likely make their way into oval paths.
"If the planetesimals are in an oval-shaped orbit instead of a circle, their orbits can be nested, and they won't bash into each other," Bromley says. "They can find orbits where planets can form."
Bromley and Kenyon also examined seven exoplanets discovered by the Kepler space telescope, all of which are gaseous planets much like Jupiter. They believe that these planets likely formed in the outer areas of their systems where more gas and dust were available and then traveled into the habitable zones of their systems due to gravitational interactions with other planets.
The new study supports this theory but also suggest that the clouds of dust and gas could have formed the planets right where they are after moving inward.
In light of this new study there could come a day in human history when one of these planets is discovered and even explored, bring the galaxy far, far away much closer to home than anyone thought possible.
