Astronomers Explain Tatooine-like Planet Formation

| 19 Jun 2012 22:30

Exoplanets orbiting binary stars are real, but they keep their distance.

While it's not quite as fanciful as something like Doctor Who, Star Wars is hardly a source of verifiable, implementable scientific ideas. Sure, hyperspace may be physically feasible and some of the aliens are more believable than others, but cinematic abstractions like the Force are mostly just there for show. This is not the case with Tatooine's iconic twin sunset, which is a phenomenon that actually happens. Until now, researchers have puzzled over the idea of planets orbiting two suns. How did they form under such intense gravitational pull? A new theory suggests that the very gas clouds that birth these bodies are responsible for keeping them far away from the twin stars that would tear them apart.

At present, scientists are aware of at least three exoplanets (planets outside of our own solar system) that orbit binary stars: Kepler 16b, 34b and 35b. That these planets exist at all is somewhat remarkable, given the enormous gravitational pressure that two stars would exert. It seems impossible that stellar debris could amalgamate into planetary bodies with two stars pulling at it, but as is often the case in the far reaches of the universe, physics finds a way. Scientists theorize that planets in binary star systems form very far away from the stars in gas clouds, and the natural viscosity of the gas keeps planetary fragments together until they become self-sustaining spheres. This phenomenon is known as "gas drag."

Over the course of millions of years, these planets edge closer and closer to the binary stars, then form stable orbits. In fact, Kepler 16b stabilized about as close to a binary star system as scientists believe is possible. It rests just at the edge of the habitable zone, a term coined by astronomers to describe the most likely distance from a solar system's star (or stars) to support life. While this life would have to be able to withstand daily temperatures of approximately -70°C on a theoretical rocky moon, it's entirely possible that someone, somewhere is watching twin suns rise right now, just like Luke Skywalker did.

While this theory is by no means the last word on exoplanet formation in binary star systems, it contains a solid hypothesis that merits further testing. All we need is a space program capable of transporting some brave researchers a mere 200 light-years away. Sure, it may be nothing more than a cold ball of dirt, but it may also be home to an idealistic young farm boy with a laser sword, and that always ends well.

Source: Technology Review

Image: Wikipedia

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