Tatooine-like Planets are Real, and May Have Interesting History with Their Twin Suns
by Lenny Pierce on February 11, 2014
OK, not everything about planets like Kepler-16b and Kepler-34b is similar to Tatooine. Jabba owns no property there and we have no reason to think womp rats are native to any of them – sorry T-16 owners. But there is one element of these planets that is perfectly reminiscent of the sandy Star Wars planet, and that is their twin suns.
Our immediate concept of a solar system is usually a handful of planets orbiting around a single sun-like star. However, the majority of solar systems actually consist of two suns orbiting around one another, with planets orbiting around said pair called “circumbinaries”. These dual-sun systems are called “binaries,” but two stars is not even the limit. There are plenty of three star systems, and some systems have been observed with as many as seven stars.
Kepler-34b is a gas giant parked 4,900 light years from earth. Planets like Kepler-34b that orbit around binary stars are called circumbinaries. (David A. Aguilar)
When Luke’s moment of rumination before the double sunset of Tatooine was first shown in theaters, astronomers thought such a phenomenon was limited to science fiction. It was not until 2011 that NASA’s Kepler telescope discovered Kepler-16b orbiting two suns a mere 200 light years away. Even with two suns, Kepler-16b is far too cold to be habitable and is surrounded by thick atmosphere of gas. Not necessarily bad news, as this means that sarlacc pits remain the stuff of fantasy.
This image produced by Space.com shows the specific orbit of Kepler-16b around its suns. (Karl Tate / Space.com)
The origin of circumbinaries is a bit puzzling to researchers. Because all planets originally form from “protoplanetary disks” of gas and dust that orbit stars, scientists expected the extra-strong pull of two central stars to interfere with these disks’ ability to congeal into denser planets. To figure out how circumbinaries are able to form amidst these gravitational conditions, scientists have analyzed Kepler-34b. Running a simulation of a planetary formation, they found that it was only in the outermost sections of binary systems that planets could actually form. When applying this data to Kepler-34b, they realized that there is no way it could have formed as close to its suns as it is at present day. One theory is that circumbinaries form far away from their stars and eventually migrate to closer positions.
Will we ever find a circumbinary within a system’s habitable zone? Will we ever encounter a more earth-like circumbinaries instead of gas giants like Kepler-16b and Kepler-34b? Speculate below. I may not get to read your comments right away, as I am headed out to Tosche Station to pick up some power converters.