An exoplanet that orbits around two stars, known as a circumbinary planet, has recently been discovered by astronomers using the Kepler space telescope. The planet dubbed Kepler-16b has been compared to the planet Tatooine from Star Wars, due to the fact that it has two Suns in its sky.
Unfortunately the planet is uninhabitable because it is a gas giant approximately the size of Saturn orbiting way beyond the habitable zone (also known as Goldilocks zone). It has a nearly circular 229-day orbit around its two parent stars. This is similar to the distance of Venus from our Sun. However because of the fact that the two stars are much dimmer and cooler than our Sun, the planet is cold. The larger of the two stars is about 69 percent of the mass of our Sun, while the smaller is only 20 percent.
Unlike Saturn, Kepler-16b is nearly 50 percent denser, suggesting it is richer in heavy elements. This means that the planet has a large solid core, but at least half of it’s mass is made up of gas, so it is still a gas giant.
The Kepler-16 system is located about 200 light-years away from Earth.
This discovery proves that planets can form in binary star systems. Since most stars have at least one stellar companion, this brings up the number of planets left to discover in our stellar neighborhood. With more planets, the odds of discovering a habitable planet are now much higher.
Images Credit: NASA/JPL-Caltech/T. Pyle