The Kepler space telescope continues to find transiting exoplanets throughout our galaxy. This time it has been used to find a planet orbiting two stars similar to that of ‘Tatooine’ from Star Wars. Kepler-453b is the tenth example of a planet orbiting a binary star system that Kepler has found.
A binary system is one where two stars are in orbit around a common centre of mass. On Tatooine, two stars can be seen in the sky; this is what the view might look like from Kepler-453b. Surveys of stars have revealed that systems where two or even more stars are orbiting around one another are quite common. It wasn’t known until recently was whether planets could form in these star systems. The first planet to be discovered orbiting a binary system by Kepler was discovered four years ago and since then nine more have been discovered.
Planets orbiting binary systems orbit around both stars rather than just one of the stars. The two stars in this system are of different sizes. One is very similar to our sun with a mass of 94% of it. The other is a lot smaller at only 20% of the mass of the sun. The two stars orbit each other in a time of 27 days.
Kepler-453b is in the habitable zone of this system. It orbits the two stars every 240 days. The planet itself is 6.2 times as large as Earth so it probably isn’t terrestrial. It’s likely it is a gas giant planet so the presence of life is ruled out.
While the planet itself isn’t habitable, that doesn’t mean we should give up the search for like in this system. The planet could harbor rocky moons, which may contain life. If you put Jupiter’s moon Europa around this planet, it would become a water world very favourable to life. The age of the system is estimated to be between 1 and 2 billion years old so it is relatively young. This is probably not enough time for complex life to evolve so any life on an exomoon is likely very simple and single cellular.
Kepler-453b is about 1400 light years away so observations of it and its moons are impossible with our current technology. No exomoons have been found to date.
William Welsh and his team say that they were very lucky to find this planet. The plane of orbit of the planet is constantly changing putting it in and out of transit relative to Earth. It can only be seen in transit about 9% of the time. This fact will make it very difficult to do follow up studies on the planet as the next time it will transit is in 2066.
The Kepler space telescope has been one of the most important missions NASA has put forth and although its primary mission ended in 2012, Kepler continues to find exciting new planets. There are still thousands of candidates Kepler has found awaiting confirmation.