Mysteries of distant solar systems will never cease to amaze us. When we still ponder over what lies beyond our very own Milky Way galaxy, astronomers have discovered a strange planet that would make Luke Skywalker's Tatooine look behind the times. Unlike Skywalker's home planet, which had two suns in the sky, the newly identified world orbits a three-star system.
Dubbed “HD 131399Ab,” the planet has been discovered by a team of astronomers led by the University of Arizona in Tucson, using direct imaging. The planet travels around its central sun in an orbit twice as large as Pluto’s, which makes it by far the widest known exoplanet with a multi-star system.
“For about half of the planet's orbit, which lasts 550 Earth-years, three stars are visible in the sky, the fainter two always much closer together, and changing in apparent separation from the brightest star throughout the year,” said Kevin Wagner, a first-year PhD student at the University of Arizona and the first author of the study, published in the journal Science Thursday.
Located about 340 light years from Earth, HD 131399Ab is believed to be nearly 16 million years old, making it one of the youngest exoplanets discovered to date. The planet, which is four times as massive as Jupiter, is also believed to be one of the coldest exoplanets with a temperature of about 1,070 degrees Fahrenheit or 580 degrees Celsius.
“For much of the planet's year the stars appear close together, giving it a familiar night-side and day-side with a unique triple-sunset and sunrise each day,” Wagner said, adding that at some point the planet has a near-constant daytime that lasts for about one-quarter of its orbit, or roughly 140 Earth-years.
According to the scientists, it is not clear where the planet formed and how it ended up on its wide orbit. However, they believed that “there is more variety out there than many would have deemed possible.”