New Super Jupiter has triple sunsets and a super-long year

TUCSON, July 7 (UPI) -- If you lived on HD 131399Ab, you'd enjoy either constant daylight or three sunrises and sunsets, depending on the season, but you'd never live long enough to witness an entire season, let alone an entire orbit around your star.

The newly discovered exoplanet boasts seasons lasting 140 Earth years. One rotation around its host star takes 550 Earth years.

The alien world was discovered by a graduate student at the University of Arizona. The exoplanet's peculiarities are detailed in a new paper, published this week in the journal Science.

It's not the first Super Jupiter to be discovered -- it's roughly four times the size of Jupiter. Nor is it the first exoplanet found within in a three-star system. It is, however, the first discovered in a wide-orbit system, and its position is quite unexpected.

In fact, researchers can't be certain HD 131399Ab will remain in its current orbit for much longer.

"We can't say with certainty that the system is in fact stable and won't eject the planet in the near future," Arizona grad student Kevin Wagner, the discoverer, said in a news release.

But astronomers are excited to study it while they can.

"HD 131399Ab is one of the few exoplanets that have been directly imaged, and it's the first one in such an interesting dynamical configuration," explained Daniel Apai, an assistant professor of astronomy and planetary sciences at Arizona.

Remarkably, HD 131399Ab has remained in its current orbital position for 16 million years. Each rotation swings the planet 7.6 billion miles from its host star. Its unusually wide orbit brings it dangerously close to its sun's two stellar companions, which spin around each other as they orbit the central star.

The gravitational tug-of-war among the three stars may eventually eject HD 131399Ab into interstellar space.

For now, however, researchers will continue to study it. Unlike most exoplanets, researchers can study the alien world directly. So far, astronomers have determined that it hosts an atmosphere of predominantly hydrogen and helium, with a little bit of water and methane.

"This planet seems to be clear, or only partly cloudy at most," Wagner told National Geographic. "At even lower layers, the temperature will be yet hotter, and iron droplets may condense out of the hot atmosphere, forming iron rain."