An artistic rendering reveals a hypothetical sunset on HD 1885 Ab, a rocky world in a triple star system. The view from KELT-4Ab, a gas giant, would likely look similar. Photo by NASA/JPL-Caltech

BOSTON, April 1 (UPI) -- Astronomers have identified an alien planet in a three-star system.

Scientists have discovered thousands of exoplanets, many with two stars, but this is only the fourth found with three. And the latest is the closest of the four, approximately 685 light-years from Earth.


KELT-4Ab is a Jupiter-like gas giant. It only orbits one of the three stars, KELT-A. Its trip around the star takes three days.

The other two stars in the system are dimmer and farther away, orbiting around each other at a considerable distance. The spinning pair take 30 years to orbit about each other. As they do, they're also circling the system's primary star, KELT-A. A single trip around KELT-A takes 4,000 years.

Because KELT-4Ab is much closer to its star, it would appear up to 40 times larger than Earth's sun in the sky.

Most gas giants orbit their host star at a considerable distance. The close proximity of KELT-4Ab makes it a "hot Jupiter." Researchers continue to grapple with the origin of hot Jupiters, with various theories explaining how and why they make their journey from the outer solar system to the toastier confines of the inner solar system.

It's possible the nature of the multi-star system explains the intimate orbit of KELT-4Ab, but more research is necessary.

Researchers at the Harvard-Smithsonian Center for Astrophysics published their latest findings in the Astronomical Journal.