Newly Discovered 16 Million Years Old Planet Has Three Stars

A first year doctoral student and other astronomers from the University of Arizona has discovered an exoplanet orbiting a tri-star system.

The new planet, dubbed as HD 131399Ab, was the first ever exoplanet to be discovered using the SPHERE instrument on the Very Large Telescope of ESA located in Chile. Due to the sensitivity of SPHERE to infrared, it can detect heat signatures of young planets. The SPHERE also have sophisticated features capable of correcting for atmospheric disturbances and blocking out the otherwise blinding light of their host stars.

According to the paper published in the journal Science, HD 131399Ab is located about 320 light-years from Earth in the constellation of Centaurus and is only about 16 million years old. The planet is estimated to have a mass of four Jupiter with a temperature of around 580 degrees Celsius.

The planet orbits the brightest star, called as HD 131399A, in the tri-star system. On the other hand, the two other stars, dubbed as HD 131399B and HD 131399C spins around each other while also orbiting HD 131399A. HD 131399A is estimated to have 80 percent more massive than the sun. HD 131399B has the same mass with HD131399A but only about 0.87 times as bright as the sun. Meanwhile, HD131399C is only about 0.17 as bright and about 60 percent of the mass of the sun.

"For about half of the planet's orbit, which lasts 550 Earth-years, three stars are visible in the sky; the fainter two are always much closer together, and change in apparent separation from the brightest star throughout the year," explained Kevin Wagner, lead author of the study, in a statement.

The researchers noted of the unique orbital structure of the tri-star system. The orbit of HD 131399Ab around the HD 131399A is considered to the widest orbit of a planet ever found in a multi-star system. Also, HD 131399B and HD 131399C orbits so close to HD 131399A, which is very different in other triple star system that have a planet orbiting the main star but is very far away from the two other stars.