According to Gizmodo, this planet with three suns shouldn’t even exist.
In 2014, the ESO’s Very Large Telescope was outfitted with a new instrument called SPHERE, which features an adaptive optics system for canceling out the distortion of Earth’s atmosphere, as well as an instrument to block starlight, called a coronagraph. SPHERE is now one of the most powerful direct imaging tools planet hunters have at their disposal, and it bagged an exotic triple-star exoplanet on its very first observational campaign.
HD 131399A orbits a young A-type star, HD 131399A, taking a casual 550 Earth years to complete a single rotation. Far beyond its orbit, a Sun-like star and a K-dwarf (predictably named B and C) twirl about one another like dumbbells, while also revolving slowly around star A.
“The planet is about a third of a way out [between star A, and the B/C pair],” Wagner said. “All of the stars have a lot of gravitational influence on the planet, meaning it has a very irregular orbit that’s constantly evolving and changing.”
Whether the competing gravitational tug of three stars will cause the planet to be ripped apart or ejected from its overcrowded birthplace remains to be seen. In cosmic terms, HD 131399Ab is an infant, just 16 million years old. But the fact that it has survived this long suggests there could be more worlds like it. Some could even be small, rocky, and habitable.
“We thought that [triple star planets] weren’t going to be common, or at least in this extreme configuration, so we hadn’t really looked,” Wagner said. Studying these systems will expand our understanding of the conditions under which planets form and migrate about.