In fact, the planet is so far removed from its sun's neighborhood that researchers thought it might have formed more like a companion star than an orbiting planet — having condensed from its own cloud of gas and dust instead of from the building blocks that swirled around the distant star.
"That was an open question for almost a year," study author Paul Kalas, an adjunct professor of astronomy at the University of California at Berkeley, said during an online news conference on Monday. "Now we sort of have an answer to what may have happened here."
Images from the Gemini Planet Imager (GPI) in the Chilean Andes and the Hubble Space Telescope revealed a lopsided comet system orbiting the star, which Kalas and his co-author Abhi Rajan of Arizona State University believe is an indication of a recent, violent disturbance in the solar system. This could mean that the planet formed close to the sun, as is more typical, and was then booted far away.
"The planet is misaligned with the plane of the comet system, so we think the whole system has recently been disturbed by some violent gravitational interaction, though we’re not sure exactly what happened," Kalas explained. "Something recently happened that kicked it out."
Something similar happened in our own solar system back in the day: Scientists believe that our system once had more than its current eight planets — until Jupiter strong-armed them out. It's possible a massive planet is what gave HD 106906 b the boot, but a passing star might be the culprit, too. In any case, the solar system is young — just 13 million years old, compared with our own 4.5-billion-year-old neighborhood. Watching the way it evolves after this violent encounter could help astronomers learn something about our own past.