These Rogue Worlds Upend the Theory of How Planets Form
“We know from direct imaging searches of young stars that very few stars have giant planets in [wide] orbits,” Bate said. “It is difficult to accept that there were many large planetary systems in Orion to disrupt.”
Rogue Objects Abound
At this point, many researchers suspect there’s more than one way to make these strange in-between objects. For instance, with some fiddling, theorists might find that supernova shock waves can compress smaller gas clouds and help them to collapse into pairs of tiny stars more readily than expected. And Wang’s simulations have shown that booting giant planets in pairs is, at least in some cases, theoretically unavoidable.
While many questions remain, the multitude of free-floating worlds discovered in the past two years has taught researchers two things. First, they form quickly—over millions of years, rather than billions. In Orion, gas clouds have collapsed and planets have formed, and some, perhaps, have even been dragged into the abyss by passing stars, all during the time in which modern humans were evolving on Earth.