The theory offers an explanation for the handful of free-roaming planets found so far, and it could mean many more such rogue worlds exist across the Milky Way.

"Because every star dies, and many of these stars are massive enough to trigger planetary ejection, there is ample opportunity throughout the galaxy for stellar deaths to contribute to the free-floating population," said study leader Dimitri Veras, an astronomer with the U.K.'s University of Cambridge.

"We don't know yet how common these planets are, but the observational evidence suggests that there could be more planets floating in between stars than orbiting them," he added.

(Related: "Alien Planets Outnumber Stars, Study Says.")

The new model also hints that—in very rare cases—some survivor planets may