"Nomad" Planets More Common Than Thought, May Orbit Black Holes

Stars and even black holes likely harbor "rogue," or "nomad," planets that were kicked out of the star systems where they were born, new simulations suggest. At the same time, a separate study suggests nomad planets are much more common than thought.
Astronomers used to shrug off notions of rogue planets, also called free-floating planets. Yet in the past few years, indirect observations of these galactic wanderers—combined with detailed supercomputer simulations—have suggested they do exist.
A study released Thursday, for instance, hints rogue planets might outnumber the Milky Way's 200 to 400 billion stars by a mind-boggling 100,000 to 1. Scientists previously thought there were only about two drifter planets for every star.
But what was still poorly understood was whether stars, black holes, and even other planets can capture such free-floating planets.
To find out, two astrophysicists simulated the evolution of several sizes and densities of star clusters. Eventually such clusters would dissipate as a galaxy's gravity pulled them apart.
The simulations suggested that between 3 and 6 percent of stars host rogue planets—a much higher number than thought.

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