Planets with no host stars wouldn’t be very hospitable, but life might still find a way to hang in.
A “rogue” exoplanet with the preliminary name PSO J318.5-22 has been detected by a group of astronomers led by Michael Liu from the University of Hawaii at Manoa. By “rogue planet,” astronomers mean one that has no host star – it wanders alone through galactic space.
This particular world is a Jupiter-type gas giant, located about 80 light years from Earth in a collection of young (less than 50 million years old) stars in the Beta Pictoris moving group. With only about six times the mass of Jupiter, PSO J318.5-22 is one of the least massive rogue planets detected so far. It’s a sub-brown dwarf, even less massive than a brown dwarf (a gas giant that failed to become a star).
Radiation levels within this type of planet are very high, with a seamless transition from gas to liquid in the deep atmosphere. Convection would move any organic compounds at the surface down into the interior, where they would encounter extreme temperatures and pressures. Thus, life within a gas giant like PSO J318.5-22 has to be considered extremely unlikely. But the ...