A lone planet-size object (called SIMP J01365663+0933473) has been observed about 20 light years away. It is thought to be a “brown dwarf” – that is an object which is not quite large enough to attain the density needed to start hydrogen fusion and become a star. Scientists estimate the critical size between failed-star and ordinary star at about 13 times the mass of Jupiter. And the mass of this object is – yes – 12.7 times the mass of Jupiter – so it only just failed! It is said to be relatively young – about 200 million years old, and on its own – not orbiting a star.
But the most interesting property of the object is that it has an extremely strong magnetic field – more than 200 times as strong as Jupiter’s, which causes it to have strong auroras. The mechanism generating its magnetic field is unknown. Earth has auroras due to the interaction between the solar wind and Earth’s magnetic field. This object has no solar wind to interact with, so the mechanism may depend on an orbiting object. (Jupiter and its moon Io have a similar interaction.)