BBC NEWS Science/Nature Strange 'twin' new worlds found: "A pair of strange new worlds that blur the boundaries between planets and stars have been discovered beyond our Solar System.
A few dozen such objects have been identified in recent years but this is the first set of 'twins'.
Dubbed 'planemos', they circle each other rather than orbiting a star.
Their existence challenges current theories about the formation of planets and stars, astronomers report in the journal Science.
'This is a truly remarkable pair of twins - each having only about 1% the mass of our Sun,' said Ray Jayawardhana of the University of Toronto, co-author of the Science paper.
'Its mere existence is a surprise, and its origin and fate a bit of a mystery.' "