No large population of unbound or wide-orbit Jupiter-mass planets

Understand

Gravitational microlensing is the only method capable of exploring the entire population of free-floating planets down to Mars-mass objects, because the microlensing signal does not depend on the brightness of the lensing object.

• A characteristic timescale of microlensing events depends on the mass of the lens: the less massive the lens, the shorter the microlensing event.
• A previous analysis of 474 microlensing events found an excess of very short events (1-2 days) - more than known stellar populations would suggest - indicating the existence of a large population of unbound or wide-orbit Jupiter-mass planets (reported to be almost twice as common as main-sequence stars).
• These results, however, do not match predictions of planet formation theories and are in conflict with surveys of young clusters.