Pavel KROUPA
AIfA Bonn, Allemagne
The pairing properties of stars and brown dwarfs are used to correct the observed object counts in a number of young populations. Because brown dwarfs are rarely companions to stars, but star–star binaries are very abundant, the IMF corrected for unseen companions shows a gap near 0.1Msun. This shows that the majority of brown dwarfs are a population that needs to be added separately to the stellar population. The origin of this separate brown dwarf population is discussed. Further, recently uncovered evidence for a top-heavy IMF in massive globular clusters and ultra compact dwarf galaxies will be shown.