JHK photometry of brown dwarfs in Orion

Only 33 of the brown dwarf candidates are planetary mass candidates with estimated masses in the range 0.003<M<0.012M_{sun}_. In an extinction-limited sample (AV<5) complete to approximately 0.005M_{sun}_ (5M_Jup_) the mass function appears to drop by a factor of 2 at the deuterium burning threshold, i.e. at planetary masses.

After allowing for background contamination it is likely that planetary mass objects at 3-13M_Jup_ number <10% of the cluster population, with an upper limit of 13%. Analysis of the spatial distribution of stars and brown dwarf candidates suggests that brown dwarfs and very low-mass stars (M<0.1M_{sun}_) are less likely than more massive stars to have wide (>150AU) binary companions.