Young brown dwarfs and planetary mass objects in open clusters
E. Moraux, J. Bouvier

Abstract: The discovery of hundreds of exoplanets and isolated brown dwarfs have led to new theories of star and planet formation that are now able to predict the initial mass function (IMF). Its shape is expected to be lognormal, with a peak around the local Jeans mass (a fraction of solar mass) and a lower limit around 3-8 Jupiter masses. Another important prediction is that the substellar part of the IMF is expected to strongly vary in different environments, while the higher, mass part should be invariant., , In this contribution, I will briefly review the results that we obtained from a CFH12K and MEGACAM large program (02B-04B) concerning the first 2 issues: IMF's shape and peak mass. We were able to detect all brown dwarfs (BD) down to 30 MJup in a variety of star forming regions (SFRs) and young open clusters (YOCs) with an age ranging between 1 and 600 Myr, and reliably derive the IMF from 30 MJup to the most massive stars in these regions., , The new observational frontier is the detection of very low mass brown dwarfs and isolated planetary mass objects (IPMOs), with a mass less than 30 MJup and down to the predicted lower limit of the IMF. Only deep infrared surveys can reveal these ultracool substellar objects. I will present a WIRCam large program (07A-08B) that we are now conducting to detect substellar objects and IPMOs with masses between 1 and 30 MJup in a sample of 7 young clusters. I shall present, preliminary results that we obtained in the Rho-Oph region.