Abstract
We present an overview of the latest results of an ongoing large-scale, optical photometric and spectroscopic survey of very low mass stars and brown dwarfs down to M ∼ 0.02 M_⊙ in the dispersed, off-cloud populations of the Orion OB1 star forming region. The survey is based on the combination of multi-epoch optical photometry in R and I bands obtained with the Quest-I camera at the Venezuela National Astronomical Observatory, with near-IR data from the VISTA and 2MASS surveys, spanning a total area of ∼200~deg^2. The photometric survey is being complemented with follow up optical spectroscopy on the Hectospec instrument on the 6.5 m MMT, which so far has provided spectroscopic confirmation of young brown dwarfs down to ∼0.05~M_⊙ over 6~deg^2. An overview of the results on the sample of stellar and substellar objects spectroscopically confirmed as members of Orion and those that still remain as photometric candidates are presented, focus on the initial mass function, the mass dependence of the spatial distribution, the near infrared excesses and the fraction of objects with Classical or Weak T Tauri-like characteristics. These results will be extended and discussed in terms of the predictions from brown dwarf formation models in Downes, J.J., et al. (2011, in preparation).
