Embedded Star Clusters: The ISO View
  We summarize the main results of a mid-IR photometric survey with ISO for a few nearby embedded clusters. The sensitivity and spatial resolution of ISOCAM provided a wonderful tool for studies of the youngest stellar clusters, which are still deeply embedded in their parent molecular clouds. Mid-IR photometry is found to be extremely efficient in finding all the young stellar objects (YSOs) with IR excesses, i.e. mainly T Tauri stars surrounded by circumstellar disks and also some Class I sources. The spatial distribution of these sources is highly clustered and even sub-clustered, with a tendency of stronger concentration for the younger regions. The improved samples of IR-excess YSOs appear complete down to 0.03 L_sun for the most nearby clusters. This gives constraints on the mass functions well into the brown dwarf domain. The first results show that the mass functions of these clusters are identical to the field star IMF derived by Kroupa et al. (1993) with a flattening of the mass function at M_star ~ 0.5 M_sun. 
Anlaug Amanda Kaas (1,2) and Sylvain Bontemps (3) ((1) ESTEC, The   Netherlands, (2) Nordic Optical Telescope, Spain, (3) Ob...