Star formation in the Vela Molecular Clouds - III. Near IR images and mm photometry of D-cloud IRAS sources

We present the rst results of a sensitive (K 17 mag) near IR (JHK) imaging survey of a complete IRAS selected sample of Young Stellar Objects (YSO's) belonging to a Giant Molecular Cloud (GMC) located in the Vela Molecular Ridge (VMR). We provide accurate po- sition and photometry for more than 1300 sources, along with the identication of possible NIR counterparts of the IRAS objects. Through near infrared and 1.3 mm photom- etry we have determined the spectral energy distributions of 11 newly discovered Class I sources and possibly one Herbig Ae/Be star. Their bolometric luminosities indicate that they are protostellar objects of intermediate masses ( 10M) with envelopes containing a not negligible frac- tion of the central condensed matter. Many sources are as- sociated to diuse emission which hosts multiple systems of point-like objects. Although clustering is well evident, the NIR counterparts of the IRAS sources seem to be sin- gle objects and quite often there are more than one source in the eld with JHK colours typical of Class I objects. These ndings support the fact that in VMR, as well, stars of dierent masses are sharing the same birthplace.