Massive young stellar objects with molecular outflows

We studied three members of the sample of 31 cold and luminous southern IRA S sources, which was compiled by Osterloh et al. (1997). These young stella r objects are characterized by extremely red IRAS colours [S-v(100 mu m) > S-v(60 mu m) > S-v (25 mu m) > 20 x S-v (12 mu m)]. Based on their strong C O line wings found in previous observations, the three objects IRAS 12091-6 129, IRAS 12405-6238, and IRAS 16019-4903 were selected in order to investi gate their nature and the outflow structure in more detail. The mapping in the CO J = 2 --> 1 line as well as the lambda 1.3 mm continu um dust emission show that all three sources are deeply embedded in dense c loud cores. Strong CO line wings and their mapping indicate the presence of bipolar gas outflows in all three cases. N- and Q-band imaging resolve some substructures inside the lambda 1.3 mm m aps and give evidence for deeply embedded young stellar objects which seem to drive the observed outflows. The comparison of the FIR imaging with the results in Ii imply that most of the K-band nebulosities are reprocessed ra diation escaping through inhomogeneities in a dense cloud. We derived physical parameters such as H-2 column densities and cloud core masses from the CO and the bolometer measurements, and we compared the prop erties of the outflows and of the surrounding clouds with those found for w ell-known high-, intermediate- and low-mass objects. This comparison showed that the newly detected outflow systems belong to the most energetic outfl ows in our galaxy observed so far.