SEARCHING FOR PROTOSTARS

We present molecular-line observations of young stellar objects (YSOs) suspected to be protostars in the main accretion phase. The aim of th is work is to define a list of the best protostellar candidates to be observed in the near future with the ISO spectrometers with the precis e scope of searching for the final proof of the infall, the Holy Grail of astrophysics. The sources were mapped in the CS 3 --> 2 and CO 3 - -> 2 lines; our data were used to investigate the presence of clumps o f materials around these objects and the amount of this material, as w ell as to detect outflows associated with these objects that would eno rmously complicate the interpretation of further dynamics studies. Onl y one of our sources suspected to be protostars resulted to have a goo d chance of being in the accretion phase and to deserve further spectr oscopic measurements.