Description
We present the results of the observations of the (J,K)=(1,1) and the (J,K)=(2,2) inversion transitions of the NH3 molecule towards a large sample of 40 regions with molecular or optical outflows, using the 37m radio telescope of the Haystack Observatory. We detected NH3 emission in 27 of the observed regions and we mapped this emission in 25 of them. Additionally, we searched for the 6_16-5_23 H2O maser line towards six regions, detecting H2O maser emission in two of them. We estimate the physical parameters of the regions mapped in NH3 and, for each particular region, we analyze the distribution of high density gas and its relationship with the presence of young stellar objects We confirm with a larger sample of regions that the NH3 line emission is more intense towards molecular outflow sources than towards sources with optical outflow, suggesting a possible evolutionary scheme in which young stellar objects associated with molecular outflows lose progressively their neighboring high-density gas, weakening both the NH3 emission and the molecular outflow in the process, and making optical jets more easily detectable as the total amount of gas decreases.
|