5. Conclusions

We have detected and mapped the ammonia emission in 14 sources of a sample of 15 sources associated with molecular and/or optical outflows. In addition, we have searched for maser emission towards 9 regions, and detected a weak maser near IRAS 20188+3928. Our main conclusions drawn from this study can be summarized as follows:

1. In all the molecular outflow regions we have mapped, the \ emission peak is very close to the position of a good candidate for the outflow exciting source.
2. For the two regions with only optical outflow (HH 84 and HH 86/87/88), no object is detected towards the observed (weak) \ condensations, suggesting a non local origin for the flow excitation.
3. We found that, in general, the condensations are very cold, with line widths dominated by non thermal (turbulent) motions. Among the observed sources, IRAS 20188+3928 appears to be the object that produces a larger perturbation in its molecular high density environment. Evidence for disruption of the L1228 core has also been found.
4. The ammonia condensations appear to be, in general, close to virial equilibrium. L483 is remarkable in being associated with the largest visual extinction of our sample and being in a possible gravitational collapse, making this source a very good candidate to be a very young deeply embedded object.
5. A very elongated structure, apparently associated with several young objects and with strong velocity gradients, has been found near IRAS 22376+7455 in L1251.
6. Our main result is the discovery of a correlation between the intensity of the emission and the presence of molecular or optical outflow. The brightness temperature and column density decrease as the outflow activity becomes prominent in the optical. This result suggests an evolutive scheme in which young objects lose progressively their neighboring high density gas. More observations towards the exciting sources of optical jets and HH objects could be very useful to increase the sample in order to allow a more detailed study.

Acknowledgements

We thank the referee, R. Cesaroni, for his careful review of the paper. G.A. and J.F.G. acknowledge support from DGICYT grant PB92-0900, Spain. J.F.G. is also supported by Junta de Andalucía, Spain.