7 Conclusions

1.

Observations of 158 sources in the CS(2-1) line have been carried out (111 bipolar outflows, 26 Class I methanol masers, and 47 Class II methanol masers, 10 sources are Class I and Class II methanol masers simultaneously), with 149 positive results (97 bipolar outflows, 26 Class I methanol masers, and 45 Class II methanol masers). Out of these 149 sources, 51 have been observed in C³⁴S. All sources observed in the C³⁴S line show positive results.

2.

The main feature of the CS line for Class I methanol masers, is on average, wider than for bipolar outflows and Class II methanol masers.

3.

A complex line shape was observed in 52$\%$ of bipolar outflows, in 23$\%$ of Class I methanol masers, and in 37$\%$ of Class II methanol masers. Considering the pedestal of a line as wings, one can see that the range of the wings of the CS lines is insignificant.

4.

The column density in methanol masers, both of Class I and Class II, is higher than in bipolar outflow centres.

5.

Assuming that all sources are "point sources'' for the beam of the Onsala radio telescope, we conclude that the dependence between the CS luminosity and the IR luminosity has been proven. Methanol masers, both of Class I and Class II, are stronger than bipolar outflows both in the IR continuum and in the CS line. Methanol masers of both classes are formed in denser regions than bipolar outflows.

6.

The statistical characteristics of the regions forming Class I methanol masers are different from those both in the centres of bipolar outflows and in the regions forming Class II methanol masers, based on the values of the average antenna temperature, average column density, and IR luminosities in the CS(2-1) line. It is possible that physical conditions in bipolar outflows are closer to physical conditions of Class II methanol masers.

Acknowledgements

We are grateful to V.I. Slysh, S.V. Kalenskii, A.M. Dzura, and M.A. Voronkov for critically reading the manuscript, G.M.L, I.E.V. & V.V.G. are grateful also to R. Hammargren for the excellent professional skill during the time of our observations. This work (G.M.L., I.E.V. & V.V.G.) was supported by the Russian Foundation for Basic Research (grant No. 95-02-05826). The observations were carried out during the stay of G.M.L. and I.E.V. at the Onsala Space Observatory with support from the Swedish Royal Academy of Sciences. The Onsala Space Observatory is the Swedish National Facility for Radio Astronomy and is operated by Chalmers University of Technology, Göteborg, Sweden, with financial support from the Swedish Natural Science Research Council and the Swedish Board for Technical Development.

 

Figures i,ii (Online edition only)

Figure i: Spectra of the CS(2-1) line

 

Figure i: Continued

 

Figure i: Continued

 

Figure i: Continued

 

Figure i: Continued

 

Figure i: Continued

 

Figure i: Continued

 

Figure i: Continued

 

Figure i: Continued

  

Figure ii: Spectra of the CS(2-1) and C34S(2-1) lines.

 

Figure ii: Continued

 

Figure ii: Continued

 

Figure ii: Continued

 

Figure ii: Continued