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Astron. Astrophys. 321, 311-322 (1997)

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6. Summary and conclusions

  1. We observed 12 regions of massive star formation in the [FORMULA] series of methanol lines near 96 GHz. Emission was detected toward all the observed sources. Radial velocities of the lines proved to be similar to the radial velocities of the methanol lines [FORMULA] near 157 GHz. The linewidths at 96 GHz are slightly smaller than those at 157 GHz, suggesting that the optical depths at 96 GHz are smaller.
  2. We derived a number of source parameters both analytically and using statistical equilibrium calculations. The parameters determined by the two methods are close to each other. However, our estimates are based on simplified source models and at best represent some typical source parameters.
  3. The source densities vary in the range [FORMULA] and kinetic temperatures in the range 15-50 K. Source sizes are of the order of [FORMULA] cm; similar sizes were obtained from the interferometric observations of some star-forming regions in the lines of CS and of other high-density gas tracers. Methanol abundance can be determined only with large errors; the values which provide the best agreement with the observational data for all sources except Cep A are enclosed in the range [FORMULA], typical for dark clouds rather than for "hot cores".
  4. Broad components were detected in the 96 GHz spectra of several objects. These wings are probably connected with high-velocity motions in star-forming regions (bipolar outflows, cometary bow shocks of HII regions).
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© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998