| Résumé | The S255 molecular cloud has been observed using both continuum and spectral line techniques at several submillimetre and millimetre wavelengths. From photometry at 350, 760 and 1070 μm, the dust is estimated to have a central temperature of 44K and an emissivity which varies as lambda-1. Spectral mapping of the source has been carried out in the CO J=2-1, CO J=3-2 and HCN J=4-3 molecular lines, and central spectra obtained in the transitions HCO+ J=4-3 and H13CO+ J=4-3. Many features of the line observations can be modelled by assuming that the cloud is centrally condensed (with a central H2+He density of approx. 5x105 cm-3) and undergoing large-scale gravitational collapse. |
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