Molecular cloud complexes in detail : Interferometric observations of GMCs in M

We have accumulated CO(1-0) and (2-1) data of several GMCs in M31 using the Plateau de Bure Interferometer. The sample covers a range of 5 to 18 kpc galactocentric distance and various physical conditions. The spatial resolution attains values down to 3 pc. All GMCs investigated have been resolved into several components, also seemingly quiescent clouds and not only the cases where already the survey positions show obvious multiple-peaked spectra. Such kinematically disjunct emission is however spatially coincident in the small volume of the interferometer beam in M31, which strongly favours local effects as the cause of the velocity splitting. This is well consistent with the observed absence of strong streaming motions in the survey data. The nature of the sometimes strong separation in velocity space needs further investigation. The complete data set (i.e. including the large-scale survey) yields a uniquely complete view of the molecular gas which allows to investigate the conditions for star formation in detail and helps to establish guide lines for the derivation of the properties of molecular gas.