I will present the results of spectral energy distribution analysis for 162 of the 405 sources reported in the SIMBA survey of Hill et al. (2005). The fits reveal six parameters; the luminosity, mass, temperature, H2 number density, the surface density and the luminosity-to-mass ratio.

Analysis reveals a clear temperature and luminosity distinction amongst the four classes of source. Intriguingly, the mm-only cores (without methanol maser and UC HII) are of comparable mass to sources with a methanol maser association whilst collectively these two classes are slightly less massive than cores with UC HII. The mm-only cores are smaller, less luminous, and cooler than the other sources, with at least 45 % devoid of mid-infra red MSX emission. This has led us to propose that the mm-only cores are a precursor to the methanol maser in the ormation of massive stars.

The mm-only cores comprise two distinct populations distinguished by temperature. The cool-mm are distinctly different from the warm-mm and those sources with methanol masers and UC HII regions. The cool-mm sources have smaller radii, are less luminous with lower luminosity-to-mass ratios, and are more dense, with higher H2 number and surface densities. The warm-mm sources on the other hand display similar characteristics to sources with a methanol maser and/or radio continuum source. These results suggest that the warm-mm cores are the precursors to the methanol maser sources, whilst the cool-mm sources are examples of failed cores (Vazquez-Semadeni et al. 2005).

ethanol maser emission has proven to be an excellent tracer of regions undergoing massive stars formation. We have recently completed a large observing program with the ATCA to investigate the dynamical and physical properties of molecular/ionised gas towards a sample of massive star formation regions traced by 6.7\,GHz methanol maser emission. We find that the molecular gas in many of these regions breaks up into multiple sub-clumps which we separate into groups based on their association with/without methanol maser and cm continuum emission. The temperature and dynamic state of the molecular gas is markedly different between the groups. We attempt to assess the evolutionary state of the cores in the groups and thus investigate the role of class II methanol masers in massive star formation.