VLBI observations of 6.7 and 12.2 GHz methanol masers toward high mass star-forming regions - II. Tracing massive protostars

We compare the absolute positions of methanol maser sites with those of typ ical tracers of young massive stellar objects, such as ultra-compact HII re gions, outflows and hot molecular cores. We have selected thirteen star-for ming regions for which we have produced VLBI maps of 6.7 and 12.2 GHz metha nol masers, and for which complementary high resolution images are availabl e in the literature. These sources are namely: IRAS 20126+4104, NGC 7538, S 252, G 31.28+0.06, W 75N, S 255, S 269, Mon R2, G 9.62+0.20, Cep A, W 51, C, 59.78+0.06 and G 29.95-0.02. Eight of the methanol maser sources coincid e in position within 2000 AU with outflows and/or hot molecular cores, i.e. phenomena occuring at the earliest stage of massive star formation. Only t wo sources coincide in position with hyper-compact HII regions. We conclude that 6.7 and 12.2 GHz methanol masers are likely to be one of the first si gnposts of massive star formation and perhaps the first signpost of a massi ve protostar.