Studies of methanol maser rings
  We present the results of studies of a new class of 6.7 GHz methanol maser
sources with a ring-like emission structure discovered recently with the EVN.
We have used the VLA to search for water masers at 22 GHz and radio continuum
at 8.4 GHz towards a sample of high-mass star forming regions showing a
ring-like distribution of methanol maser spots. Using the Gemini telescopes we
found mid-infrared (MIR) counterparts of five methanol rings with a resolution
of 0."15. The centres of methanol maser rings are located within, typically,
only 0."2 of the MIR emission peak, implying their physical relation with a
central star. These results strongly support a scenario wherein the ring-like
structures appear at the very early stage of massive star formation before
either water-maser outflows or H II regions are seen.
