The environment of the strongest galactic methanol maser
  The high-mass star-forming site G009.62+00.20E hosts the 6.7 GHz methanol
maser source with the greatest flux density in the Galaxy which has been
flaring periodically over the last ten years. We performed high-resolution
astrometric measurements of the CH3OH, H2O, and OH maser emission and 7 mm
continuum in the region. The radio continuum emission was resolved in two
sources separated by 1300 AU. The CH3OH maser cloudlets are distributed along
two north-south ridges of emission to the east and west of the strongest radio
continuum component. This component likely pinpoints a massive young stellar
object which heats up its dusty envelope, providing a constant IR pumping for
the Class II CH3OH maser transitions. We suggest that the periodic maser
activity may be accounted for by an independent, pulsating, IR radiation field
provided by a bloated protostar in the vicinity of the brightest masers. We
also report about the discovery of an elliptical distribution of CH3OH maser
emission in the region of periodic variability.
