Program: GN-2009B-Q-44

At the present time we know much less about how massive stars form compared to low mass stars. The main question is if massive stars are simply a scaled-up version of disk accretion as seen in low-mass stars. However concrete and convincing evidence for the existence of these disks around high mass stars remains elusive. One unique property of massive stars in their formative years is the presence of methanol maser emission. These masers are thought to exist in and trace either circumstellar disks around massive stars or their outflows, but there still is not enough proof for either scenario. An exciting new morphological class of methanol masers has been discovered by the co-authors of this proposal: the methanol maser ring. The methanol masers for these sources are in ring-like distributions on the sky and are on average ~0.3" in diameter (~1500AU at the typical distances to the sources). The nature of these methanol rings is unknown. They may be tracing a circumstellar disks or torii, or they may be in shocks propagating through the conical outflow cavity structures near the stars. We therefore propose to use Gemini's high resolution NIR AO and MIR imaging to pinpoint the location of the embedded massive young stars with respect to the position of the maser rings. Furthermore we will explore the nature of the circumstellar material in the near-stellar environment to see if we can resolve out disk or outflow structures. This set of maser ring sources provide a promisingly unique sample which may shed light onto the main question at the very heart of massive star formation.