2004ApJ...603L.113P

We present an edge-on Keplerian disk model to explain the main component of the 12.2 and 6.7 GHz methanol maser emission detected toward NGC 7538 IRS 1N. The brightness distribution and spectrum of the line of bright masers are successfully modeled with high amplification of background radio continuum emission along velocity-coherent paths through a maser disk. The bend seen in the position-velocity diagram is a characteristic signature of differentially rotating disks. For a central mass of 30 M_☉, suggested by other observations, our model fixes the masing disk to have inner and outer radii of ∼350 and ∼1000 AU.