Ring structures in Orion KL

We present the results of studies of the superfine structure of H2O maser s ources in the Orion Nebula. Powerful, low-velocity, compact maser sources a re distributed in eight active zones. Highly organized structures in the fo rm of chains of compact components were revealed in two of these, in the mo lecular cloud OMC-1. The component sizes are similar to 0.1 AU and their br ightness temperatures are T-b = 10(12)-10(16) K. The structures correspond to tangential sections of concentric rings viewed edge-on. The ring emissio n is concentrated in the azimuthal plane, decreasing the probability of the ir discovery. The formation of protostars is accompanied by the development of accretion disks and bipolar hows, with associated H2O maser emission. T he accretion disks are in the stage of fragmentation into protoplanetary ri ngs. In a Keplerian approximation, the protostars have low masses, possibly evidence for instability of the systems. Supermaser emission of the rings is probably triggered by precession of the accretion disk. The molecular cl oud's radial velocity is V-LSR = 7.74 km/s and its optical depth is tau app roximate to 5. The emission from components with velocities within the mase r window is additionally amplified. The components emission is linearly pol arized via anisotropic pumping. (C) 2000 MAIK "Nauka/Interperiodica".