Methanol masers in HII regions

Based on the positions of the Class I and II methanol and H_2_O masers, UC HII regions and 4.5um infrared sources, and the center velocities (vLSR) of the Class I methanol and H_2_O masers, compared to the vLSR of the Class II methanol masers, we propose three disk-outflow models that may be traced by methanol masers.

In all three models, we have located the Class II methanol maser near the protostar, and the Class I methanol maser in the outflow, as is known from observations during the last twenty years. In our first model, the H_2_O masers trace the linear extent of the outflow. In our second model, the H_2_O masers are located in a circumstellar disk.