Production of 12.2 GHz CH3OH masers — Preliminary results of an excitation study

Abstract

Excitation of the 2(0) - 3(-1)E transition of CH3OH at 12.2 GHz has been examined in a statistical equilibrium study. ^The results show that maser emission can be produced in a molecular cloud with a bright H II region as immediate background. ^ For a cloud of kinetic temperature of 30 K, velocity gradient of 5 km/s/pc, H2 density of about 10 exp 5/cu cm and methanol abundance of 10 exp -6, and a continuum background of 50 K, the maser emission can reach a brightness temperature of about 1300 K. This value would be much higher with smaller velocity gradient, where bright maser emission is usually expected. ^(Author (revised))