The candidates for Class I methanol masers

Abstract

The collisional excitation of methanol molecule in non-dissociative magnetohydrodynamic shock waves is considered. All essential chemical processes that determine methanol abundance in the gas are taken into account in the shock model. The large velocity gradient approximation is used in the calculations of energy level populations of the molecule. We calculate the optical depth for inverted methanol transitions, and present the list of candidates for Class I methanol masers that have collisional pumping mechanism.