Collisional Pumping of HO and СHOH Masers in C-Type Shock Waves.

The collisional pumping of H O and СH OH masers in magnetohydrodynamic nondissociative C-type shocks is considered. A grid of C-type shock models with speeds in the range 5–70 km s and preshock gas densities – cm is constructed. The large velocity gradient approximation is used to solve the radiative transfer equation in molecular lines. The para-H O 183.3 GHz and ortho-H O 380.1 and 448.0 GHz transitions are shown to be inverted and to have an optical depth along the shock velocity at relatively low gas densities in the maser zone, – cm . Higher gas densities, cm , are needed for efficient pumping of the remaining H O masers. Simultaneous generation of H O and class I СH OH maser emission in a shock is possible at preshock gas densities cm and shock speeds in the range km s . The possibility of detecting class I СH OH and para-H O 183.3 GHz masers in star-forming regions and near supernova remnants is investigated. [ABSTRACT FROM AUTHOR]