OH masers in star-forming regions: Interpretation of observations

Abstract

OH masers are a potentially powerful probe of the physical conditions in massive star-forming regions, giving detailed information on the kinetic and dust temperatures, number densities of H2 and OH, bulk flows and magnetic fields in the vicinity of massive young stellar objects. ^Using current theories and data, we describe how bright maser spots, as seen in VLBI at 18 cm, 6 cm and 5 cm, may arise and we outline the physical conditions which may be associated with masers at different frequencies.