Radio recombination lines from fast shocks in molecular clouds, with application to bipolar flows

Detailed shock calculations are presented which demonstrate that fast dissociative shocks in molecular clouds produce detectable radio recombination lines and continuum lines, in addition to optical and infrared recombination lines. The theoretical results are applied to outflows from young stellar objects; bipolar flows are treated as massive, radiative winds. The calculations support Hasegawa and Akabane's (1984) interpretation of the H51-alpha line from Orion-KL as being due to a shock, and are consistent with the two-shock model of Chernoff, Hollenbach, and McKee (1982).