NEWLY DISCOVERED GALACTIC H2O MASERS ASSOCIATED WITH OUTFLOWS

We have discovered 17 new H2O masers in searches of known molecular ou tflows in regions of star formation and have investigated their time v ariations (see also Xiang and Turner 1992). We have also made extensiv e surveys of the literature to enumerate all previous H2O masers and o utflows and have examined the IRAS Point Source Catalog for IRAS sourc es toward these objects. Together with the results of a recent survey for molecular outflows in directions of known H2O masers, we are able to assess the success ratio for detections of masers toward known outf lows, and for detections of outflows toward known masers. Conclusions about the causal relations between IRAS objects, masers, and outflows are drawn. In particular, we suggest that lifetimes and formation cond itions for H2O masers and outflows are similar, or causally related. T his is consistent with models of H2O masers in star-forming regions (E litzur et al. 1989) in which the masers are formed and pumped by gas h eated by dissociative shocks, assuming that the shocks are produced by the outflows. Our new information on H2O maser time variations sugges ts that such variations are unimportant in making these conclusions.