Water line emission in low-mass protostars

Ceccarelli, C.; Loinard, L.; Caux, E.; Castets, A.; Tielens, A. G. G. M.; Molinari, S.; Liseau, R.; Smith, H. and White, G. (1999). Water line emission in low-mass protostars. In: The Physics and Chemistry of the Interstellar Medium, 22-25 Sep 1998, Zermatt, p. 283.

URL: http://adsabs.harvard.edu/abs/1999pcim.conf..283C


In the quiescent ISM, most water molecules are believed to be frozen in the icy mantles of the dust grains (e.g. van Dishoeck & Blake 1998). However, if a phenomenon energetic enough to evaporate or destroy those mantles occurs, water can be released into the gas phase. In addition, at temperature larger than about 250 K, endothermic reactions in the gas phase can efficiently transform the oxygen not locked into CO molecules into H2O molecules (Graff & Dalgarno 1987). Both effects can lead to high enhancements of the water gas phase abundance, and lead to intense emission in its far infrared rotational lines. Energetic phenomena and heating are known to occur near low-mass protostars: powerful outflows create strong shocks (e.g. Hollenbach & McKee 1989; Kaufman & Neufeld 1996), while in the infalling envelopes, heating due to the central source and/or compression of the gas, may be sufficient to produce large over-abundances of water (Ceccarelli, Hollenbach & Tielens 1996).

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