Water in star-forming regions with Herschel (WISH) - II. Evolution of 557 GHz 110–101 emission in low-mass protostars

摘要

Context. Water is a key tracer of dynamics and chemistry in low-mass star-forming regions, but spectrally resolved observations have so far been limited in sensitivity and angular resolution, and only data from the brightest low-mass protostars have been published. Aims. The first systematic survey of spectrally resolved water emission in 29 low-mass (L?10?km?s-1). The water abundance in the outer cold envelope is low, ??10-10. The different H2O profile components show a clear evolutionary trend: in the younger Class?0 sources the emission is dominated by outflow components originating inside an infalling envelope. When large-scale infall diminishes during the Class?I phase, the outflow weakens and H2O emission all but disappears.