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In a previous study of the L1157 B1 shocked cavity, a comparison betweenNH$_3$(1$_0$-$0_0$) and H$_2$O(1$_{\rm 10}$--1$_{\rm 01}$) transitions showed astriking difference in the profiles, with H$_2$O emitting at definitely highervelocities. This behaviour was explained as a result of the high-temperaturegas-phase chemistry occurring in the postshock gas in the B1 cavity of thisoutflow. If the differences in behaviour between ammonia and water are indeed aconsequence of the high gas temperatures reached during the passage of a shock,then one should find such differences to be ubiquitous among chemically richoutflows. In order to determine whether the difference in profiles observedbetween NH$_3$ and H$_2$O is unique to L1157 or a common characteristic ofchemically rich outflows, we have performed Herschel-HIFI observations of theNH$_3$(1$_0$-0$_0$) line at 572.5 GHz in a sample of 8 bright low-mass outflowspots already observed in the H$_2$O(1$_{\rm 10}$--1$_{\rm 01}$) line withinthe WISH KP. We detected the ammonia emission at high-velocities at most of theoutflows positions. In all cases, the water emission reaches higher velocitiesthan NH$_3$, proving that this behaviour is not exclusive of the L1157-B1position. Comparisons with a gas-grain chemical and shock model confirms, forthis larger sample, that the behaviour of ammonia is determined principally bythe temperature of the gas.

Diagnosing shock temperature with NH$_3$ and H$_2$O profiles