As part of the GT Herschel Program CHESS we detected for the first time hydrogen chlorine in a protostellar shock, L1157-B1 (Codella et al. 2011). One of the most surprising results of this work was the lack of enhancement in the abundance of HCl with respect to dense interstellar clouds, implying that HCl is not enhanced by the passage of a shock. This means that either chlorine is not sputtered during the passage of the shock (unlikely as Si is sputtered) or that HCl is not the main reservoir of clorine in shocked regions (unlike in dense interstellar clouds). In this proposal we propose to observe HCl in a sample of shocked regions in order to determine whether this result is unique to L1157-B1. We stress that given the weakness of the HCl emission in shocks and the strong atmospheric water absorption at the requested frequency (626 GHz), the present experiment cannot be reasonably performed from ground, making of Herschel OT2 the last chance to reach the present goals.
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.