On the evolution of the molecular line profiles induced by the propagation of C-shock waves

Abstract

We present the first results of the expected variations of the molecular line emission arising from material recently affected by C-shocks (shock precursors). Our parametric model of the structure of C-shocks has been coupled with a radiative transfer code to calculate the molecular excitation and line profiles of shock tracers such as SiO, and of ion and neutral molecules such as H13CO+ and HN13C, as the shock propagates through the unperturbed medium. Our results show that the SiO emission arising from the early stage of the magnetic precursor typically has very narrow line profiles slightly shifted in velocity with respect to the ambient cloud. This narrow emission is generated in the region where the bulk of the ion fluid has already slipped to larger velocities in the precursor as observed toward the young L1448-mm outflow. This strongly suggests that the detection of narrow SiO emission and of an ion enhancement in young shocks, is produced by the magnetic precursor of C-shocks. In addition, our model shows that the different velocity components observed toward this outflow can be explained by the coexistence of different shocks at different evolutionary stages, within the same beam of the single-dish observations.

7 pages, 4 figures, accepted for publication in ApJ

References in corpus (8)

• Magnetic Fields in the Formation of Sun-Like Stars
• SiO line emission from C-type shock waves : interstellar jets and outflows
• Parametrization of C-shocks. Evolution of the Sputtering of Grains
• Warm SiO gas in molecular bullets associated with protostellar outflows
• PdBI sub-arcsecond study of the SiO microjet in HH212 - Origin and collimation of Class 0 jets
• HCO mapping of the Horsehead : Tracing the illuminated dense molecular cloud surfaces
• Organic chemistry in the dark clouds L1448 and L183. A Unique grain mantle composition
• First Measurements of the Electron Density Enhancements Expected in C-shocks

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