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During the formation of a star, material is ejected along powerful jets thatimpact the ambient material. This outflow regulates star formation by e.g.inducing turbulence and heating the surrounding gas. Understanding theassociated shocks is therefore essential to the study of star formation. Wepresent comparisons of shock models with CO, H2, and SiO observations in a'pure' shock position in the BHR71 bipolar outflow. These comparisons providean insight into the shock and pre-shock characteristics, and allow us tounderstand the energetic and chemical feedback of star formation on Galacticscales. New CO (Jup = 16, 11, 7, 6, 4, 3) observations from the shocked regionswith the SOFIA and APEX telescopes are presented and combined with earlier H2and SiO data (from the Spitzer and APEX telescopes). The integrated intensitiesare compared to a grid of models that were obtained from amagneto-hydrodynamical shock code which calculates the dynamical and chemicalstructure of these regions combined with a radiative transfer module based onthe 'large velocity gradient' approximation. The CO emission leads us to updatethe conclusions of our previous shock analysis: pre-shock densities of 1e4 cm-3and shock velocities around 20-25 km s-1 are still constrained, but older agesare inferred ( 4000 years). We evaluate the contribution of shocks to theexcitation of CO around forming stars. The SiO observations are compatible witha scenario where less than 4% of the pre-shock SiO belongs to the grainmantles. We infer outflow parameters: a mass of 1.8x1e-2 Msun was measured inour beam, in which a momentum of 0.4 Msun km s-1 is dissipated, for an energyof 4.2x1e43erg. We analyse the energetics of the outflow species by species.Comparing our results with previous studies highlights their dependence on themethod: H2 observations only are not sufficient to evaluate the mass ofoutflows.

Impacts of pure shocks in the BHR71 bipolar outflow