Potential of a combined optical/NIR diagnostics for protostellar jets

The possible existence of supersonic protostellar jets around Brown Dwarfs can shed light on obscure aspects of their formation mechanism. To study this subject one has to start from a firm knowledge of the properties of jets associated with solar-mass stars. We have studied recently the conditions of the plasma along a number of classical stellar jets through a combined optical-infrared diagnostics, applied to moderate spatial/spectral resolution spectra (taken with 3.6m-EFOSC2 and NTT-SOFI). From the fluxes of the emission lines in the range 0.6-2.5 μm we have derived important parameters such as the variation of the visual extinction along the flow, the electron and total density, the ionization fraction, the electronic temperature and the mass flux in the jet channel. Moreover, combining the optical and NIR information we have investigated the relative spatial distribution of the emission lines, and the depletion of emitting refractory species such as Calcium, Carbon and Iron, that are related to the presence of dust in the flow. Results of this kind are very useful for planning observations to identify jets from Brown Dwarfs and analyse their properties.