1996A&A...310..309B

The physical properties of the optical jet associated with the T Tauri star RW Aurigae are discussed. The excitation temperature, the hydrogen ionization fraction, the electron and gas densities are estimated in various positions along the flow axis using a diagnostic technique originally developed for the study of the physical conditions in highly collimated Herbig-Haro jets (Bacciotti, Chiuderi & Oliva 1995). The receding portion of the jet (red lobe) has an ionization fraction which is slowly decreasing from about 25% near the star to about 2% at a distance of 6-7" (∼1000AU); the hydrogen density is roughly constant with a value of about 10⁴cm^–3; the temperature shows a slight decline, with typical values of about 4500K. These results are consistent with the idea that the gas is initially ionized in the jet acceleration zone and that the physical conditions in the visible part of the jet are determined by time-dependent hydrogen recombination. It has not been possible to obtain any result for the blue lobe, due to the weakness of the [SII] 6716,6731A lines. The mass-loss and momentum rate in the flow (red lobe) are {dot}(M)∼5x10^–8M_☉/yr and {dot}(P)∼6.5x10^–6M_☉/yr.km/s.