We present infrared echelle spectroscopy of three Herbig-Haro ( HH ) driving sources ( SVS 13 , B5-IRS 1 and HH 34 IRS ) using Subaru-IRCS .
The large diameter of the telescope and wide spectral coverage of the spectrograph allowed us to detect several H _ { 2 } and [ Fe II ] lines in the H - and K -bands .
These include H _ { 2 } lines arising from v =1–3 and J =1–11 , and [ Fe II ] lines with upper level energies of E / k = 1.1 - 2.7 \times 10 ^ { 4 } K. For all objects the outflow is found to have two velocity components : ( 1 ) a high-velocity ( - 70 to - 130 km s ^ { -1 } ) component ( HVC ) , seen in [ Fe II ] or H _ { 2 } emission and associated with a collimated jet ; and ( 2 ) a low-velocity ( - 10 to - 30 km s ^ { -1 } ) component ( LVC ) , which is seen in H _ { 2 } emission only and is spatially more compact .
Such a kinematic structure resembles optical forbidden emission line outflows associated with classical T Tauri stars , whereas the presence of H _ { 2 } emission reflects the low-excitation nature of the outflowing gas close to these protostars .
The observed H _ { 2 } flux ratios indicate a temperature of 2 - 3 \times 10 ^ { 3 } K , and a gas density of 10 ^ { 5 } cm ^ { -3 } or more , supporting shocks as the heating mechanism .
B5-IRS 1 exhibits faint extended emission associated with the H _ { 2 } -LVC , in which the radial velocity slowly increases with distance from the protostar ( by \sim 20 km s ^ { -1 } at \sim 500 AU ) .
This is explained as warm molecular gas entrained by an unseen wide-angled wind .
The [ Fe II ] flux ratios indicate electron densities to be \sim 10 ^ { 4 } cm ^ { -3 } or greater , similar to forbidden line outflows associated with classical T Tauri stars .
Finally the kinematic structure of the [ Fe II ] emission associated with the base of the B5-IRS 1 and HH 34 IRS outflows is shown to support disk-wind models .