  The complete near infrared (0.9-2.5 micron) spectra in three different star
forming regions (HH24-26, HH72 and BHR71) are presented and analyzed in the
framework of shock excitation models. The spectra are dominated by H_2
rovibrational emission (vibrational state nu up to 5, excitation energy T_ex up
to 35000 K), while emission from ionized material, recognizable from [Fe II]
and [S II] lines, is significantly fainter. The analysis of the H_2 excitation
diagrams points to the existence of two different excitation regimes: whilst
condensations observed only in the infrared appear to have temperatures rarely
exceeding 3000 K and can be modelled in the framework of steady-state C-shock
models, the infrared counterparts of Herbig Haro (HH) objects exhibit a
temperature stratification with components up to more than 5000 K. The H_2
emission from representative HH objects (HH26A, HH72A and HH320A) has been
successfully modelled by planar J-shocks with magnetic precursors, for which
the main parameters (pre-shock density, speed) are derived. However, these same
models are unable to reproduce the observed atomic and ionic emission, which
probably arises from a distinct and perhaps more embedded region with respect
to that traced by the H_2. Some of the physical parameters of such regions
(fractional ionization, density) have been estimated in HH72, on the basis of
the observed ionic lines.
