Near-infrared Spectrophotometry of HH 711

摘要

Near-infrared emission-line imaging and long-slit spectroscopy of H_2 and [Fe II] emission lines in the 1.252.25 μm wavelength range at multiple positions toward the Herbig-Haro objects HH 711 and a nearby H_2 emission-line source, ASR 57, are presented. The relative line strengths are used to examine the processes responsible for exciting H_2 emission in these objects. All of the H_2 emission-line ratios are consistent with collisional excitation in these objects, and no evidence is seen for noncoll- isional excitation mechanisms. Nonetheless, the H_2 level populations in HH 711 are inconsistent with LTE predictions and show underpopulations relative to a Boltzmann distribution in accordance with the different critical densities of each level.