Velocity Structure in the Orion Nebula. II. Emission Line Atlas of Partially Ionized to Fully Ionized Gas

Ma. T. García-Díaz, W. J. Henney, J. A. López, T. Doi


We present an atlas of three-dimensional (position-position-velocity) spectra of the Orion Nebula in optical emission lines from a variety of different ionization stages: [O I] 6300Å, [S II] 6716,6731Å, [N II] 6584Å, [S III] 6312Å, Hα
6563Å, and [O III] 5007Å. These transitions provide point to point information about the physical structure and kinematics of the nebula at an effective resolution of 3" × 2" × 10 km s⁻¹, clearly showing the large scale behavior of the ionized gas and the presence of localized phenomena such as Herbig-Haro outflows. As an example application of the atlas, we present a statistical analysis of the widths of the Hα, [O III], and [N II] lines that permits a determination of the mean electron temperature in the nebula of (9200 ± 400) K. We also find, in contradiction to previous claims, that the non-thermal line broadening is not significantly different between recombination lines and collisional lines.


H II regions; ISM: Herbig-Haro objects; ISM: individual: Orion nebula; techniques: spectroscopy; turbulence

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