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

TL;DR

This paper provides a detailed three-dimensional spectral atlas of the Orion Nebula across multiple ionization stages, revealing its physical structure, kinematics, and localized phenomena, and offers new insights into electron temperature and line broadening.

Contribution

It introduces a comprehensive 3D spectral atlas of the Orion Nebula in various emission lines, enabling detailed analysis of its structure and physical conditions.

Findings

Mean electron temperature of (9200 +/- 400) K determined

Non-thermal line broadening similar across different emission lines

Large-scale ionized gas behavior and localized outflows identified

Abstract

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] 6300, [S II] 6716,6731, [N II] 6584, [S III] 6312, H alpha 6563, and [O III] 5007. These transitions provide point to point information about the physical structure and kinematics of the nebula at an effective resolution of 3'' x 2'' x 10 km/s, 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 H alpha, [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.