Thermodynamics of the H <scp>ii</scp> Region Sh2-158 and “Direct” Measurement of Its Turbulence

Abstract Three SITELLE hyperspectral cubes were used to obtain 12 million spectra sampling 11 emission lines of the H ii region Sh2-158. This data set enables the calculation of numerous diagnostics and physical parameters such as abundance, electronic density, temperature, and pressure. The thermodynamic study of the nebula revealed interesting results. From [S ii ] and [N ii ] line ratio diagnostics, electronic density and temperature maps were calculated by an iterative computation method. A Monte Carlo analysis was implemented to determine accurate uncertainties for all physical parameters. We thus measured median electronic density and temperature values of 370 cm −3 and 7020 K from the iterative maps. Examining the global maps and the sampled subregions, complex patterns of density and temperature gradients/variations are observed. We produce an electronic pressure map that shows diminishing pressure, a factor of 10, from the molecular cloud to the outskirts of Sh2-158. Fabry–Perot observations complete the data to further the dynamical analysis of Sh2-158. Supersonic turbulent velocities are “directly” measured from the [N ii ] 6584 Å. Three statistical tools are used to analyze velocity centroid and nonthermal linewidth maps. The analysis of the velocity fluctuations shows the presence of intermittency. This phenomenon can produce the temperature fluctuations that are suggested to explain the abundance discrepancy problem in H ii regions.