Backscattering and Line Broadening in Orion

Abstract

Examination of emission lines in high-velocity resolution optical spectra of the Orion Nebula confirms that the velocity component on the red wing of the main ionization front emission line is due to backscattering in the Photon Dominated Region. This scattered light component has a weak wavelength dependence that is consistent with either general interstellar medium particles or particles in the foreground of the Orion Nebula Cluster. An anomalous line-broadening component that has been known for 60+ years is characterized in unprecedented detail. Although this extra broadening may be due to turbulence along the line-of-sight of our spectra, we explore the possibility that it is due to \alf\ waves in conditions where the ratio of magnetic and thermal energies are about equal and constant throughout the ionized gas.

References in corpus (9)

• Alfven Waves in the Lower Solar Atmosphere
• The Gould's Belt Distances Survey (GOBELINS) II. Distances and structure towards the Orion Molecular Clouds
• Compression and ablation of the photo-irradiated cloud the Orion Bar
• Deviations from He I Case B Recombination Theory and Extinction Corrections in the Orion Nebula
• Turbulence in the Ionized Gas of the Orion Nebula
• Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy I: HH529II and III
• Structure and Physical Conditions in the Huygens Region of the Orion Nebula
• Deciphering the 3-D Orion Nebula-I: Expanding Shells in the Huygens Region
• Deciphering the 3-D Orion Nebula-II: A low-ionization region of multiple velocity components southwest of Theta1OriC confounds interpretation of low velocity resolution studies of temperature, density, and abundance

Cited by in corpus (4)

• Density biases and temperature relations for DESIRED HII regions
• PDRs4All II: JWST's NIR and MIR imaging view of the Orion Nebula
• SDSS-V Local Volume Mapper (LVM): A Glimpse into Orion
• Multiline observations of hydrogen, helium, and carbon radio-recombination lines toward Orion A: A detailed dynamical study and direct determination of physical conditions