Backscattering and Line Broadening in Orion

C. R. O’Dell; G. J. Ferland; J. E. Méndez-Delgado

doi:10.3847/1538-3881/ac9f44

Backscattering and Line Broadening in Orion

C. R. O’Dell, G. J. Ferland, J. E. Méndez-Delgado

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4 Scopus citations

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 Alfvén waves in conditions where the ratio of magnetic and thermal energies are about equal and constant throughout the ionized gas.

Original language	English
Article number	21
Journal	Astronomical Journal
Volume	165
Issue number	1
DOIs	https://doi.org/10.3847/1538-3881/ac9f44
State	Published - Jan 1 2023

Bibliographical note

Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-3881/ac9f44

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title = "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 Alfv{\'e}n waves in conditions where the ratio of magnetic and thermal energies are about equal and constant throughout the ionized gas.",

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AU - O’Dell, C. R.

AU - Ferland, G. J.

AU - Méndez-Delgado, J. E.

PY - 2023/1/1

Y1 - 2023/1/1

N2 - 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 Alfvén waves in conditions where the ratio of magnetic and thermal energies are about equal and constant throughout the ionized gas.

AB - 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 Alfvén waves in conditions where the ratio of magnetic and thermal energies are about equal and constant throughout the ionized gas.

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Backscattering and Line Broadening in Orion

Abstract

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ASJC Scopus subject areas

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