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 | |
| State | Published - Jan 1 2023 |
Bibliographical note
Funding Information:The HIRES data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
Funding Information:
We are grateful to W. J. Henney of the Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónomia de México, Campus Morelia, México, for providing the theoretical models incorporated in Figure 3 and for his illuminating remarks on an earlier draft of this paper. Thanks are also due to David T. Chuss of Villanova University for useful discussions. J.E.M.-D. thanks the Instituto de Astrofísica de Canarias for support under the Astrophysicist Resident Program and acknowledges support from the Mexican CONACyT (grant CVU 602402).
Funding Information:
IRAF is distributed by the National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. scat mif scat mif
Funding Information:
We are grateful to W. J. Henney of the Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónomia de México, Campus Morelia, México, for providing the theoretical models incorporated in Figure and for his illuminating remarks on an earlier draft of this paper. Thanks are also due to David T. Chuss of Villanova University for useful discussions. J.E.M.-D. thanks the Instituto de Astrofísica de Canarias for support under the Astrophysicist Resident Program and acknowledges support from the Mexican CONACyT (grant CVU 602402).
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science