Tearing the Veil: interaction of the Orion Nebula with its neutral environment

Abstract

We present HI 21cm observations of the Orion Nebula, obtained with the Karl G. Jansky Very Large Array, at an angular resolution of 7.2"x5.7" and a velocity resolution of 0.77 km/s. Our data reveal HI absorption towards the radio continuum of the HII region, and HI emission arising from the Orion Bar photon-dominated region (PDR) and from the Orion-KL outflow. In the Orion Bar PDR, the HI signal peaks in the same layer as the H2 near-infrared vibrational line emission, in agreement with models of the photodissociation of H2. The gas temperature in this region is approximately 540K, and the HI abundance in the interclump gas in the PDR is 5-10% of the available hydrogen nuclei. Most of the gas in this region therefore remains molecular. Mechanical feedback on the Veil manifests itself through the interaction of ionized flow systems in the Orion Nebula, in particular the Herbig-Haro object HH202, with the Veil. These interactions give rise to prominent blueward velocity shifts of the gas in the Veil. The unambiguous evidence for interaction of this flow system with the Veil shows that the distance between the Veil and the Trapezium stars needs to be revised downwards to about 0.4pc. The depth of the ionized cavity is about 0.7pc, which is much smaller than the depth and the lateral extent of the Veil. Our results reaffirm the blister model for the M42 HII region, while also revealing its relation to the neutral environment on a larger scale.

accepted for publication in the Astrophysical Journal; version with full-resolution figures can be downloaded from http://www.strw.leidenuniv.nl/~pvdwerf/Orion/Orion.pdf

References in corpus (18)

• The distance to the Orion Nebula
• Diagnostics of irradiated dense gas in galaxy nuclei. II. A grid of XDR and PDR models
• Million-Degree Plasma Pervading the Extended Orion Nebula
• Explosive Outflows Powered by the Decay of Non-Hierarchical Multiple Systems of Massive Stars: Orion BN/KL
• Properties of the ionized gas in HH202. II: Results from echelle spectrophotometry with UVES
• Visual/infrared interferometry of Orion Trapezium stars: Preliminary dynamical orbit and aperture synthesis imaging of the Theta 1 Orionis C system
• A Multi-Epoch Study of the Radio Continuum Emission of Orion Source I: Constraints on the Disk Evolution of a Massive YSO and the Dynamical History of Orion BN/KL
• Orion KL: The hot core that is not a "Hot Core"
• The three dimensional dynamic structure of the inner Orion Nebula
• Spitzer reveals what's behind Orion's Bar
• The JCMT Legacy Survey of the Gould Belt: mapping 13CO and C18O in Orion A
• Spectrophotometry of the Huygens Region of the Orion Nebula, the Extended Orion Nebula, and M~43; Scattered Light Systematically Distorts Conditions Derived from Emission-Lines
• High Velocity Features in the Orion Nebula
• Rotationally Warm Molecular Hydrogen in the Orion Bar
• Large Scale Flows from Orion-South
• Discovery of an expanding molecular bubble in Orion BN/KL
• Circumbinary Molecular Rings Around Young Stars in Orion
• Hydrostatic photoionization models of the Orion Bar

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• PDRs4All III: JWST's NIR spectroscopic view of the Orion Bar
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• Modelling clumpy PDRs in 3D - Understanding the Orion Bar stratification
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• The Nature and Frequency of Outflows from Stars in the Central Orion Nebula Cluster
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• Deciphering the 3-D Orion Nebula-I: Expanding Shells in the Huygens Region
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• [CII] $158\mu \mathrm{m}$ line emission from Orion A. I. A template for extragalactic studies?
• Origin of hydrogen fluoride emission in the Orion Bar: An excellent tracer for CO-dark H2 gas clouds
• PDRs4All VI: Probing the Photochemical Evolution of PAHs in the Orion Bar Using Machine Learning Techniques
• PDRs4All. X. ALMA and JWST detection of neutral carbon in the externally irradiated disk d203-506: Undepleted gas-phase carbon
• PDRs4All. XII. FUV-driven formation of hydrocarbon radicals and their relation with PAHs
• Layers in the Central Orion Nebula
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• 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
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• Symmetry properties and widths of the filamentary structures in the Orion A giant molecular cloud
• Deciphering the 3-D Orion Nebula-III: Structure on the NE boundary of the Orion-S Embedded Molecular Cloud
• Large Scale Wind Driven Structures in the Orion Nebula
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• Photoevaporation of protoplanetary disks by Far-UV photons arising from neighbouring massive stars: observation of proplyds and modelling
• Characterizing the PAH Emission in the Orion Bar
• The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula