The three dimensional dynamic structure of the inner Orion Nebula

Abstract

The three dimensional structure of the brightest part of the Orion Nebula is assessed in the light of published and new data. We find that the widely accepted model of a concave blister of ionized material needs to be altered in the southwest direction from the Trapezium, where we find that the Orion-S feature is a separate cloud of very optically thick molecules within the body of ionized gas, which is probably the location of the multiple embedded sources that produce the outflows that define the Orion-S star formation region. Evidence for this cloud comes from the presence of H2CO lines in absorption in the radio continuum and discrepancies in the extinction derived from radio-optical and optical only emission. We present an equilibrium Cloudy model of the Orion-S cloud, which successfully reproduces many observed properties of this feature. We also report the discovery of an open-sided shell of [O III] surrounding the Trapezium stars, revealed through emission line ratio images and the onset of radiation shadows beyond some proplyds. We show that the observed properties of the shell are consistent with it being a stationary structure, produced by shock interactions between the ambient nebular gas and the high-velocity wind from theta^1 Ori C. We examine the implications of the recently published evidence for a large blueshifted velocity of theta^1 Ori C with respect to the Orion Molecular Cloud, which could mean that this star has only recently begun to photoionize the Orion Nebula. We show that current observations of the Nebula do not rule out such a possibility, so long as the ionization front has propagated into a pre-existing low-density region. In addition, a young age for the Nebula would help explain the presence of nearby proplyds with a short mass-loss timescale to photoablation.

AJ in press, 18 pages, 7 figures (2 in full color)

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• Expanding bubbles in Orion A: [CII] observations of M42, M43, and NGC 1977
• Nested shells reveal the rejuvenation of the Orion-Eridanus superbubble
• Tearing the Veil: interaction of the Orion Nebula with its neutral environment
• Evidence for feedback and stellar-dynamically regulated bursty star cluster formation: the case of the Orion Nebula Cluster
• The Orion HII Region and the Orion Bar in the Mid-Infrared
• A Wide-Field Survey of the Orion Nebula Cluster in the Near-Infrared
• The Hubble Space Telescope Treasury Program on the Orion Nebula Cluster
• PDRs4All II: JWST's NIR and MIR imaging view of the Orion Nebula
• 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
• Towards the field binary population: Influence of orbital decay on close binaries
• Photoevaporation and spatial variation of grain sizes in Orion 114-426
• Intracluster Age Gradients In Numerous Young Stellar Clusters
• Excitation of Molecular Hydrogen in the Orion Bar Photodissociation Region From a Deep Near-Infrared IGRINS Spectrum
• Herschel / HIFI spectral line survey of the Orion Bar - Temperature and density differentiation near the PDR surface
• A New Class of Nascent Eclipsing Binaries with Extreme Mass Ratios
• Modelling massive-star feedback with Monte Carlo radiation hydrodynamics: photoionization and radiation pressure in a turbulent cloud
• Turbulence in the Ionized Gas of the Orion Nebula
• The extinction map of the OMC-1 molecular cloud behind the Orion Nebula
• Structure and Physical Conditions in the Huygens Region of the Orion Nebula
• Integral field spectroscopy of selected areas of the Bright Bar and Orion-S cloud in the Orion Nebula
• The structure of the Orion Nebula in the direction of Theta 1 Ori C
• The Nature and Frequency of Outflows from Stars in the Central Orion Nebula Cluster
• Carbon radio recombination lines from gigahertz to megahertz frequencies towards Orion A
• Orion's Veil: Magnetic field strengths and other properties of a PDR in front of the Trapezium Cluster
• Deciphering the 3-D Orion Nebula-I: Expanding Shells in the Huygens Region
• Messenger Monte-Carlo MAPPINGS V (M^3) -- A self-consistent three-dimensional photoionization code
• X-ray embedded stars as driving sources of outflow-driven turbulence in OMC1-S
• PDRs4All VI: Probing the Photochemical Evolution of PAHs in the Orion Bar Using Machine Learning Techniques
• Layers in the Central Orion Nebula
• Chemical abundances in Orion protoplanetary discs: integral field spectroscopy and photoevaporation models of HST 10
• Observation and calibration strategies for large-scale multi-beam velocity-resolved mapping of the [CII] emission in the Orion molecular cloud
• Molecular tracers of radiative feedback in Orion (OMC-1). Widespread CH+ (J=1-0), CO (10-9), HCN (6-5), and HCO+ (6-5) emission
• Scattered Nebular Light in the Extended Orion Nebula
• MUSE view of PDS 456: kpc-scale wind, extended ionized gas and close environment
• Dents in the Veil: Protostellar feedback in Orion
• Kinematics of the Orion Trapezium Based on Diffracto-Astrometry and Historical Data
• SIRIUS Project. V. Formation of off-center ionized bubbles associated with Orion Nebula Cluster
• Dramatic Evolution of the Disk-Shaped Secondary in the Orion Trapezium Star Theta1 Ori B1 (BM Ori): MOST Satellite Observations
• Multiline observations of hydrogen, helium, and carbon radio-recombination lines toward Orion A: A detailed dynamical study and direct determination of physical conditions
• Hydrostatic photoionization models of the Orion Bar
• First Science Observations with SOFIA/FORCAST: 6 to 37 micron Imaging of the Central Orion Nebula
• 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
• IRAS 09002-4732: A Laboratory for the Formation of Rich Stellar Clusters
• 3D structure of HII regions in the star-forming complex S254-S258
• Deciphering the 3-D Orion Nebula-III: Structure on the NE boundary of the Orion-S Embedded Molecular Cloud
• The Integral Field View of the Orion Nebula