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

Abstract

Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud. It is important to find tracers that help quantifying the stellar feedback processes that take place at different scales. We present ~85 arcmin^2 velocity-resolved maps of several submm molecular lines toward the closest high-mass star-forming region, OMC-1. The observed rotational lines include probes of warm and dense molecular gas that are difficult to detect from ground-based telescopes: CH+ (1-0), CO (10-9), HCO+ (6-5), and HCN (6-5). These lines trace an extended but thin layer of molecular gas at high thermal pressure, P_th ~ 1e7-1e9 K/cm3, associated with the FUV-irradiated surface of OMC-1. The intense FUV field, emerging from massive stars in the Trapezium cluster, heats, compresses and photoevaporates the cloud edge. It also triggers the formation of reactive molecules such as CH+. The CH+ (1-0) emission spatially correlates with the flux of FUV photons impinging the cloud: G_0 from 1e3 to 1e5. This correlation is supported by isobaric PDR models in the parameter space P_th/G_0 ~ [5e3-8e4] K/cm3 where many PDRs seem to lie. The CH+ (1-0) emission correlates with the extended emission from vibrationally excited H2, and with that of [CII]158um and CO 10-9, all emerging from FUV-irradiated gas. These correlations link the presence of CH+ to the availability of C+ ions and of FUV-pumped H2(v>0) molecules. The parsec-scale CH+ emission and narrow-line (dv ~ 3 km/s) mid-J CO emission arises from extended PDRs and not from fast shocks. PDR line tracers are the smoking gun of the stellar feedback from young massive stars. The PDR component in OMC-1 represents 5 to 10% of the total gas mass, however, it dominates the emitted line luminosity. These results provide insights into the source of submm CH+ and mid-J CO emission from distant star-forming galaxies.

arXiv commentAccepted for publication in Astronomy & Astrophysics (english not edited, abridged abstract, several figures have been bitmapped to lower quality)

References in corpus (57)

• Theory of Star Formation
• The Star Formation Rate and Dense Molecular Gas in Galaxies
• The distance to the Orion Nebula
• Far Infrared and Submillimeter Emission from Galactic and Extragalactic Photo-Dissociation Regions
• A model for atomic and molecular interstellar gas: The Meudon PDR code
• Rotational quenching of CO due to H${}_2$ collisions
• Water in Star-Forming Regions with the Herschel Space Observatory (WISH): Overview of key program and first results
• A multi-transition HCN and HCO+ study of 12 nearby active galaxies: AGN versus SB environments
• Morphology of the Interstellar Cooling Lines Detected by COBE
• A line confusion limited millimeter survey of Orion KL (I): sulfur carbon chains
• Dynamical Expansion of Ionization and Dissociation Front around a Massive Star. II. On the Generality of Triggered Star Formation
• Parametrization of C-shocks. Evolution of the Sputtering of Grains
• Molecular outflows in local ULIRGs: energetics from multi-transition OH analysis
• Models of turbulent dissipation regions in the diffuse interstellar medium
• On the Structure of the Orion A Cloud and the Formation of the Orion Nebula Cluster
• Interstellar Hydrides
• Compression and ablation of the photo-irradiated cloud the Orion Bar
• Winds and radiation in unison: a new semi-analytic feedback model for cloud dissolution
• Herschel observations of EXtra-Ordinary Sources: the present and future of spectral surveys with Herschel/HIFI
• Disruption of the Orion Molecular Core 1 by the stellar wind of the massive star ${\theta }^1$ Ori C
• Herschel/HIFI observations of [CII] and [13CII] in PDRs
• Velocity-resolved [CII] emission and [CII]/FIR Mapping along Orion with Herschel
• Gravitational collapse of the OMC-1 region
• The relative impact of photoionizing radiation and stellar winds on different environments
• The chemistry of ions in the Orion Bar I. - CH+, SH+, and CF+: The effect of high electron density and vibrationally excited H2 in a warm PDR surface
• Water cooling of shocks in protostellar outflows: Herschel-PACS map of L1157
• Structure of photodissociation fronts in star-forming regions revealed by observations of high-J CO emission lines with Herschel
• Surface chemistry in the Interstellar Medium II. ${\mathrm{H}}_2$ formation on dust with random temperature fluctuations
• [CII] absorption and emission in the diffuse interstellar medium across the Galactic Plane
• Hydrides in Young Stellar Objects: Radiation tracers in a protostar-disk-outflow system
• Orion's Bar: Physical Conditions across the Definitive H+ / H0 / H2 Interface
• Large turbulent reservoirs of cold molecular gas around high-redshift starburst galaxies
• Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk
• Water in star-forming regions with Herschel (WISH). IV. A survey of low-J H2O line profiles toward high-mass protostars
• Electron Excitation of High Dipole Moment Molecules Reexamined
• Herschel observations of the Sgr B2 cores: Hydrides, warm CO, and cold dust
• A complete model of CH+ rotational excitation including radiative and chemical pumping processes
• The three dimensional dynamic structure of the inner Orion Nebula
• Grain Destruction in Interstellar Shocks
• Water in star forming regions with Herschel (WISH) III. Far-infrared cooling lines in low-mass young stellar objects
• Herschel Far-Infrared Spectral-mapping of Orion BN/KL Outflows: Spatial distribution of excited CO, H2O, OH, O and C+ in shocked gas
• State-to-state chemistry and rotational excitation of CH${}^{+}$ in photon-dominated regions
• Origin of CH+ in diffuse molecular clouds warm H2 and ion-neutral drift
• Herschel HIFI observations of O${}_2$ toward Orion: special conditions for shock enhanced emission
• First detection of the Methylidyne cation (CH+) fundamental rotational line with the Herschel/SPIRE FTS
• Detection of HF emission from the Orion Bar
• Constraining physical conditions for the PDR of Trumpler 14 in the Carina Nebula
• WISH VI. Constraints on UV and X-ray irradiation from a survey of hydrides in low- to high-mass YSOs
• Effects of turbulent diffusion on the chemistry of diffuse clouds
• Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H2O and its isotopologues towards Orion KL
• Spatial distribution of FIR rotationally excited CH+ and OH emission lines in the Orion Bar PDR
• Herschel/HIFI Spectral Mapping of C${}^{+}$, CH${}^{+}$, and CH in Orion BN/KL: The Prevailing Role of Ultraviolet Irradiation in CH${}^{+}$ Formation
• A new mechanical stellar wind feedback model for the Rosette Nebula
• Kinematics of the ionized-to-neutral interfaces in Monoceros R2
• Analysis of the Herschel/HEXOS Spectral Survey Towards Orion South: A massive protostellar envelope with strong external irradiation
• A High Density Thin layer confining the HII region M42. HHT measurements
• CO Spectral Line Energy Distributions in Galactic Sources: Empirical Interpretation of Extragalactic Observations

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