The Structure of the Orion Nebula. I. Observations of the C 85a Recombination Line

Balick, Bruce; Gammon, Richard H.; Doherty, L. H.

doi:10.1086/152683

Cited by 17 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The residuals shown in Figures 4 and 5 show the levels where the approximations fail, typically at the 2%-4% level of peak intensity near line center. The residuals are non-Gaussian (and thus cannot be minimized further with an arbitrary increase in the number of Gaussian fit components), and widths of the residual features are ≈1-2 km s Balick et al (1974), who suggested a dynamically distinct and quiescent cloud interface between OrionKL and the Trapezium stars, compared to the HII emitting region.…”

Section: Properties Of the C + Gasmentioning

confidence: 99%

HERSCHEL/HIFI SPECTRAL MAPPING OF C⁺, CH⁺, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH⁺ FORMATION

Morris

Gupta

Nagy

et al. 2016

ApJ

View full text Add to dashboard Cite

The CH + ion is a key species in the initial steps of interstellar carbon chemistry. Its formation in diverse environments where it is observed is not well understood, however, because the main production pathway is so endothermic (4280 K) that it is unlikely to proceed at the typical temperatures of molecular clouds. We investigate the formation of this highly reactive molecule with the first velocity-resolved spectral mapping of the CH + J= 1−0, 2−1 rotational transitions, three sets of CH Λ-doubled triplet lines, 12 C + and 13 C + P P , and CH is indicated to arise in the diluted gas, outside the explosive, dense BN/KL outflow. Our models show that UV irradiation provides favorable conditions for steady-state production of CH + in this environment. Surprisingly, no spatial or kinematic correspondences of the observed species are found with H 2 S(1) emission tracing shocked gas in the outflow. We propose that C + is being consumed by rapid production of CO to explain the lack of both C + and CH + in the outflow. Hence, in star-forming environments containing sources of shocks and strong UV radiation, a description of the conditions leading to CH + formation and excitation is incomplete without including the important-possibly dominant-role of UV irradiation.

show abstract

Section: Properties Of the C + Gasmentioning

confidence: 99%

HERSCHEL/HIFI SPECTRAL MAPPING OF C⁺, CH⁺, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH⁺ FORMATION

Morris

Gupta

Nagy

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…Observations of CI recombination lines date back two decades (Balick et al, 1974;Knapp et al, 1976aKnapp et al, , 1976bPankonin et al, 1977;Jaffe and Pankonin, 1978;Pankonin and Walmsley, 1978) but only in recent years have their importance for the study of PDRs been fully realized (Natta et al, 1994;Wyrowski, Schilke, et al, 1997;Wyroski, Walmsley, et al, 1997). Observations show that the CI radio recombination lines also form in PDRs (Fig.…”

Section: E CI Recombination Linesmentioning

confidence: 99%

Photodissociation regions in the interstellar medium of galaxies

Hollenbach

Tielens²

1999

Rev. Mod. Phys.

756

712

View full text Add to dashboard Cite

The interstellar medium of galaxies is the reservoir out of which stars are born and into which stars inject newly created elements as they age. The physical properties of the interstellar medium are governed in part by the radiation emitted by these stars. Far-ultraviolet (6 eVϽh Ͻ13.6 eV) photons from massive stars dominate the heating and influence the chemistry of the neutral atomic gas and much of the molecular gas in galaxies. Predominantly neutral regions of the interstellar medium in which the heating and chemistry are regulated by far ultraviolet photons are termed PhotoDissociation Regions (PDRs). These regions are the origin of most of the non-stellar infrared (IR) and the millimeter and submillimeter CO emission from galaxies. The importance of PDRs has become increasingly apparent with advances in IR and submillimeter astronomy. The IR emission from PDRs includes fine structure lines of C, C ϩ , and O; rovibrational lines of H 2 ; rotational lines of CO; broad mid-IR features of polycyclic aromatic hydrocarbons; and a luminous underlying IR continuum from interstellar dust. The transition of H to H 2 and C ϩ to CO occurs within PDRs. Comparison of observations with theoretical models of PDRs enables one to determine the density and temperature structure, the elemental abundances, the level of ionization, and the radiation field. PDR models have been applied to interstellar clouds near massive stars, planetary nebulae, red giant outflows, photoevaporating planetary disks around newly formed stars, diffuse clouds, the neutral intercloud medium, and molecular clouds in the interstellar radiation field-in summary, much of the interstellar medium in galaxies. Theoretical PDR models explain the observed correlations of the [CII] 158 m with the CO Jϭ1 -0 emission, the CO Jϭ1 -0 luminosity with the interstellar molecular mass, and the [CII] 158 m plus [OI] 63 m luminosity with the IR continuum luminosity. On a more global scale, PDR models predict the existence of two stable neutral phases of the interstellar medium, elucidate the formation and destruction of star-forming molecular clouds, and suggest radiation-induced feedback mechanisms that may regulate star formation rates and the column density of gas through giant molecular clouds. [S0034-6861(99)01001-6] CONTENTS

show abstract

“…In another study [47], he investigated the polarization of C iv emission lines in the spectra of planetary nebulae. Investigating the structure of the Orion Nebula and the surrounding neutral medium, Balick et al [48] mapped the recombination line C 85α of carbon using high spatial resolution all over the nebula to determine the ionized carbon distribution and its relationship to the H ii region.…”

Section: Recombination Lines Of Carbonmentioning

confidence: 99%

Atomic and Molecular Aspects of Astronomical Spectra

Sochi

2012

Preprint

View full text Add to dashboard Cite

In the first section of this thesis, we present the atomic part of our investigation.A C 2+ atomic target was prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. The R-matrix method of electron scattering theory was used to describe the C 2+ plus electron system. Theoretical data concerning bound and autoionizing states were generated in the intermediate-coupling approximation by R-matrix and Autostructure codes and compared to experimental data. The comparison revealed very good agreement. These theoretical data were then used to generate dielectronic recombination data for C + which include transition lines, oscillator strengths, radiative transition probabilities, as well as emissivity and dielectronic recombination coefficients. The data were cast in the form of a line list, called SS1, containing 6187 optically-allowed transitions which include many C ii lines observed in astronomical spectra. The data were validated by comparison to C + recombination data obtained from a number of sources in the literature. This line list was used to analyze the spectra from a number of astronomical objects, mainly planetary nebulae, and identify their electron temperature where the observational data were obtained from the literature. The electron temperature investigation was also extended to include free electron energy analysis which uses observational and theoretical data of FF and FB transitions to investigate the long-standing problem of discrepancy between the results of recombination and forbidden lines analysis and its possible connection to the electron distribution (Maxwellian or non-Maxwellian).

show abstract

The Structure of the Orion Nebula. I. Observations of the C 85a Recombination Line

Cited by 17 publications

References 0 publications

HERSCHEL/HIFI SPECTRAL MAPPING OF C⁺, CH⁺, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH⁺ FORMATION

HERSCHEL/HIFI SPECTRAL MAPPING OF C⁺, CH⁺, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH⁺ FORMATION

Photodissociation regions in the interstellar medium of galaxies

Atomic and Molecular Aspects of Astronomical Spectra

Contact Info

Product

Resources

About

The Structure of the Orion Nebula. I. Observations of the C 85a Recombination Line

Cited by 17 publications

References 0 publications

HERSCHEL/HIFI SPECTRAL MAPPING OF C+, CH+, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH+ FORMATION

HERSCHEL/HIFI SPECTRAL MAPPING OF C+, CH+, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH+ FORMATION

Photodissociation regions in the interstellar medium of galaxies

Atomic and Molecular Aspects of Astronomical Spectra

Contact Info

Product

Resources

About

HERSCHEL/HIFI SPECTRAL MAPPING OF C⁺, CH⁺, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH⁺ FORMATION

HERSCHEL/HIFI SPECTRAL MAPPING OF C⁺, CH⁺, AND CH IN ORION BN/KL: THE PREVAILING ROLE OF ULTRAVIOLET IRRADIATION IN CH⁺ FORMATION