Near-infrared emission of neutral carbon from photon-dominated regions

V. Escalante; A. Sternberg; A. Dalgarno

doi:10.1086/170225

Near-infrared emission of neutral carbon from photon-dominated regions

V. Escalante^*, A. Sternberg, A. Dalgarno

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

Detailed calculations are reported of the intensities of the near-infrared lines of neutral carbon atoms at λ = 985.0, 982.3, and 872.7 nm emitted from dense clouds subjected to intense radiation fields. There is a small contribution to the excitation of the metastable levels by electron impacts in the heated edge zones of the clouds but it is insignificant compared to that from the recombination of the C⁺ ions produced by photoionization. The lines observed in M42 and NGC 2024 can be interpreted as arising in gas with densities in excess of 10⁵ cm^-3 and radiation fields with intensities between 10³ and 10⁶ times the average interstellar field intensity. Radiative recombination of C⁺ ions may also be an important source of the emission lines detected in the planetary nebulae NGC 6270 and NGC 7027.

Original language	English
Pages (from-to)	630-634
Number of pages	5
Journal	Astrophysical Journal
Volume	375
Issue number	2
DOIs	https://doi.org/10.1086/170225
State	Published - 10 Jul 1991
Externally published	Yes

Keywords

Atomic processes
Infrared: spectra
Nebulae: H II regions
Nebulae: planetary

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10.1086/170225

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abstract = "Detailed calculations are reported of the intensities of the near-infrared lines of neutral carbon atoms at λ = 985.0, 982.3, and 872.7 nm emitted from dense clouds subjected to intense radiation fields. There is a small contribution to the excitation of the metastable levels by electron impacts in the heated edge zones of the clouds but it is insignificant compared to that from the recombination of the C+ ions produced by photoionization. The lines observed in M42 and NGC 2024 can be interpreted as arising in gas with densities in excess of 105 cm-3 and radiation fields with intensities between 103 and 106 times the average interstellar field intensity. Radiative recombination of C+ ions may also be an important source of the emission lines detected in the planetary nebulae NGC 6270 and NGC 7027.",

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T1 - Near-infrared emission of neutral carbon from photon-dominated regions

AU - Escalante, V.

AU - Sternberg, A.

AU - Dalgarno, A.

PY - 1991/7/10

Y1 - 1991/7/10

N2 - Detailed calculations are reported of the intensities of the near-infrared lines of neutral carbon atoms at λ = 985.0, 982.3, and 872.7 nm emitted from dense clouds subjected to intense radiation fields. There is a small contribution to the excitation of the metastable levels by electron impacts in the heated edge zones of the clouds but it is insignificant compared to that from the recombination of the C+ ions produced by photoionization. The lines observed in M42 and NGC 2024 can be interpreted as arising in gas with densities in excess of 105 cm-3 and radiation fields with intensities between 103 and 106 times the average interstellar field intensity. Radiative recombination of C+ ions may also be an important source of the emission lines detected in the planetary nebulae NGC 6270 and NGC 7027.

AB - Detailed calculations are reported of the intensities of the near-infrared lines of neutral carbon atoms at λ = 985.0, 982.3, and 872.7 nm emitted from dense clouds subjected to intense radiation fields. There is a small contribution to the excitation of the metastable levels by electron impacts in the heated edge zones of the clouds but it is insignificant compared to that from the recombination of the C+ ions produced by photoionization. The lines observed in M42 and NGC 2024 can be interpreted as arising in gas with densities in excess of 105 cm-3 and radiation fields with intensities between 103 and 106 times the average interstellar field intensity. Radiative recombination of C+ ions may also be an important source of the emission lines detected in the planetary nebulae NGC 6270 and NGC 7027.

KW - Atomic processes

KW - Infrared: spectra

KW - Nebulae: H II regions

KW - Nebulae: planetary

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Near-infrared emission of neutral carbon from photon-dominated regions

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Keywords

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