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Near Infrared Emission of Neutral Carbon from Photon-Dominated Regions

Published online by Cambridge University Press:  07 August 2017

V. Escalante ,
A. Sternberg  and
A. Dalgarno
V. Escalante
Affiliation:
Instituto de Astronomía, UNAM, Ap. Postal 70-264, Mexico, DF 04510, Mexico
A. Sternberg
Affiliation:
School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Israel
A. Dalgarno
Affiliation:
Center for Astrophysics, 60 Garden St. Cambridge, MA 02138, USA

Abstract

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Detailed calculations are reported of the intensities of the near infrared forbidden lines of neutral carbon atoms at λ 985.0 nm, 982.3 nm and 872.7 nm emitted from dense clouds subjected to intense radiation fields. The metastable levels that produce the lines are excited by radiative recombination of the C+ ions produced by photoionization. Impacts of electrons with C atoms in the heated edge zones of the clouds contribute an insignificant part to the excitation. 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.

Type
Chemistry of Interface Regions
Information
Symposium - International Astronomical Union , Volume 150: Astrochemistry of Cosmic Phenomena , 1992 , pp. 333 - 334
Copyright
Copyright © Kluwer 1992 

References

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