NEAR-INFRARED EMISSION OF NEUTRAL CARBON FROM PHOTON-DOMINATED REGIONS

被引：30

作者：

ESCALANTE, V

STERNBERG, A

DALGARNO, A

机构：

[1] MAX PLANCK INST PHYS & ASTROPHYS,INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY

[2] HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138

来源：

ASTROPHYSICAL JOURNAL | 1991年 / 375卷 / 02期

关键词：

ATOMIC PROCESSES; INFRARED; SPECTRA; NEBULAE; H-II REGIONS; PLANETARY;

D O I：

10.1086/170225

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Detailed calculations are reported of the intensities of the near-infrared lines of neutral carbon atoms at lambda = 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 10(5) cm-3 and radiation fields with intensities between 10(3) and 10(6) 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.

引用

页码：630 / 634

页数：5

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