Determination of N/O from far-infrared line observations of Galactic H II regions

Measurements of the 52- and 88-micron forbidden O III line ratios and the 57-micron forbidden N III line ratio for six H II regions have been obtained with the NASA Kuiper Airborne Observatory. The derived N/O ratio for most Galactic regions (of about 0.2-0.3) is greater than that obtained by optica...

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Bibliographic Details
Published inThe Astrophysical journal Vol. 327; no. 1; pp. 377 - 388
Main Authors Rubin, R. H., Simpson, J. P., Erickson, E. F., Haas, M. R.
Format Journal Article
LanguageEnglish
Published Legacy CDMS University of Chicago Press 01.04.1988
Subjects
Astronomy
Astrophysics
Earth, ocean, space
Exact sciences and technology
H ii regions. Emission and reflection nebulae
Interstellar medium (ism) and nebulae in milky way
Stellar systems. Galactic and extragalactic objects and systems. The universe
Grating spectrometer
Abundance
Abundance ratio
H II region
Gaseous nebula
Far infrared spectrum
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Summary:Measurements of the 52- and 88-micron forbidden O III line ratios and the 57-micron forbidden N III line ratio for six H II regions have been obtained with the NASA Kuiper Airborne Observatory. The derived N/O ratio for most Galactic regions (of about 0.2-0.3) is greater than that obtained by optical studies, and it exceeds the solar value. Although enhancement of N/O at a galactocentric distance of about 6 kpc may be possible, no evidence is found for an overall linear gradient in N/O with galactocentric distance, suggesting that N-14 is predominantly produced by primary rather than secondary nucleosynthesis.
Bibliography:CDMS
Legacy CDMS
ISSN:0004-637X
1538-4357
DOI:10.1086/166200