Magellanic Cloud Planetary Nebula with Suspected Strong Forbidden Iron Lines

The relatively high-excitation nebula (Westerlund-Smith object 25) in the large Magellanic cloud shows prominent forbidden lines of [Ar IV], the close [Ne IV] pair λ 4724, 4726, [Ca V] λ 5309, [Fe V] λ 4227, and probably [Fe VI] and [Fe VII], as well. A conventional interpretation of observations se...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 80; no. 6; pp. 1764 - 1766
Main Authors Aller, L. H., Czyzak, S. J.
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences of the United States of America 01.03.1983
National Acad Sciences
Subjects
Astronomical objects
Chemical composition
H II regions
Helium
Interstellar extinction
Ionization
Large Magellanic Cloud
Magellanic clouds
Physical Sciences: Astronomy
Planetary nebulae
Wavelengths
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Summary:The relatively high-excitation nebula (Westerlund-Smith object 25) in the large Magellanic cloud shows prominent forbidden lines of [Ar IV], the close [Ne IV] pair λ 4724, 4726, [Ca V] λ 5309, [Fe V] λ 4227, and probably [Fe VI] and [Fe VII], as well. A conventional interpretation of observations secured with a vidicon detector at the Cerro Tololo 4-m telescopes indicates an essentially ``normal'' helium abundance but depletions of N, O, Ne, and other elements with respect to our own galaxy. When a comparison is made with diffuse nebulae or H II regions in the large Magellanic cloud, we find helium to be more abundant, oxygen to be depleted, and nitrogen, neon, and argon to be comparable. The abundance of sulfur is uncertain. Iron in the gaseous phase is certainly more plentiful than in conventional planetaries.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.80.6.1764