Magellanic cloud planetary nebula with suspected strong forbidden iron lines

AUTOR(ES)

Aller, L. H.

RESUMO

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 λ4724, 4726, [Ca V] λ5309, [Fe V] λ4227, 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.

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