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Third-dredge-up oxygen in planetary nebulae

D. Pequignot·J. R. Walsh·A. A. Zijlstra·G. Dudziak
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Abstract

The planetary nebulae He 2-436 and Wray 16-423 in the Sagittarius dwarf galaxy appear to result from nearly twin stars, except that third-dredge-up carbon is more abundant in He 2-436. A thorough photoionization-model analysis implies that ratios Ne/O, S/O and Ar/O are significantly smaller in He 2-436, indicative of third-dredge-up oxygen enrichment. The enrichment of oxygen with respect to carbon is (7 +/- 4)%. Excess nitrogen in Wray 16-423 suggests third dredge-up of late CN-cycle products even in these low-mass, intermediate-metallicity stars.

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D. Pequignot, J. R. Walsh, A. A. Zijlstra, G. Dudziak. 2000-08-29. Third-dredge-up oxygen in planetary nebulae. https://arxiv.org/abs/astro-ph/0008443

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