Third-dredge-up oxygen in planetary nebulae

D. Pequignot, J.R. Walsh, A.A. Zijlstra, G. Dudziak

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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 inWray 16-423 suggests third dredge-up of late-CN-cycle products even in these low-mass, intermediate-metallicity stars.
Original languageEnglish
Pages (from-to)L1-L4
Number of pages4
JournalAstronomy and Astrophysics
Issue number1
Publication statusPublished - Sep 2000



  • nuclear reactions
  • nucleosynthesis
  • planetary nebulae
  • galaxies
  • Sagittarius
  • stars

Cite this

Pequignot, D., Walsh, J. R., Zijlstra, A. A., & Dudziak, G. (2000). Third-dredge-up oxygen in planetary nebulae. Astronomy and Astrophysics, 361(1), L1-L4.