Third-dredge-up oxygen in planetary nebulae
Astrophysics
2007-05-23 v1
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.
Keywords
Cite
@article{arxiv.astro-ph/0008443,
title = {Third-dredge-up oxygen in planetary nebulae},
author = {D. Pequignot and J. R. Walsh and A. A. Zijlstra and G. Dudziak},
journal= {arXiv preprint arXiv:astro-ph/0008443},
year = {2007}
}
Comments
To appear in Astron. Astrophys. Lett. (Latex, 5 pages, 1 postscript figure)