Bibcode
García-Hernández, D. A.; Ventura, P.; Delgado-Inglada, G.; Dell'Agli, F.; Di Criscienzo, M.; Yagüe, A.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society: Letters, Volume 458, Issue 1, p.118-122
Advertised on:
5
2016
Citations
15
Refereed citations
14
Description
The abundance of O in planetary nebulae (PNe) has been historically used
as a metallicity indicator of the interstellar medium (ISM), where they
originated; e.g. it has been widely used to study metallicity gradients
in our Galaxy and beyond. However, clear observational evidence for O
self-enrichment in low-metallicity Galactic PNe with C-rich dust has
been recently reported. Here, we report asymptotic giant branch (AGB)
nucleosynthesis predictions for the abundances of the CNO elements and
helium in the metallicity range Z⊙/4 < Z < 2
Z⊙. Our AGB models, with diffusive overshooting from all
the convective borders, predict that O is overproduced in low-Z low-mass
(˜1-3 M⊙) AGB stars and nicely reproduce the recent
O overabundances observed in C-rich dust PNe. This confirms that O is
not always a good proxy of the original ISM metallicity and other
chemical elements such as Cl or Ar should be used instead. The
production of oxygen by low-mass stars should be thus considered in
galactic-evolution models.