相关论文: Probing O-enrichment in C-rich dust planetary nebu…
We present nucleosynthesis predictions (HeCNOCl) from asymptotic giant branch (AGB) models, with diffusive overshooting from all the convective borders, in the metallicity range Z/4 < Z < 2Zsun. They are compared to recent precise nebular…
We previously determined abundances of He, C, N, O, and Ne for a sample of planetary nebulae (PNe) representing a broad range in progenitor mass and metallicity, and we now compare them with theoretical predictions of PNe abundances from a…
The determination of heavy element abundances from planetary nebula (PN) spectra provides an exciting opportunity to study the nucleosynthesis occurring in the progenitor asymptotic giant branch (AGB) star. We perform post-processing…
We study the relation between the chemical composition and the type of dust present in a group of 20 Galactic planetary nebulae (PNe) that have high quality optical and infrared spectra. The optical spectra are used, together with the best…
This paper summarizes a project designed to study abundances in a sample of planetary nebulae representing a broad range in progenitor mass and metallicity. We collect abundances of C, N, and O determined for the entire sample and compare…
We explore the elemental abundances in Galactic planetary nebulae (PNe) compared with those of their stellar progenitors (Red Giant Branch and Asymptotic Giant Branch, RGB and AGB, stars), to explore and quantify the expected -- i.e., due…
A project which aims to understand the abundance patterns of He, C, N, O, Ne, S, and Ar for a small sample of planetary nebulae is described. Abundance ratios of O/H, C/O, and N/O especially show a broad range relative to their solar…
We study the chemical abundances of a wide sample of 142 Galactic planetary nebulae (PNe) with good quality observations, for which the abundances have been derived more or less homogeneously, thus allowing a reasonable comparison with…
The iron depletion factors found in Galactic planetary nebulae (PNe) span over two orders of magnitude, suggesting that there are differences in the grain formation and destruction processes from object to object. We explore here the…
Our understanding of the chemical evolution of the Galactic bulge requires the determination of abundances in large samples of giant stars and planetary nebulae (PNe). We discuss PNe abundances in the Galactic bulge and compare these…
We analyse the planetary nebulae (PNe) population of the Small Magellanic Cloud (SMC), based on evolutionary models of stars with metallicities in the range $10^{-3} \leq Z \leq 4\times 10^{-3}$ and mass $0.9 M\odot < M < 8M\odot$, evolved…
The elemental abundances of ten planetary nebulae, derived with high accuracy including ISO and IUE spectra, are analysed with the aid of synthetic evolutionary models for the TP-AGB phase. Model prescriptions are varied until we achieve…
Planetary Nebulae (PNe) abundance patterns have long been used to note signatures of nuclear processing and to trace the distribution of metals throughout galaxies. We present abundance gradients and heavy element ratios based upon newly…
The primary goal of this paper is to make a direct comparison between the measured and model-predicted abundances of He, C and N in a sample of 35 well-observed Galactic planetary nebulae (PN). All observations, data reductions, and…
We constrain the iron abundance in a sample of 33 low-ionization Galactic planetary nebulae (PNe) using [Fe III] lines and correcting for the contribution of higher ionization states with ionization correction factors (ICFs) that take into…
We have obtained deep optical spectrophotometry of 16 planetary nebulae in M33, mostly located in the central two kpc of the galaxy, with the Subaru and Keck telescopes. We have derived electron temperatures and chemical abundances from the…
We present new low-resolution (R~800) optical spectra of 22 Galactic PNe with Spitzer spectra. These data are combined with recent optical spectroscopic data available in the literature to construct representative samples of compact (and…
We present an analysis of elemental abundances of He, N, O, Ne, S, and Ar in Magellanic Cloud planetary nebulae (PNe), and focus initially on 14 PNe in the Small Magellanic Cloud (SMC). We derived the abundances from a combination of deep,…
The concomitant overabundances of C, N and s-process elements are commonly ascribed to the complex interplay of nucleosynthesis, mixing and mass loss taking place in Asymptotic Giant Branch stars. At low metallicity, the enhancement of C…
We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample…