Related papers: Fluorine Abundances in Galactic AGB Stars
In the light of the new observational data related to fluorine abundances in the solar neighborhood stars, we present here chemical evolution models testing different fluorine nucleosynthesis prescriptions with the aim to best fit those new…
The majority of the inhomogeneities in the chemical composition of Globular Cluster (GC) stars appear due to primordial enrichment. The most studied model today claims that the ejecta of Asymptotic Giant Branch (AGB) stars of high mass…
We consider the formation of dwarf carbon stars via accretion from a carbon AGB companion in light of the new 107 object sample of Downes et al. (2004). This sample is now large enough to allow good mass determination via comparison of a…
Context: This paper is part of a larger project in which we study the chemical abundances of extra-galactic post-AGB stars with the ultimate goal of improving our knowledge of the poorly understood AGB third dredge-up mixing processes and…
Aim: We aim to determine the abundances of CS, SiO, and SiS in a large sample of carbon star envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in…
The Galactic Centre (GC) has experienced a high degree of recent star-forming activity, as evidenced by the large number of massive stars currently residing there. The relative abundances of chemical elements in the GC may provide insights…
Barium stars are one of the important probes to understand the origin and evolution of slow neutron-capture process elements in the Galaxy. These are extrinsic stars, where the observed s-process element abundances are believed to have an…
We previously explored the circumstellar effects on the Rb and Zr abundances in massive Galactic O-rich AGB stars. Here we are interested in the role of the extended atmosphere in the case of Li and Ca. Li is an important indicator of HBB…
The cosmic origin of fluorine is still not well constrained. Several nucleosynthetic channels at different phases of stellar evolution have been suggested, but these must be constrained by observations. For this, the fluorine abundance…
This paper is the first of a series specifically studying the abundances of sulfur, chlorine, and argon in Type II planetary nebulae (PNe) in the Galactic disk. Ratios of S/O, Cl/O, and Ar/O constitute important tests of differential…
We analyze a set of published elemental abundances from a sample of CH stars which are based on high resolution spectral analysis of ELODIE and SUBARU/HDS spectra. All the elemental abundances were derived from local thermodynamic…
We present an analysis and comparison of the 30 micron dust features seen in the Spitzer Space Telescope spectra of 207 carbon-rich asymptotic giant branch (AGB) stars, post-AGB objects, and planetary nebulae located in the Milky Way, the…
A review is presented of the most relevant results obtained in the last few years on this rare class of astronomical sources. Multi-wavelength analysis of an increasing number of post-AGB stars reveal that they constitute a more…
Multiple stellar populations (MPs) are a distinct characteristic of Globular Clusters (GCs). Their general properties have been widely studied among main sequence, red giant branch (RGB) and horizontal branch (HB) stars, but a common…
We present a diagnostic tool to determine the forsterite abundance of the dust ejected by AGB stars. Our method is based on a comparison between the observed strength of spectral bands of forsterite and model calculations. We show that the…
The bulge carbon stars have been a mystery since their discovery, because they are about 2.5mag too faint to be regarded as genuine AGB stars, if located inside the metal-rich bulge (m-M=14.5mag). Part of the mystery can be solved if these…
Carbon and oxygen abundances in F and G main-sequence stars ranging in metallicity from [Fe/H] = -1.6 to +0.5 are determined from a non-LTE analysis of CI and OI atomic lines in high-resolution spectra. Both C and O are good tracers of…
This paper is the fourth and final report on a project designed to study carbon abundances in a sample of planetary nebulae representing a broad range in progenitor mass and metallicity. We present newly acquired optical spectrophotometric…
High-resolution spectra of 13 core helium-burning stars in the thick disk of the Galaxy have been obtained with the SOFIN spectrograph on the Nordic Optical Telescope to investigate abundances of up to 22 chemical elements. Abundances of…
Abundances of lithium, heavy elements and carbon isotope ratios have been derived in 12 J-type galactic carbon stars. The abundance analysis shows that in these stars the abundances of s-process elements with respect to the metallicity are…