相关论文: Carbon Stars and Nucleosynthesis in Galaxies

A chemical study of normal Galactic C(N) carbon stars is presented. Abundances of Li, CNO isotopes and s-elements are derived. The derived abundances of s-elements nicely agree with theoretical s-process nucleosynthesis predictions during…

Carbon (C) is thought to be produced by both core collapse supernovae (CCSN) and asymptotic giant branch (AGB) stars, but the relative contributions of these two sources are uncertain. We investigate the astrophysical origin of C using…

Asymptotic Giant Branch (AGB) stars are important players in the chemical evolution modelling of galaxies, because they are major producers of several chemical elements and excellent tracers of the structure and of the star formation…

An analysis of the fluorine abundance in Galactic AGB carbon stars (24 N-type, 5 SC-type and 5 J-type) is presented. This study uses the state- of-the-art carbon rich atmosphere models and improved atomic and molecular line lists in the 2.3…

The determinations of element abundances in red-giant stars and in particular in AGB stars are reviewed and the resulting abundances are compared with those obtained for planetary nebulae in the Galaxy and in nearby galaxies. The problems,…

Using the standard infall model of Galactic chemical evolution, we explore the origin of carbon and calculate the abundance evolution of CNO elements for 8 different models of stellar nucleosynthesis yields. The results show that, in the…

Oxygen and carbon-rich AGB stars - and objects directly polluted by them - are excellent laboratories to investigate the nucleosynthesis and mixing processes occurring during the later phases of the of low- and intermediate-mass star…

Our current knowledge of carbon stars in the Local Group and beyond, is discussed. Although many carbon stars and late M-stars have been identified in external galaxies a coherent understanding in terms of the chemical evolution- and star…

AGB stars are responsible for producing a variety of elements, including carbon, nitrogen, and the heavy elements produced in the slow neutron-capture process ($s$-elements). There are many uncertainties involved in modelling the evolution…

Emission and absorption line observations of molecules in late-type stars are a vital component in our understanding of stellar evolution, dust formation and mass loss in these objects. The molecular composition of the gas in the…

Most stars in our Galaxy with photospheric C/O>1 (carbon stars) are not giants but dwarfs. The newly-recognized class of dwarf carbon (dC) stars joins the growing family of stars with peculiar abundances that are now recognized as products…

Abundances of Li, heavy elements and carbon isotope ratios have been measured 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…

We employ analytical and numerical chemical evolution models to study observed trends in abundance ratios involving carbon, nitrogen, and oxygen. Several sets of published stellar yields for both intermediate-mass and massive stars are…

Although carbon is, together with oxygen and nitrogen, one of the most important elements in the study of galactic chemical evolution its production sites are still poorly known and have been much debated (see e.g. Gustafsson et al. 1999;…

Revised spectroscopic parameters for the HF molecule and a new CN line list in the 2.3 mu region have been recently available, allowing a revision of the F content in AGB stars. AGB carbon stars are the only observationally confirmed…

The trends of chemical abundances and abundance ratios observed in stars of different ages, kinematics, and metallicities bear the imprints of several physical processes that concur to shape the host galaxy properties. By inspecting these…

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…

Context. Carbon, nitrogen, and oxygen are the most abundant elements throughout the universe, after hydrogen and helium. Studying these elements in low-metallicity stars can provide crucial information on the chemical composition in the…

It is now clear that abundance variations from star-to-star among the light elements, particularly C, N, O, Na and Al, are ubiquitous within galactic globular clusters; they appear seen whenever data of high quality is obtained for a…

Planetary nebulae retain the signature of the nucleosynthesis and mixing events that occurred during the previous AGB phase. Observational signatures complement observations of AGB and post-AGB stars and their binary companions. The…