Related papers: Uncertainties in AGB Evolution and Nucleosynthesis
The winds observed around asymptotic giant branch (AGB) stars are generally attributed to radiation pressure on dust, which is formed in the extended dynamical atmospheres of these pulsating, strongly convective stars. Current…
(abridged) Observations clearly show that low-mass AGB stars can provide a nucleosynthesis site of the s-process. Recent stellar evolution models indicate that radiative burning of C13 between thermal pulses in low-mass AGB stars may indeed…
A Monte Carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal-poor globular clusters has been conducted. Confidence limits are derived on the absolute V-band magnitude of the bump in…
It is now about 30 years ago that photometric and spectroscopic surveys of asymptotic giant branch (AGB) stars in the Magellanic Clouds (MCs) uncovered the first examples of truly massive (> 3-4 M_s) O-rich AGB stars experiencing hot bottom…
A brief overview of non-standard big bang nucleosynthesis (BBN) scenarios is presented. Trends and results of the light-element nucleosynthesis in BBN scenarios with small-scale or large-scale inhomogeneity, the presence of antimatter…
The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity…
Several recent spectroscopic investigations have presented conflicting results on the existence of Na-rich asymptotic giant branch (AGB) stars in the Galactic globular cluster M4 (NGC6121). The studies disagree on whether or not Na-rich red…
Although the detailed conditions for explosive nucleosynthesis are derived from astrophysical modeling, nuclear physics determines fundamental patterns in abundance yields, not only for equilibrium processes. Focussing on the nu-p- and the…
Variability studies hold information on otherwise unresolvable regions in Active Galactic Nuclei (AGN). Population studies of large samples likewise have been very productive for our understanding of AGN. These two themes are coming…
We present a brief review of Big Bang Nucleosynthesis (BBN). We discuss theoretical and observational uncertainties in deuterium and helium-4 primordial abundances and their implications for the determination of important cosmological…
We summarize the history, theory, observational status, and implications of big-bang nucleosynthesis.
This contribution reviews recent observational results concerning astronomical masers toward post-AGB objects with a special attention to water fountain sources and the prototypical source OH231.8+4.2. These sources represent a short…
An analysis of high-resolution near-infrared spectra of a sample of 45 asymptotic giant branch (AGB) stars towards the Galactic bulge is presented. The sample consists of two subsamples, a larger one in the inner and intermediate bulge, and…
We present a novel approach to address dust production by low- and intermediate-mass stars. We study the asymptotic giant branch (AGB) phase, during which the formation of dust takes place, from the perspective of post-AGB and planetary…
We are currently studying carbon based dust types of relevance for carbon-rich AGB stars, to obtain a better understanding of the influence of the optical and chemical properties of the grains on the mass loss of the star. An investigation…
I will briefly review the state of the art of evolutionary population synthesis (EPS) models that include the contribution from AGB stars.
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…
There have been a number of important recent developments in theoretical and observational studies of nucleosynthesis, especially regarding nucleosynthetic sources at low metallicities. Those selected for discussion here include the origin…
Recent surveys confirm early results about a deficiency or even absence of CN-strong stars on the asymptotic giant branch (AGB) of globular clusters (GCs), although with quite large cluster-to-cluster variations. In general, this is at odds…
We investigated the impact of uncertainties in neutron-capture and weak reactions (on heavy elements) on the s-process nucleosynthesis in low-mass stars and massive stars using a Monte-Carlo based approach. We performed extensive nuclear…