相关论文: Advances in s-process models

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…

We present nucleosynthesis predictions for massive (5-7 solar masses) asymptotic giant branch (AGB) stars of solar metallicity where we delay the onset of the superwind to pulsation periods of P =700-800 days. We found that delaying the…

We summarise the evolution and nucleosynthesis in AGB and Super-AGB stars. We then examine the major sources of uncertainty, especially mass-loss.

It is well appreciated that the description of overadiabatic convection affects the structure of the envelopes of luminous asymptotic giant branch (AGB) stars in the phase of ``hot bottom burning '' (HBB). We stress that this important…

The 13C(a, n)16O reaction is the major neutron source in low mass asymptotic giant branch (AGB) stars, where the main and the strong s process components are synthesised. After a third dredge-up (TDU) episode, 13C burns radiatively in a…

Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also…

We discuss the synthesis of some short-lived isotopes and of 23Na in thermally pulsing AGB stars with initial mass of 2 Msun and two different metallicities (Z=1.5e-2, corresponding to the metal amount in the Sun, and Z=1e-4),…

We outline a partial historical summary of the steps through which the nucleosynthesis phenomena induced by {\it slow} neutron captures (the {\it s-process}) were clarified, a scientific achievement in which Franz K\"appeler played a major…

The $s$-process nucleosynthesis in Asymptotic Giant Branch (AGB) stars depends on the modeling of convective boundaries. We present models and s-process simulations that adopt a treatment of convective boundaries based on the results of…

A major source of uncertainty in AGB models is the partial-mixing process of hydrogen, required for the formation of the so-called $^{13}$C pocket. Among the attempts to derive a self-consistent treatment of this physical process, there are…

The intermediate neutron-capture process (i-process) can occur during proton ingestion events (PIEs), which may take place in the early evolutionary phases of asymptotic giant branch (AGB) stars. We investigate the impact of rotational and…

The s-process in massive stars, producing nuclei up to $A\approx 90$, has a different behaviour at low metallicity if stellar rotation is significant. This enhanced s-process is distinct from the s-process in massive stars around solar…

In the course of a systematic exploration of the uncertainties associated to the input micro- and macro-physics in the modeling of the evolution of intermediate mass stars during their Asymptotic Giant Branch (AGB) phase, we focus on the…

The concept of overshoot has already been considered for numerous cases in stellar evolution calculations. We explore the consequences of overshoot at the convection zone which forms during the He-flash (thermal pulse) in AGB stars. We find…

S stars are transition objects between M-type giants and carbon stars on the asymptotic giant branch (AGB). They are characterized by overabundances of s-process elements. Roughly half of them are enhanced in technetium (Tc), an s-process…

The primary nature of the $^{13}$C neutron source is very significant for the studies of the s-process nucleosynthesis. In this paper we present an attempt to fit the element abundances observed in 16 s-rich stars using parametric model of…

We present computations of nucleosynthesis in low-mass red-giant-branch and asymptotic-giant-branch stars of Population I experiencing extended mixing. We adopt the updated version of the FRANEC evolutionary model, a new post-process code…

A systematic investigation on the third dredge up in a 3M$_{\odot}$, solar metallicity AGB star will be presented. The model evolves from the main sequence up to the Asymptotic Giant Branch (AGB). Intermediate mass stars are important…

The observational data guiding the theoretical chemical evolutionary models of AGB stars come mainly from the analysis of intrinsic and extrinsic s-process enriched objects. The first are the stars of the M-MS-S-SC-C star sequence which is…

Barium (Ba) stars are polluted by material enriched in the slow neutron capture (s-process) elements synthesised in the interior of their former asymptotic giant branch (AGB) companion star, which is now a white dwarf. We compare individual…