Related papers: The s-process in rotating AGB stars
Barium (Ba) stars help to verify asymptotic giant branch (AGB) star nucleosynthesis models since they experienced pollution from an AGB binary companion and thus their spectra carry the signatures of the slow neutron capture process (s…
The stars in globular clusters are known to differ in their surface chemistry: the spectroscopic investigations in the last decades outlined the presence of star-to-star differences in the abundances of the light elements, up to aluminium…
It is known that there must be some weak form of transport (called cool bottom processing, or CBP) acting in low mass RGB and AGB stars, adding nuclei, newly produced near the hydrogen-burning shell, to the convective envelope. We assume…
The results of our second stage (1998-2018) of the detailed spectroscopy of peculiar supergiants identified with galactic infrared sources, performed mainly at the 6-meter BTA telescope are summarized. The main aspect of the program is a…
An updated grid of stellar yields for low to intermediate-mass thermally-pulsing Asymptotic Giant Branch (AGB) stars are presented. The models cover a range in metallicity Z = 0.02, 0.008, 0.004, and 0.0001, and masses between 1Msun to…
We present here the application of a model for a mass circulation mechanism in between the H-burning shell and the base of the convective envelope of low mass AGB stars, aimed at studying the isotopic composition of those presolar grains…
In this paper we analyze the effects induced by rotation on low mass Asymptotic Giant Branch stars. We compute two sets of models, M=2.0 Msun at [Fe/H]=0 and M=1.5 Msun at [Fe/H]=-1.7, respectively, by adopting Main Sequence rotation…
During most of their life, stars fuse hydrogen into helium in their cores. The mixing of chemical elements in the radiative envelope of stars with a convective core is able to replenish the core with extra fuel. If effective, such deep…
Many observational results seem to indicate more efficient mixing processes in intermediate mass stars (5-20 M$_{\odot}$) than the expected by the standard models. These processes are usually thought to be caused by stellar rotation. Our…
Lithium is made up in the envelopes of massive Asymptotic Giant Branch (AGB) stars through the process of Hot Bottom Burning. In Globular Clusters, this processing is one possible source of the hot-CNO burning whose nuclear products are…
Long expected transition states between the rotation powered and accretion powered non-thermal emission in the millisecond pulsar binary systems have been recently observed in the case of three objects PSR J1023+0038, PSR J1824-2452, and…
We present full stellar evolution and parametric models of the surface abundance evolution of O16, Ne22, Na23 and the magnesium isotopes in an extremely metal-poor intermediate mass star M_ZAMS=5M_sun, Z=0.0001. O16 and Ne22 are injected…
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…
Context: Intermediate-mass asymptotic giant branch (AGB) stars influence Galactic lithium evolution by ejecting surface material (including Li) via stellar winds. Internal gravity waves (IGW), excited by convective motions, drive turbulent…
During the asymptoyic giant branch (AGB) phase, different elements are dredge-up to the stellar surface depending on progenitor mass and metallicity. When the mass loss increases at the end of the AGB, a circumstellar dust shell is formed,…
(abridged) Numerous spectroscopic observations provide compelling evidence for non-canonical processes that modify the surface abundances of low- and intermediate-mass stars beyond the predictions of standard stellar theory. We study the…
A self-consistent model of the chemical evolution of the globular cluster NGC 6752 is presented to test a popular theory that observed abundance anomalies are due to ``internal pollution'' from intermediate mass asymptotic giant branch…
The chemical compositions of the C-rich pAGB stars IRAS 05113+1347 and IRAS 22272+5424 are determined from high-resolution optical spectra using standard LTE model atmosphere-based techniques. The stars are C, N, and $s$-process enriched…
It is demonstrated that deep circulation mixing below the base of the standard convective envelope, and the consequent "cool bottom processing" (CBP) of the CNO isotopes, can reproduce the trend with stellar mass of the C-12/C-13…
Convection in the cores of massive stars becomes anisotropic when they rotate. This anisotropy leads to a misalignment of the thermal gradient and the thermal flux, which in turn results in baroclinicity and circulation currents in the…