Related papers: Stellar Evolution Constraints on the Triple-Alpha …
We discuss the influence of the 12C(alpha,gamma)16O$ reaction rate on the central He burning of stars in the mass range 0.8-25 Msun, as well as its effects on the explosive yields of a 25 Msun star of solar chemical composition. We find…
Background: The triple-alpha reaction is the key to our understanding about the nucleosynthesis and the observed abundance of $^{12}$C in stars. The theory of this process is well established at high temperatures but rather ambiguous in the…
Motivated by the possible existence of other universes, this paper considers the evolution of massive stars with different values for the fundamental constants. We focus on variations in the triple alpha resonance energy and study its…
Helium burning is one of the most fundamental steps of stellar nucleosynthesis, as it describes the formation of life-determining element of carbon, while it plays a key role in the evolution of Red Giant, accreting White Dwarfs and Neutron…
Modeling of the stars in the red clump (RC) is challenging, due to the uncertainties associated with the physical processes happening in their core and during the helium flash. By probing the internal stellar structure, asteroseismology…
We propose a temperature-resolved Monte Carlo (MC) approach to identify the temperature regimes in which low-energy helium-burning reaction rates most strongly affect nucleosynthesis in very massive stars that undergo pair-instability…
A new full three-body method is introduced to compute the rate of the triple-alpha capture reaction which is the primary source of $^{12}$C in stars. In this work, we combine the Faddeev hyperspherical harmonics and the R-matrix method to…
We have investigated the impact of the $^{14}N(p,\gamma)^{15}O$ reaction rate recently redetermined by the LUNA experiment, on the shell H-burning and core He-burning phases of low-mass, metal poor stellar models. The new reaction rate has…
Effects of a new triple-{\alpha} reaction rate on the s-process during the evolution of a massive star of 25 M\odot are investigated for the first time. Although the s-process in massive stars has been believed to be established with only…
The nuclear rates for reactions involving 12C and 16O are key to compute the energy release and nucleosynthesis of massive stars during their evolution. These rates shape the stellar structure and evolution, and impact the nature of the…
[Shortened] The 12C + 12C fusion reaction has been the subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. In order to investigate the effect of an enhanced carbon…
The thermonuclear $^{19}$F($p$,$\alpha_0$)$^{16}$O reaction rate in a temperature region of 0.007--10 GK has been derived by re-evaluating the available experimental data, together with the low-energy theoretical $R$-matrix extrapolations.…
Updated stellar rates for the reaction 23Mg(p,gamma)24Al are calculated by using all available experimental information on 24Al excitation energies. Proton and gamma-ray partial widths for astrophysically important resonances are derived…
New stellar models with mass ranging between 4 and 8 Mo, Z=0 and Y=0.23 are presented. The models have been evolved from the pre Main Sequence up to the Asymptotic Giant Branch (AGB). At variance with previous claims, we find that these…
Nuclear reactions drive the stellar evolution and contribute to the stellar and galactic chemicals abundances. New determinations of the nuclear reaction rates for key fusion reactions of stellar evolution are now available, paving the way…
Among the uncertainties of stellar evolution theory, we investigate how the $^{12}$C($\alpha, \gamma$)$^{16}$O reaction rate affects the evolution of massive stars for the initial masses of $M ({\rm ZAMS})=$ 13 - 40 M$_\odot$ and the solar…
A new astrophysical reaction rate for $^{12}$C($\alpha,\gamma$)$^{16}$O has been evaluated on the basis of a global R-matrix fitting to the available experimental data. The reaction rates of $^{12}$C($\alpha,\gamma$)$^{16}$O for stellar…
We investigate the dependence of the carbon and oxygen production in stars on the 3-alpha rate by varying the energy of the 02+-state of 12C and determine the resulting yields for a selection of low-mass, intermediate-mass, and massive…
The method developed by Raffelt (1990a,b,c) to estimate a possible increase in the standard values of the helium-core mass at the tip of the red giant branch, $\Mc$, from properties of the color-magnitude diagrams of Galactic globular…
There is now strong evidence that some stars have been born with He mass fractions as high as $Y \approx 0.40$ (e.g., in $\omega$ Centauri). However, the advanced evolution, chemical yields, and final fates of He-rich stars are largely…