Related papers: $^{14}$N(p,$\gamma)^{15}$O $S$ factor and the puzz…
We explore approximations to the effective $S$ factor for the $^7Be(p,\gamma)^8B$ reaction using different approximation for the integral over the Gamov peak. In the temperature range of interest for solar neutrino production, $S_{eff}(E)$…
The $^{12}\text{C}(\alpha,\gamma){}^{16}\text{O}$ reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced $\alpha$…
We discuss what appears the last hope for an astrophysical solution to the solar neutrino problem: a correlated variation of the astrophysical factors for the helium burning cross sections ($S_{33}$ and $S_{34}$) and either $S_{17}$ or the…
Standard solar models (SSM) are facing nowadays a new puzzle: the solar composition problem. New determinations of solar metal abundances lead SSM calculations to conflict with helioseismological measurements, showing discrepancies that…
14N(p,gamma)15O is one of the key reactions of nuclear astrophysics playing a role in various stellar processes and influencing energy generation of stars, stellar evolution and nucleosynthesis. For a reliable reaction rate calculation the…
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…
The abundances of the isotopes of the elements C, N and O are mainly affected by the cold CNO cycles in non-explosive stellar situations, or by the hot CNO chains that can develop in certain explosive sites, like classical novae. Helium…
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…
The fractionation of nitrogen (N) in star-forming regions is a poorly understood process. To put more stringent observational constraints on the N-fractionation, we have observed with the IRAM-30m telescope a large sample of 66 cores in…
The breakout reaction $^{15}$O($\alpha,\gamma$)$^{19}$Ne, which regulates the flow between the hot CNO cycle and the rp-process, is critical for the explanation of the burst amplitude and periodicity of X-ray bursters. We report on the…
High energy solar neutrinos can come from the hep reaction ^3He(p,\nue^+)^4He with a large end point energy of 18.8 MeV. Understanding the hep reaction may be important for interpreting solar neutrino spectra. We calculate the contribution…
The proton radiative capture $^{12,13}$C$(p,{\gamma})$ reactions at astrophysical energies, key processes in the CNO cycle, are revisited in the potential model with the proton-nucleus potential for both the scattering and bound states…
The ground-state Gamow-Teller transition in the decay of 14O is strongly hindered and the electron spectrum deviates markedly from the allowed shape. A reanalysis of the only available data on this spectrum changes the branching ratio…
The $^{22}$Ne($p,\gamma$)$^{23}$Na reaction, part of the neon-sodium cycle of hydrogen burning, may explain the observed anticorrelation between sodium and oxygen abundances in globular cluster stars. Its rate is controlled by a number of…
LUNA, Laboratory for Underground Nuclear Astrophysics at Gran Sasso, is measuring fusion cross sections down to the energy of the nucleosynthesis inside stars. Outstanding results obtained up to now are the cross-section measurements within…
Neutron-capture reactions on $^{18}$F in the helium-burning shell play an important role in the production of $^{15}$N during core-collapse supernovae. The competition between the $^{18}$F($n,p/\alpha$)$^{18}$O/$^{15}$N reactions controls…
The astrophysical $S$-factor for the reaction $^7$Be(p,$\gamma$)$^8$B up to an energy of 2~MeV (c.m.) and the capture cross section of $^7$Li(n,$\gamma$)$^8$Li up to 1~MeV (c.m.) are calculated using the Direct Capture model (DC). Both…
The Super-Kamiokande best global fit, which includes data from SNO, Gallium and Chlorine experiments, results in a hep neutrino contribution to the signals that, even after oscillation, is greater than the SSM prediction. The solar hep…
The ratio of metal abundance to hydrogen abundance of the solar photosphere, $(Z/X)_{s}$, has been revised several times. Standard solar models, based on these revised solar abundances, are in disagreement with seismically inferred results.…
The possibility of description of the experimental data for the astrophysical S-factor of the radiative proton capture on 15N at the energies from 50 to 1500 keV was considered in the framework of the modified potential cluster model with…