Nuclei in the Cosmos (NIC XVII)

Session

The s-process

18 Sept 2023, 09:15

211. Questions in Experimental Nuclear Astrophysics

Prof. Michael WIESCHER (University of Notre Dame)

18/09/2023, 09:15

The s-process

Invited

Nuclear Astrophysics is low energy reaction physics – with stable and radioactive nuclei. The goal of the field is to understand critical reaction cross sections at stellar energies which are typically not directly accessible by experiment. The reaction rates therefore depend on reliable extrapolation of the reaction rates towards the stellar energy regime. A number of near threshold effects...

13. New constraints on the $^{13}$C$(\alpha,n)^{16}$O reaction

Richard DEBOER (University of Notre Dame)

18/09/2023, 09:45

The s-process

Oral

Neutron production for the slow neutron capture process ($s$-process) is dominated by $(\alpha,n)$ reactions on light nuclei during stellar helium burning. Chief amount these is the $^{13}$C$(\alpha,n)^{16}$O reaction, whose low energy cross section is enhanced by the presence of broad resonances and subthreshold states. Experimental measurements have been reported recently at both the LUNA...

46. New determination of $^{17}$O+$\alpha$ reaction rates and impact on the s-process in metal-poor rotating massive stars

Faïrouz HAMMACHE (IJCLab-Orsay)

18/09/2023, 10:00

The s-process

Oral

The efficiency of the weak s-process in low metallicity rotating massive stars depends strongly on the ratio of the reaction rates of the two competing $^{17}$O($\alpha$,n)$^{20}$Ne and $^{17}$O($\alpha$,$\gamma$)$^{21}$Ne reactions, which impacts the poisoning effect of $^{16}$O that consumes the neutrons released by the $^{22}$Ne($\alpha$,n)$^{25}$Mg reaction [1] .
However, the reaction...

95. The s-process in AGB stars

Amanda KARAKAS (Monash University)

18/09/2023, 10:45

Underground nuclear astrophysics

Invited

About half of the solar abundance of elements heavier than iron are made by the slow neutron capture process (s-process) occurring in low and intermediate-mass asymptotic giant branch (AGB) stars. Elements are mixed from the core to the surface and then expelled into the interstellar medium through strong stellar winds. In comparison to the rapid neutron capture process, modelling the...

20. The s process - nuclear physics aspects

Rene REIFARTH (Goethe University Frankfurt (DE))

18/09/2023, 11:15

The s-process

Invited

About half of the elements heavier than iron are produced in rather quite stellar environments during long exposures of seed material with neutrons. The interplay between neutron captures and beta-decays enables the production of all elements between iron and bismuth. This process is called slow neutron capture process, or s process.

Radioactive isotopes on the s-process path can act as...

100. New s-process yields and surface abundances from asymptotic giant branch models

Balázs SZÁNYI (Konkoly Observatory, CSFK; University of Szeged)

18/09/2023, 11:45

The s-process

Oral

Theoretical stellar nucleosynthesis calculations allow direct comparison between predicted stellar abundances and observations, as well as interpretation of the isotope composition of meteoritic components. Our computational method for calculating predictions for stellar abundances from AGB stars involves two steps: first, the evolution of the stellar structure is calculated by the Stromlo...