The p-process in exploding rotating massive stars

Abstract

The p-process nucleosynthesis can explain proton-rich isotopes that are heavier than iron, which are observed in the Solar System, but discrepancies still persist and important questions concerning the astrophysical site(s) of the p-process remain unanswered. We investigate how the p-process operates in exploding rotating massive stars that have experienced an enhanced s-process nucleosynthesis during their life through rotational mixing. We computed 25 $M_{\odot }$ stellar models at a metallicity of $Z=10^{-3}$ with different initial rotation velocities and rates for the uncertain ${}^{17}$O($\alpha$,$\gamma$)${}^{21}$Ne reaction. The nucleosynthesis calculation, followed with a network of 737 isotopes, was coupled to stellar evolution, and the p-process nucleosynthesis was calculated in post-processing during both the final evolutionary stages and spherical explosions of various energies. In our models, the p-nuclides are mainly synthesized during the explosion, but not much during the ultimate hydrostatic burning stages. The p-process yields mostly depend on the initial number of trans-iron seeds, which in turn depend on the initial rotation. We found that the impact of rotation on the p-process is comparable to the impact of rotation on the s-process. From no to fast rotation, the s-process yields of nuclides with mass number $A<140$ increase by $3-4$ dex, and so do the p-process yields. Fast rotation with a lower ${}^{17}$O($\alpha ,\gamma$) rate significantly produces s- and p-nuclides with $A\ge 140$. Our results suggest that the contribution of core-collapse supernovae from massive stars to the solar (and Galactic) p-nuclei has been underestimated in the past, and more specifically, that the contribution from massive stars with sub-solar metallicities may even dominate. A more detailed study including stellar models with a wide range of masses and metallicities remains to be performed.

12 pages, 13 figures, 2 tables, accepted for publication in A&A

References in corpus (17)

• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers
• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production
• The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars
• The Explosion of Helium Stars Evolved With Mass Loss
• s-Process Nucleosynthesis in Advanced Burning Phases of Massive Stars
• Databases and tools for nuclear astrophysics applications BRUSsels Nuclear LIBrary (BRUSLIB), Nuclear Astrophysics Compilation of REactions II (NACRE II) and Nuclear NETwork GENerator (NETGEN)
• The Connection between Gamma-Ray Bursts and Extremely Metal-Poor Stars: Black Hole-forming Supernovae with Relativistic Jets
• Aspherical Properties of Hydrodynamics and Nucleosynthesis in Jet-induced Supernovae
• Testing the role of SNe Ia for Galactic chemical evolution of p-nuclei with 2D models and with s-process seeds at different metallicities
• Measurement of the reaction O-17(α,n)Ne-20 and its impact on the s process in massive stars
• First direct measurement of resonance strengths in 17O(α, γ)21Ne
• Pre-supernova mixing in CEMP-no source stars
• A strong neutron burst in jet-like supernovae of spinstars
• A direct measurement of the 17O(a,g)21Ne reaction in inverse kinematics and its impact on heavy element production