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Context.Theγprocess in core-collapse supernovae (CCSNe) can produce a number of neutron-deficient stable isotopes heavier than iron (pnuclei). However, current model predictions do not fully reproduce solar abundances, especially for92, 94Mo and96, 98Ru. Aims.We investigate the impact of different explosion energies and parametrizations on the nucleosynthesis ofpnuclei, by studying stellar models with different initial masses and different CCSN explosions. Methods.We compared thep-nucleus yields obtained using a semi-analytical method to simulate the supernova to those obtained using hydrodynamic models. We explored the effect of varying the explosion parameters on thep-nucleus production in two sets of CCSN models with initial masses of 15, 20, and 25M⊙at solar metallicity. We calculated a new set of 24 CCSN models (eight for each stellar progenitor mass) and compared our results with another recently published set of 80 CCSN models that includes a wide range of explosion parameters: explosion energy or initial shock velocity, energy injection time, and mass location of the injection. Results.We find that the totalp-nucleus yields are only marginally affected by the CCSN explosion prescriptions if theγ-process production is already efficient in the stellar progenitors due to a C−O shell merger. In most CCSN explosions from progenitors without a C−O shell merger, theγ-process yields increase with the explosion energy by up to an order of magnitude, depending on the progenitor structure and the CCSN prescriptions. The general trend of thep-nucleus production with the explosion energy is more complicated if we look at the production of singlepnuclei. The lightp-nuclei tend to be the most enhanced with increasing explosion energy. In particular, for the CCSN models where theα-rich freeze-out component is ejected, the yields of the lightestpnuclei (including92, 94Mo and96Ru) increase by up to three orders of magnitude. Conclusions.We provide the first extensive study using different sets of massive stars of the impact of varying CCSN explosion prescriptions on the production ofpnuclei. Unlike previous expectations and recent results in the literature, we find that the average production ofpnuclei tends to increase with the explosion energy. We also confirm that the pre-explosion production ofpnuclei in C−O shell mergers is a robust result, independent of the subsequent explosive nucleosynthesis. More generally, a realistic range of variations in the evolution of stellar progenitors and in the CCSN explosions might boost the CCSN contribution to the galactic chemical evolution ofpnuclei.
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This content will become publicly available on August 22, 2026
Production of Radioactive 22 Na in Core-collapse Supernovae: The Ne-E(L) Component in Presolar Grains and Its Possible Consequences on Supernova Observations
Abstract Presolar graphite grains carry the isotopic signatures of their parent stars. A significant fraction of presolar graphites show isotopic abundance anomalies relative to solar for elements such as O, Si, Mg, and Ca, which are compatible with nucleosynthesis in core-collapse supernovae (CCSNe). Therefore, they must have condensed from CCSN ejecta before the formation of the Sun. Their most puzzling abundance signature is the22Ne-enriched component Ne-E(L), interpreted as the effect of the radioactive decay of22Na (T1/2= 2.6 yr). Previous works have shown that if H is ingested into the He shell and not fully destroyed before the explosion, the CCSN shock in the He-shell material produces large amounts of22Na. Here we focus on such CCSN models, showing a radioactive26Al production compatible with grain measurements, and analyze the conditions of22Na nucleosynthesis. In these models,22Na is mostly made in the He shell, with a total ejected mass varying between 2.6 × 10−3M⊙and 1.9 × 10−6M⊙. We show that such22Na may already impact the CCSN light curve 500 days after the explosion, and at later stages it can be the main source powering the CCSN light curve for up to a few years before44Ti decay becomes dominant. Based on the CCSN yields above, the 1274.53 keVγ-ray flux due to22Na decay could be observable for years after the first CCSN light is detected, depending on the distance. This makes CCSNe possible sites to detect a22Naγ-ray signature consistently with the Ne-E(L) component found in presolar graphites. Finally, we discuss the potential contribution from22Na decay to the Galactic positron annihilation rate.
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- Award ID(s):
- 1927130
- PAR ID:
- 10649180
- Publisher / Repository:
- IOP
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 990
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 19
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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