We demonstrate that rapid expansion of the shocked surface layers of an O-Ne-Mg core following its collapse can result in r-process nucleosynthesis. As the supernova shock accelerates through these layers, it makes them expand so rapidly that free nucleons remain in disequilibrium with alpha-particles throughout most of the expansion. This allows heavy r-process isotopes up to the actinides to form in spite of the very low initial neutron excess of the matter. We estimate that yields of heavy r-process nuclei from this site may be sufficient to explain the Galactic inventory of these isotopes. The material in the shocked hydrogen envelope of such stars is both heated to temperatures of greater than 10 9 K by the supernova shock and subject to an intense flux of neutrinos. Very high neutron number densities greater than 1020 cm -3 can be obtained. With the large proton and neutron number densities and the high temperatures in the shocked hydrogen envelope near the base, heavy nuclei with mass number up to 200 can be produced from an initial mixture of H and He only. This implies a possible novel mode of heavy element nucleosynthesis.
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机译：我们证明O-Ne-Mg核震荡后其表层的迅速膨胀会导致r-过程核合成。随着超新星震动在这些层中的加速，它使它们迅速膨胀，以至于在整个膨胀过程中，自由核子均与α粒子保持不平衡。尽管该物质的初始中子过量非常低，但仍允许形成高达r系元素的重r过程同位素。我们估计，从该位点产生的重r过程核的产量可能足以解释这些同位素的银河库存。此类恒星的受激氢包膜中的物质都被超新星激波加热到高于10 9 K的温度，并受到强烈的中微子通量。可以获得大于1020 cm -3的非常高的中子数密度。由于质子和中子数密度大，并且在靠近基座的受激氢包膜中存在高温，仅由H和He的初始混合物就可以产生质量数高达200的重核。这暗示了重元素核合成的可能新模式。
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