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Description
A huge number of neutrinos radiated at supernova explosions is considered to have an important role for production of some rare isotopes (ν-process). Although some measurements such as astronomical observation of 19F in metal poor stars and the existence of a short-lived radioisotope of 92Nb at the solar system formation in primitive meteorites are candidates for the ν-process, there is no clear evidence that the ν-process actually occurred in the universe. Our previous prediction has demonstrated that the correlation between the isotopic ratios at least in two different elements can constrain the astrophysical conditions where presolar grains were produced [1]. Here we present the result that a detailed core-collapse a supernova (CCSN) nucleosynthesis calculation including the ν-process reproduce the correlation between enhancement of 138La/139La and 50Ti/48Ti observed in calcium-aluminum-rich inclusions (CAIs) in primitive meteorites, which are the oldest solids in our solar system. In our calculation, 138La is predominantly produced from 138Ba by the charged current reactions with electron neutrinos, and 50Ti is produced by successive neutron capture reactions on Ti isotopes.
This result is consistent with the recent result that the isotopic abundance anomalies of Ti isotopes observed in CAIs can be only explained by the slow neutron capture reactions (s-process) in C-shell burning in massive star before the SN explosion [2]. The present result shows that the La-Ti correlation observed in the CAIs is the evidence that the ν-process in CCSNe occur in the universe, and that its product contributed to the early solar materials. This gives a hint to the long-standing problem whether the collapse of the proto-solar nebula was triggered by the shock by a nearby SN. We present the detailed nucleosynthesis calculation with key neutrino-nucleus reactions and the role of the s-process in C-shell burning. We also explain the model of the mixing of the SN ejecta to the proto-solar nebula.
[1] X. Yao, et al. ApJ, 980, 247 (2025).
[2] T. Iizuka, et al. ApJL, 979, L29 (2025).
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