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The first metal enrichment in the universe was made by supernova (SN) explosions of population (Pop) III stars. The trace remains in abundance patterns of extremely metal-poor (EMP) stars. We investigate the properties of nucleosynthesis in Pop III SNe by means of comparing their yields with the abundance patterns of the EMP stars. We focus on (1) jet-induced SNe with various energy deposition rates [$dot{E}_{rm dep}=(0.3-1500)times10^{51}{rm ergs s^{-1}}$], and (2) SNe of stars with various main-sequence masses ($M_{rm ms}=13-50M_odot$) and explosion energies [$E=(1-40)times10^{51}$ergs]. The varieties of Pop III SNe can explain varieties of the EMP stars: (1) higher [C/Fe] for lower [Fe/H] and (2) trends of abundance ratios [X/Fe] against [Fe/H].
We perform calculations of dark photon production and decay in the early universe for ranges of dark photon masses and vacuum coupling with standard model photons. Simultaneously and self-consistently with dark photon production and decay, our calcul
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Recent observations of r-process-enriched metal-poor star abundances reveal a non-uniform abundance pattern for elements $Zleq47$. Based on non-correlation trends between elemental abundances as a function of Eu-richness in a large sample of metal-po
We present preliminary results of stellar structure and nucleosynthesis calculations for some early stars. The study (still in progress) seeks to explore the expected chemical signatures of second generation low- and intermediate-mass stars that may
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