Nucleosynthesis in 2D core-collapse supernovae of 11.2 and 17.0 M⊙ progenitors: Implications for Mo and Ru production (original) (raw)
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Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016), 2017
We perform detailed nucleosynthesis calculations for two long-term, 2D simulations of core-collapse supernovae. We find that elements are produced up to Ru (Z = 44) and observe abundance patterns that are characteristic of a νp-process. One important characteristic of the long-term simulation is that there is still accretion of matter onto the proto-neutron star and unbinding of matter in some other regions at the time when the simulations stop (around 7s). Dividing the tracer particles into different bins according to their peak temperatures enables us to study and compare the nuclear compositions of these bins for the different simulations.
Proceedings of 11th Symposium on Nuclei in the Cosmos — PoS(NIC XI)
We have performed a large-scale nucleosynthesis parameter study within the high-entropy-wind (HEW) scenario of core-collapse supernovae with the primary aim to obtain indications for the production conditions of the classical 'p-only' isotopes of the light trans-Fe elements in the Solar System (SS). We find that in moderately neutron-rich winds, sizeable abundances of p-, sand r-process nuclei between 64 Zn and 104 Ru are co-produced. Taking the peculiar compositions of the 7 stable Mo isotopes in (i) the SS and (ii) in specific presolar SiC X-grains as particularly challenging examples, our results show that the HEW ejecta can reproduce both, (i) the SS-ratio of 92 Mo/ 94 Mo with isotopic yields per SN event in the 10 −8 M ⊙ range, and (ii) the puzzling grain data of the Argonne / Chicago group. These results are in principal agreement with earlier studies, and may provide further means to revise the abundance estimates in the historical "lightp", "weak-s" and "weak-r" process regions.
Nucleosynthesis in Massive Stars with Improved Nuclear and Stellar Physics
The Astrophysical Journal, 2002
We present the first calculations to follow the evolution of all stable nuclei and their radioactive progenitors in stellar models computed from the onset of central hydrogen burning through explosion as Type II supernovae. Calculations are performed for Pop I stars of 15, 19, 20, 21, and 25 M ⊙ using the most recently available experimental and theoretical nuclear data, revised opacity tables, neutrino losses, and weak interaction rates, and taking into account mass loss due to stellar winds. A novel "adaptive" reaction network is employed with a variable number of nuclei (adjusted each time step) ranging from ∼ 700 on the main sequence to 2200 during the explosion. The network includes, at any given time, all relevant isotopes from hydrogen through polonium (Z = 84). Even the limited grid of stellar masses studied suggests that overall good agreement can be achieved with the solar abundances of nuclei between 16 O and 90 Zr. Interesting discrepancies are seen in the 20 M ⊙ model and, so far, only in that model, that are a consequence of the merging of the oxygen, neon, and carbon shells about a day prior to core collapse. We find that, in some stars, most of the "p-process" nuclei can be produced in the convective oxygen burning shell moments prior to collapse; in others, they are made only in the explosion. Serious deficiencies still exist in all cases for the p-process isotopes of Ru and Mo.
R-Process Nucleosynthesis in Supernovae
A lmost all of the hydrogen and helium in the cosmos, along with some of the lithium, was created in the first three minutes after the Big Bang. Two more light elements, beryllium and boron, are synthesized in interstellar space by collisions between cosmic rays and gas nuclei. All of the other elements in nature are formed by nuclear reactions inside stars.
Nuclear Processes in Stellar Explosions
Fission and Properties of Neutron-Rich Nuclei, 2008
We know two kind of stellar explosion events; shock induced explosions of core collapsing massive stars known as type 11 supemovae, and accretion induced thermonuclear explosions such as type Ia supernovae, X-ray bursts, and novae in accreting binary systems. The type I1 supernova shock front causes rapid increase of density and temperature conditions in the stellar material initiating fast neutron or gamma induced nucleosynthesis processes such as the r-process and the p-process which contribute to the heavy element abundance distribution in our universe. Thermonuclear stellar explosions on the other hand are driven by nuclear ignition of dense stellar material at highly electron degenerate conditions. The ignition conditions are defined by the reaction rates of heavy ion fusion processes of stellar core material for type Ia supernovae, or by rapid nuclear fusion processes such as the hot CNO cycles or the rp-process in the stellar atmosphere of freshly accreted matter. This paper will provide a summary of the nucleosynthesis signatures of the rapid nucleosynthesis processes in stellar explosions and will highlight their impact on the associated energy release and the production of heavy elements as observed in our galaxy.
The γ-process nucleosynthesis in core-collapse super-novae
EPJ Web of Conferences
Neutron-capture processes made most of the abundances of heavy elements in the Solar System, however they cannot produce a number of rare proton-rich stable isotopes (p–nuclei) lying on the left side of the valley of stability. The γ–process, i.e., a chain of photodisintegrations starting on heavy nuclei, is recognized and generally accepted as a feasible process for the synthesis of p–nuclei in core collapse supernovae (CCSNe). However this scenario still leaves some puzzling discrepancies between theory and observations. We aim to explore in more detail the γ–process production from massive stars, using different sets of CCSNe models and the latest nuclear reaction rates. Here we show our preliminary analysis, by identifying the γ–process sites and focusing on progenitors of CCSNe that experience a C–O shell merger just before the collapse of the Fe core.
The influence of the explosion Mechanism on the Fe-group ejecta of core collapse supernovae
Proceedings of the International Astronomical Union, 2005
Core collapse supernovae are responsible for at least half of the galactic inventory of Fe-group elements and probably for most of the Fe-group abundances seen in metal poor stars. Recent simulations show the emergence of a proton-rich (Y e > 0.5) region in the innermost ejected mass zones due to the neutrino interaction with matter. We explore the nucleosynthesis implications of these findings that result in enhanced abundances of 45 Sc, 49 Ti, and 64 Zn, which is consistent with chemical evolution studies and observations of low metallicity stars.
Nucleosynthesis in Massive Stars-Including All Stable Isotopes
2000
We present the first calculations to follow the evolution of all stable isotopes (and their abundant radioactive progenitors) in a finely zoned stellar model computed from the onset of central hydrogen burning through explosion as a Type II supernova. The calculations were performed for a 15 M ⊙ Pop I star using the most recently available set of experimental and theoretical nuclear data, revised opacity tables, and taking into account mass loss due to stellar winds. We find the approximately solar production of proton-rich isotopes above a mass number of A = 120 due to the γ-process. We also find a weak s-process, which along with the γ-process and explosive helium and carbon burning, produces nearly solar abundances of almost all nuclei from A = 60 to 85. A few modifications of the abundances of heavy nuclei above mass 90 by the s-process are also noted and discussed. New weak rates lead to significant alteration of the properties of the presupernova core.