| Project/Area Number |
18540231
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NOMOTO Ken'ichi The University of Tokyo, Institute for the Physics and Mathematics of the Universe, Professor (90110676)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Tomoharu The University of Tokyo, Graduate School of Science, Assistant Professor (20280935)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,880,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥480,000)
Fiscal Year 2007: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | stellar evolution / stellar abundance / hypernova / nucleosynthesis / galactic chemical evolution / supernova / black hole / neutron star / 恒星の進化 / 大質量星 / 金属欠乏星 / 宇宙初代星 / 質量関数 / 宇宙化学進化 |
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| Research Abstract |
The first generation of stars, called Population III stars, in the Universe do not contain heavy elements. It is one of the main focus of current astronomy that how much are their typical masses, i.e., their mass function, because those masses determine whether the first stars are the source of cosmic re-ionization, and the origin of intermediate and super-massive black holes. In this study, we modeled the evolution and supernova explosions of the first stars, and tried to estimate their typical masses and explosion energies from the comparison between nucleosynthesis and the observed chemical abundances of extremely metal-poor (EMP) stars. We focus on the peculiar abundance pattern of EMP stars, which is very different from the solar abundance.
We have calculated the evolution of Population III (Pop III) stars that undergo mass accretion and increase their masses from 1 solar mass. The calculation has been conducted through the phase of gravitational collapse. Our findings are summarized as follows.
1) First we adopted the accretion rate as estimated from the 3 dimensional cosmological simulation of the first star formation. The mass of the Pop III.1 stars increase through 1000 solar mass, and intermediate mass black holes are formed. Such intermediate mass black holes can be the seeds of super-massive black holes, thus being very interesting objects.
2) Next we studied Pop III.2 stars whose mass accretion is stopped by the feedback effect of Pop III.1 stars. We found that those stars increase their masses through 50-100 solar mass. These stars undergo gravitational collapse and nucleosynthesis to produce the abundance pattern observed in EMP stars.
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