2000 Fiscal Year Final Research Report Summary
R-process Elements in the First Generation Stars and High-redshift Objects and the Galactic-and Cosmic-Age Problem.
| Project/Area Number |
10640236
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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 | National Astronomical Observatory |
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Principal Investigator |
KAJINO Toshitaka National Astronomical Observatory Divisin of Theoretical Astrophysics Associate Professor, 理論天文学研究系, 助教授 (20169444)
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| Co-Investigator(Kenkyū-buntansha) |
CHIBA Masashi National Astronomical Observatory Division of Astrometry and Celestial Mechanics Associate professor, 位置天文・天体力学研究系, 助教授 (50217246)
YOSHII Yuzuru University of Tokyo Institute of Astronomy, Professor, 天文教育研究センター, 教授 (00158388)
NOMOTO Kenichi University of Tokyo School of Science, Professor, 大学院・理学系研究科, 教授 (90110676)
TOKI Hiroshi Osaka University, Research Center for Nuclear Physics, Professor, 核物理研究センター, 教授 (70163962)
SADAKANE Kozo Osaka Kyoiku University, Faculty of Education, Professor, 教育学部, 教授 (20110794)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Nucleo-cosmochronology / Supernova Explosion / Neutrino / Neutron Star / R-process |
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| Research Abstract |
Observational study of the r-process elements was one of the utlimate purposes in this project, and it has just started in the year 2000 with the construction of SUBARU TELESCOPE which is equipped with High-Dispersion-Spectrograph (HDS) at the top of Mt.Kea. We have already carried out several test observations of SUBARU-HDS, which proves to work very well as we designed. Using this spectrograph, several metal-deficient halo stars have already been observed in order to detect metal absorption lines from Th232 (half life 14.1 Gy), U238 (4.5 Gy), Re187 (43.5 Gy), and many others. Data analysis is now underway. Theoretical studies of the r-process nucleosynthesis in supernova explosions also have been carried out to reach deep understanding of the nucleosynthesis mechanism. Actinoids are ideal heavy radioactive nuclei whose half life is of order of cosmic age. In this project, it was theoretically clarified that most heavy r-process elements, including some amounts of actinoids, are produced in explosive nucleosynthesis associated with Type II SN explosions. Dependence of the calculated yields of these elements on the physical conditions of stellar environments were studied in detail : It was clarified the relation between r-process abundance yields and physical parameters such as neutrino flux from the center of proto-neutron star, mass and radius of the neutron star, entropy and dynamic time scale which are closely related to the neutrino heating proceses in the neutrino-
driven winds.
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