2004 Fiscal Year Final Research Report Summary
Study on a formation and chemical evolution of the Galaxy based on spectroscopic observations of metal-poor stars
| Project/Area Number |
13640246
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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 | Tokai University |
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Principal Investigator |
HIDAI Masahide Tokai University, Liberal Arts Education Center, Professor, 総合教育センター, 教授 (90173179)
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| Project Period (FY) |
2001 – 2004
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| Keywords | metal-poor stars / spectroscopy / The Galaxy / chemical composition / nucleosynthesis / chemical evolution / Population III |
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| Research Abstract |
1. Our spectroscopic studies of alpha- elements, O, Si, S, and Ca, in metal-poor stars were carried out to investigate their behaviors against metalicity [Fe/H]. As for O, the abundance derived from the triplet lines was found to show a flat trend. The behaviors of Si and Ca show a correlated trend and were found to be classified into three groups based on dynamical properties. As for S, our result of an increasing trend with decreasing [Fe/H] in a paper of 2002 was first derived from a large sample, and inspired other groups as well as us to make further studies of S behavior. Our result obtained in a paper of 2005 confirmed that S shows a flat trend in -4 <[Fe/H]<-1, which may be explained by chemical evolution models based on standard supernovae nucleosynthesis.
2. Other light elements of Li, Na, and K were also studied and found to provide the new results being different from the previous ones.
3. The behavior of Zinc in very metal-poor stars was found to show an increasing trend below [Fe/H]<-3, which gives an important constraints to supernova models.
4. The behaviors of r-process elements were found to show a large star-to-star scatter and to be explained by r-process nucleosynthesis. However, an unknown process was needed for an explanation of behaviors of Sr and Ba.
5. The most iron-deficient star was discovered. The star may be a population III, or even if not, it gives strong constraints to a nature of the first generation stars in the beginning of the Galaxy.
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Research Products
(29 results)
