2003 Fiscal Year Final Research Report Summary
Nucleosynthesis in Population III Stars and Chemical Abundances of Extremely Metal-Poor Stars
| Project/Area Number |
14540223
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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, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (90110676)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Tomoharu The University of Tokyo, Graduate School of Science, Research Associtate, 大学院・理学系研究科, 助手 (20280935)
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| Project Period (FY) |
2002 – 2003
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| Keywords | stellar evolution / stellar population / stellar abundance / supernova / hypernova / nucleosynthesis / iron / galactic chemical evolution |
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| Research Abstract |
The first generation of stars, called Population III stars, in the Universe do not contain heavy elements. In this study, we tried to investigate their nature from the comparison between nucleosynthesis and the chemical abundances of extremely metal-poor (EMP) stars. We focus on the peculiar abundance pattern of EMP stars. For example, (Mn, Cr)/Fe decrease while (Zn, Co)/Fe increase toward smaller metallicity. Such an abundance pattern may stem from nucleosynthesis in Pop III stars.
In the first year of this study, we calculated the evolution and explosions of Pop III stars for a wide range of stellar masses and explosion energies and found interesting features of their nucleosynthesis In the second year, we extended our study to the aspherical explosion models. Our findings are summarized as follows:
1)We found that nucleosynthesis in Hypernova explosions can explain the above abundance patterns of EMP stars.
2)Pair instability supernovae in 130-300 M_【of sun】 stars cannot explain the abundances of EMP stars.
3)Among the EMP stars, many C and N-rich stars with quite large rations of (C, N)/Fe have been discovered. we showed that such large rations can be explained with the black-hole-forming supernovae.
4)Variations among the C-rich EMP stars can be explained with the mixing and the fallback mechanism.
5)This implies many black-holes were formed from the first generation supernovae.
6)Bipolar explosions induce naturally the mixing-fallback like events.
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[Publications] Kinugasa, K., Kawakita, H., Ayani, K., Kawabata, T., Yamaoka, H., Deng, J., Mazzali, P.A., Maeda, K., Nomoto, K.: "Early-Phase Spectra of Hypernova SN 2002ap"ApJ. 577. L97-L101 (2002)
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[Publications] Kawabata, K.S, Jeffery, D.J.Iye, M., Ohyama, Y., Kosugi, G., Kashikawa, N., Ebizuka, N., Sasaki, T., Sekiguchi, K., Nomoto, K., azzali, P.A., Eeng, j.,, k.: "Spectropolarimetry of SN 2002ap: A High Velocity Asymmetric Explosion"ApJ. 580. L39-L42 (2002)
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[Publications] Gerardy, C.L., Fesen, R.A., Nomoto, K., Maeda, K., Hoeflich, P., Wheeler, J.C.: "Carbon Monoxide in the Type Ic Supernova 2000ew"PASJ. 54. 905-910 (2002)
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[Publications] Mazzali, P.A., Deng, J., Tomonaga, N., Maeda, K., Nomoto, K., Matheson, T., Kawabata, K.S., Staned, K.Z., Garnavich, P.M.: "The Type Ic Hypernova SN 2003dh/GRB 030329"Astrophys.J.. 599. L95-L98 (2003)
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