Search for Population III Stars and study on Stars in Down of the Universe

寻找第三族恒星并研究宇宙下方的恒星

• 批准号: 15204010
• 负责人: FUJIMOTO Masayuki
• 金额: $ 26.79万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15204010/
• 关键词: Stellar evolution; nucleosynthesis; spectroscopy; supernova explosion; star formation; early universe; first generation starts; extremely metal-poor star; 元素組成; 恒星分光; 恒星大気構造; 炭素星; 元素合成

This study started after the discovery a giant HE 0107-5240 with the iron abundance as small as 1/200,000 of the solar value and aimed at exploring the characteristics of surface abundances systematically and discussing the search for of the extremely metal-poor stars, formed during the formation of the Galaxy, and in particular, the population III stars that are the survivors of first generation stars made of matter completely devoid of metals. Through the 3 years research, we have made considerable progress in understanding the properties of these relics from the early Universe both theoretically and observationally from the viewpoints of their formation, evolution and nucleosynthesis and from the spectroscopic study.For the theoretical side, we find that in the extremely metal-poor stars, neutron capture reactions occur during the helium shell-flashes invoked by hydrogen mixing and yield not only the light elements from carbon, to sodium, magnesium, and aluminum but also, heavy s-pr … More ocess elements such as strontium as observed form extremely metal-poor stars.We also elucidate the peculiar aspects of their evolution and supernova nucleosynthesis of under the devoid of metals and demonstrate that supernova explosion can produce the yields of various ratio between carbon to iron including such a large ratio as observed if the effect of non-spherical-symmetry is taken into account. In addition it is shown that the enhancement of odd nuclei such as sodium and aluminum can be produced during the carbon-burning in extremely metal-poor massive stars. As for the star formation, we proposed a scenario to give birth to low-mass stars that can survive to date under with the effect of irradiation and supernova explosion of massive stars taken into account in the primordial clouds.For the observational research, we clarify the nature of extremely metal poor-stars as to the carbon-enrichment and also to the enhancement of neutron-capture elements on the basis of the spectroscopic data from Subaru HDS of the projects organized by participants of this research program. In particular, most remarkable is the discovery of sub-giant HE 1327-232 of the metal-poorest star known t data in collaboration with USA and German research teams. This is the second star below metallicity below 1/100,000 of solar value and along the theoretical development, may serve as a probe to stimulate future progress in the study of the early Universe. Less

本研究是在发现一颗铁丰度仅为太阳值1/200,000的巨型HE 0107-5240之后开始的，旨在系统地探讨其表面丰度特征，并讨论寻找银河系形成过程中形成的极度贫金属恒星，特别是由完全不含金属的物质构成的第一代恒星的幸存者，即第三族恒星。通过三年的研究，我们从理论和观测上，从它们的形成、演化、核合成以及光谱研究的角度，在理解这些早期宇宙遗迹的性质方面取得了相当大的进展。在理论方面，我们发现，在金属极度贫乏的恒星中，在氢混合引起的氦壳层闪光期间发生中子俘获反应，不仅产生来自中子的轻元素 碳、钠、镁和铝，还有重 s-pr ... 更多的 s-pr 等元素，如观测到的锶，形成了极其贫金属的恒星。我们还阐明了它们在缺乏金属的情况下演化和超新星核合成的特殊方面，并证明超新星爆炸可以产生碳与铁之间各种比例的产量，包括观察到的如此大的比例，如果效果 考虑了非球对称性。此外，研究表明，在金属极度贫乏的大质量恒星的碳燃烧过程中，可以产生诸如钠和铝之类的奇数核的增强。在恒星形成方面，我们提出了一种设想，即考虑到原始云中大质量恒星的辐照和超新星爆炸的影响，诞生出能够存活至今的低质量恒星。在观测研究方面，我们根据Subaru HDS的光谱数据，阐明了极端金属贫恒星的碳富集和中子俘获元素增强的性质。 该研究计划的参与者组织的项目。其中最引人注目的是与美国和德国研究团队合作发现的已知金属最贫恒星的亚巨星HE 1327-232。这是第二颗金属丰度低于太阳值 1/100,000 的恒星，随着理论的发展，可能会作为一个探针，刺激早期宇宙研究的未来进展。较少的

项目成果

Subaru Spectroscopy of the Interacting Type Ia Supernova SN 2002ic: Evidence of a Hydrogen-rich, Asymmetric Circumstellar Medium

• DOI: 10.1086/420698
• 发表时间: 2003-11
• 期刊: The Astrophysical Journal Letters
• 作者: J. Deng;K. Kawabata;Y. Ohyama;Ken'ichi Nomoto;P. Mazzali;P. Mazzali;Lifan Wang;David J. Jeffery;M. Iye;H. Tomita;Y. Yoshii

Dynamical response to supernova-induced gas removal in two-component spherical galaxies

双组分球形星系中超新星引起的气体去除的动力学响应

• 发表时间: 2003
• 期刊: Monthly Notice of the Royal Astronomical Society 340
• 作者: Hasegawa;A.;J.Nakajima;N.Umino;S.Miura;Masahiro Nagashima
• 通讯作者: Masahiro Nagashima

Mass Function of Low-Mass Dark Halos

低质量暗晕的质量函数

• 发表时间: 2004
• 期刊: Astrophysical Journal 605
• 作者: Yahagi;Hideki
• 通讯作者: Hideki

Low-Mass Star Formation, Triggered by Supernova in Primordial Clouds

由原始云中的超新星引发的低质量恒星形成

• 发表时间: 2005
• 期刊: Astrophysical Journal 622
• 作者: Machida;Masahiro
• 通讯作者: Masahiro

Precursors and Main Bursts of Gamma-Ray Bursts in a Hypernova Scenario

超新星场景中伽马射线暴的前体和主要爆发

• 发表时间: 2005
• 期刊: ApJ 633
• 作者: Umeda;H.;Tominaga;N.;Maeda;K.;Nomoto;K.
• 通讯作者: K.