The first billion years of the Universe: approach from the elemental abundance of metal-poor stars

2014 Fiscal Year Final Research Report

• Project/Area Number: 25800115
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy
• Research Institution: The University of Tokyo (2014); National Astronomical Observatory of Japan (2013)
• Principal Investigator: KOMIYA Yutaka 東京大学, 理学(系)研究科(研究院), 研究員 (10455777)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 金属欠乏星 / 初代星 / 元素合成 / ｒ過程 / Hyper metal-poor star

Outline of Final Research Achievements

Metal (elements heavier than lithium) were not synthesized in the Big Bang nucleosynthesis but formed in the stellar interior or at supernova explosion. Metal-poor stars are relics from the early Universe. We model the enrichment history of heavy elements in the early Universe considering hierarchical galaxy formation.
We investigate the enrichment history of r-process elements. The r-process is a process to synthesize elements heavier than iron-group. It is known that the r-process element abundances of metal-poor stars show large scatter. We successfully reproduce the observed distribution of r-process element abundances by considering the hierarchical galaxy formation process.
We also show that hyper metal-poor stars, which are the most iron-deficient stars ever identified, were formed without metal. The surface pollution by accretion of interstellar medium can account for the surface metal abundance of hyper metal-poor stars.

Free Research Field

天文学