Enrichment history of r-process elements in the Galactic halo and dwarf galaxies

2013 Fiscal Year Final Research Report

• Project/Area Number: 21540244
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Astronomy
• Research Institution: International Christian University
• Principal Investigator: ISHIMARU Yuri 国際基督教大学, 教養学部, 准教授 (90397068)
• Project Period (FY): 2009-04-01 – 2014-03-31
• Keywords: 理論天体物理学 / 銀河系 / 化学進化 / 金属欠乏星 / 矮小銀河 / ｒプロセス / 超新星爆発 / 中性子星

Research Abstract

Rapid neutron-capture process (r-process) produces most elements heavier than iron. Recent nucleosynthesis studies have pointed out serious difficulties for supernovae as a candidate of the r-process site. The other strong candidate is a neutron star merger. However, it has been suggested that neutron star mergers could not explain observed enhancement of r-process elements in metal-poor stars because the timescale of merger is regarded to be too long as 100 Myrs. In this study, using a new chemical evolution model, we have shown that neutron star mergers could reproduce observational abundances of metal-poor stars if the Galactic halo were formed from clusterings of sub-halos with various star formation histories. This result strongly supports neutron star mergers as the r-process site.

Research Products

• [Journal Article] 銀河の化学進化が物語るrプロセス元素の起源 (2014)
  • Author(s): 石丸友里
  • Journal Title: 天文月報(日本天文学会) Volume: 第107巻第2号 Pages: 96-106
• [Journal Article] Compact binary mergers as the origin of r-process elements in the Galactic halo (2014)
  • Author(s): Ishimaru, Y., Wanajo, S., & Prantzos, N
  • Journal Title: AIP Conference Proceedings in : ORIGIN OF MATTER AND EVOLUTION OF GALAXIES 2013 (ed. S. Jeong , N. Imai , H. Miyatake & T. Kajino) Volume: Vol. 1594 Pages: 46
  • DOI: 10.1063/1.4874043
  • Peer Reviewed
• [Journal Article] Diversity of abundance patterns of neutron-capture elements in very metal-poor stars (2014)
  • Author(s): Aoki, M., Aoki, W., Ishimaru, Y., & Wanajo, S
  • Journal Title: AIP Conference Proceedings in : ORIGIN OF MATTER AND EVOLUTION OF GALAXIES 2013 (ed. S. Jeong , N. Imai , H. Miyatake & T. Kajino) Volume: Vol. 1594 Pages: 123
  • DOI: 10.1063/1.4874056
  • Peer Reviewed
• [Journal Article] Constraints on the weak r-process : Abundance of Palladium in metal poor stars (2010)
  • Author(s): François, P., Wanajo, S., Prantzos, N., James, G., Ishimaru, Y., Aoki, W., & Honda, S
  • Journal Title: Proceedings of the 11th Symposium on Nuclei in the Cosmos, PoS(NIC XI) Volume: 264 Pages: 4
  • URL: http://pos.sissa.it/archive/conferences/100/264/NIC%20XI_264.pdf
  • Peer Reviewed
• [Journal Article] Galactic Chemical Evolution and Origin of r-Process Elements (2009)
  • Author(s): Ishimaru, Y., Wanajo, S
  • Journal Title: American Physical Society, 3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan Volume: abstract #CG.008 Pages: 13-17
• [Presentation] 中性子星合体はrプロセスの起源か:階層的構造形成論に基づく化学進化にみる (2014)
  • Author(s): 石丸友里, 和南城伸也, N. Prantzos
  • Organizer: 日本天文学会2014年春季年会
  • Place of Presentation: 国際基督教大学(東京都三鷹市)
  • Year and Date: 20140319-22
• [Presentation] 金属欠乏星の中性子捕獲元素組成の解析 (2014)
  • Author(s): 青木みさ,石丸友里, 青木和光, 和南城伸也
  • Organizer: 日本天文学会2014年春季年会
  • Place of Presentation: 国際基督教大学(東京都三鷹市)
  • Year and Date: 20140319-22
• [Presentation] 三次元非一様化学進化モデルと鉄より重い元素の起源 (2014)
  • Author(s): 荒尾幸絵,石丸友里, 和南城伸也
  • Organizer: 日本天文学会2014年春季年会
  • Place of Presentation: 国際基督教大学(東京都三鷹市)
  • Year and Date: 20140319-22
• [Presentation] 矮小銀河の形態による化学進化の違い (2014)
  • Author(s): 深川奈桜,石丸友里
  • Organizer: 日本天文学会2014年春季年会
  • Place of Presentation: 国際基督教大学(東京都三鷹市)
  • Year and Date: 20140319-22
• [Presentation] Origins of light trans-Fe and r-process elements deduced from chemical evolution of the Galactic halo (2013)
  • Author(s): Ishimaru, Y., Wanajo, S., Prantzos, N
  • Organizer: The 12th international symposium on Origin of Matter and Evolution of Galaxies (OMEG12)
  • Place of Presentation: Tsukuba, Japan
  • Year and Date: 20131118-22
• [Presentation] Diversity of abundance patterns of neutron-capture elements in very metal-poor stars (2013)
  • Author(s): Aoki, M., Aoki, W., Wanajo, S., Ishimaru, Y
  • Organizer: The 12th international symposium on Origin of Matter and Evolution of Galaxies (OMEG12)
  • Place of Presentation: Tsukuba, Japan
  • Year and Date: 20131118-22
• [Presentation] 中性子星合体はrプロセスの起源か:銀河系の化学進化にみる (2013)
  • Author(s): 石丸友里, 和南城伸也, N. Prantzos
  • Organizer: 日本天文学会2013年秋季年会
  • Place of Presentation: 東北大学(宮城県仙台市)
  • Year and Date: 20130910-12
• [Presentation] 三次元非一様化学進化モデルの構築と亜鉛の起源 (2013)
  • Author(s): 荒尾幸絵, 石丸友里, 和南城伸也
  • Organizer: 日本天文学会2013年秋季年会
  • Place of Presentation: 東北大学(宮城県仙台市)
  • Year and Date: 20130910-12
• [Presentation] Chemical evolution of the Galaxy and origin of r-process (2012)
  • Author(s): Ishimaru,Y., Wanajo, S., Prantzos, N
  • Organizer: 第1回国立天文台・滞在型研究員(セミナー実施型)国際集会:「元素の起源と宇宙の化学進化―rプロセスに焦点をあてて」/ Element Genesis and Cosmic Chemical Evolution
  • Place of Presentation: 理化学研究所(埼玉県和光市)
  • Year and Date: 20121017-19
• [Presentation] 階層的銀河系形成説によるrプロセス元素の非一様化学進化 (2012)
  • Author(s): 石丸友里, 和南城伸也, N. Prantzos
  • Organizer: 日本天文学会2012年秋季年会
  • Place of Presentation: 大分大学旦野原キャンパス(大分市)
  • Year and Date: 20120919-21
• [Presentation] Evolution of r-process elements in the framework of the hierarchical formation of the Milky Way (2012)
  • Author(s): Ishimaru, Y., Wanajo, S., & Prantzos, N
  • Organizer: IAP-Subaru Joint International Conference : Stellar populations across Cosmic Times
  • Place of Presentation: Institut d'Astrophysique de Paris, Paris, France
  • Year and Date: 20120625-29
  • Invited
• [Presentation] Enrichment of r-process elements in the early Galaxy (2012)
  • Author(s): Ishimaru, Y., Wanajo, S., & Prantzos, N
  • Organizer: 9th Russbach Workshop on Nuclear Astrophysics
  • Place of Presentation: Russbach, Austria
  • Year and Date: 20120312-16
• [Presentation] 階層的構造形成に基づく銀河系化学進化とrプロセス元素の起源 (2011)
  • Author(s): 石丸友里, 和南城伸也, N. Prantzos
  • Organizer: 日本天文学会2011年秋季年会
  • Place of Presentation: 鹿児島大学(鹿児島市)
  • Year and Date: 20110919-22
• [Presentation] 階層的銀河形成に基づくrプロセス元素の起源 (2011)
  • Author(s): 石丸友里, 和南城伸也, N. Prantzos
  • Organizer: 研究会「恒星進化・星形成から探る銀河の形成・進化の研究-宇宙最初の星から太陽系形成まで」
  • Place of Presentation: 北海道大学(札幌市)
  • Year and Date: 20110302-04
• [Presentation] Enrichment of the r-process elements in the sub-halos as building blocks of the Milky Way halo (2010)
  • Author(s): Ishimaru, Y., Wanajo, S., & Prantzos, N
  • Organizer: 11th Symposium on Nuclei in the Cosmos (NIC XI)
  • Place of Presentation: Heidelberg, Germany
  • Year and Date: 20100719-23
• [Presentation] Constraints on the weak r-process : Abundance of Palladium in metal poor stars (2010)
  • Author(s): François, P., Wanajo, S., Prantzos, N., James, G., Ishimaru, Y., Aoki, W., & Honda, S
  • Organizer: 11th Symposium on Nuclei in the Cosmos (NIC XI)
  • Place of Presentation: Heidelberg, Germany
  • Year and Date: 20100719-23
• [Presentation] Galactic chemical evolution and origin of r-process elements (2010)
  • Author(s): Ishimaru, Y., Wanajo, S., & Prantzos, N
  • Organizer: 15th Workshop on "Nuclear Astrophysics"
  • Place of Presentation: Ringberg Castle (Kreuth, Germany)
  • Year and Date: 20100322-27
• [Presentation] Galactic Chemical Evolution and Origin of r-Process Elements (2009)
  • Author(s): Ishimaru, Y., & Wanajo, S
  • Organizer: 3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Place of Presentation: Waikoloa, Hawaii, USA
  • Year and Date: 20091013-17