Noble gas isotope analysis for individual presolar grain to study environment of interstellar material

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04036
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Hokkaido University
• Principal Investigator: BAJO KEN-ICHI 北海道大学, 理学研究院, 助教 (70624758)
• Co-Investigator(Kenkyū-buntansha): 川崎 教行 北海道大学, 理学研究院, 准教授 (50770278)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 希ガス / 深さ方向分析 / プレソーラー粒子 / 恒星風

Outline of Final Research Achievements

Presolar silicon carbide (SiC) is known to form around carbon and AGB stars. These stars have an isotopic composition different from that of the Solar System. The SiC formed in this region should have been exposed to stellar winds and interstellar galactic cosmic rays. Depth profiles of noble gases for the SiC can reveal the implantation of the stellar wind. The depth profiles reflect the energy of the stellar winds.
In this study, depth profiles of He in presolar SiC were analysed. The results show a depth profile of He. This indicates that the stellar wind He is implanted in the SiC. The energy of the stellar wind estimated from the He profile is 10-20 keV.

Free Research Field

同位体宇宙化学

Academic Significance and Societal Importance of the Research Achievements

本研究により，プレソーラーSiCのHeの起源は恒星風によるイオン注入であることが分かった．本研究で用いた同位体ナノスコープによって空間分解能10nmレベルの深さ方向分析に成功した．このことによってはじめてSiC粒子の極めて表層に濃縮する恒星風起源Heを検出することができた．AGB星が放出している恒星風と，太陽風との違いを調べていくことで，太陽系外の恒星の様子を物質科学的に明らかにできると考えている．