Activity of the proto-Sun revealed by multi-isotope analyses

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K17791
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geochemistry/Cosmochemistry
• Research Institution: Hokkaido University
• Principal Investigator: Bajo Ken-ichi 北海道大学, 理学研究院, 助教 (70624758)
• Research Collaborator: OKAZAKI Ryuji ; KAWASAKI Noriyuki
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 希ガス同位体 / 二次イオン質量分析 / 消滅核種 / 原始太陽 / 太陽宇宙線

Outline of Final Research Achievements

Ca-Al-rich inclusions (CAIs) in primitive chondrite meteorites contain detectable amounts of extinct nuclides such as 26Al (half life of 0.705 Myr) and 10Be (half life of 1.36 Myr). Especially, excess 10Be in CAIs, which would have been produced by solar cosmic ray (SCR) spallation, suggests that the proto-sun was more radiative than the present sun [1]. The intense SCRs could also produce 22Na, which decays to 22Ne (half life of 2.61 yr), from Mg, Al, and Si via spallation reaction. As sodium is a minor element composing melilite crystals of igneous CAIs [2, 3], excess 22Na could be found in CAIs formed at the early stage of the solar system evolution. However, such CAIs with excess 22Ne derived from 22Na have not been observed . Here, we report the excess in 22Ne in an igneous CAI from Allende CVox.

Free Research Field

同位体宇宙科学