2025-12-11 東京大学,京都大学,福井県立大学
「宇宙線浴 (Immersion）」メカニズムの概念図
超新星爆発の衝撃波が、原始太陽系円盤全体を包み込み、内部で核反応を引き起こす様子
＜関連情報＞
- https://www.u-tokyo.ac.jp/focus/ja/press/z0109_00189.html
- https://www.u-tokyo.ac.jp/content/400275761.pdf
- https://www.science.org/doi/10.1126/sciadv.adx7892
過去の超新星爆発の宇宙線浴が地球のような惑星を生み出す Cosmic-ray bath in a past supernova gives birth to Earth-like planets
Ryo Sawada, Hiroyuki Kurokawa, Yudai Suwa, Tetsuo Taki, […] , and Ataru Tanikawa
Science Advances Published:10 Dec 2025
DOI:https://doi.org/10.1126/sciadv.adx7892
Abstract
A key question in astronomy is how ubiquitous Earth-like rocky planets are. The formation of terrestrial planets in our Solar System was strongly influenced by the radioactive decay heat of short-lived radionuclides (SLRs), particularly 26Al (aluminum-26), likely delivered from nearby supernovae. However, current models struggle to reproduce the abundance of SLRs inferred from meteorite analysis without destroying the protosolar disk. We propose the “immersion” mechanism, where cosmic-ray nucleosynthesis in a supernova shockwave reproduces estimated SLR abundances at a supernova distance (~1 parsec), preserving the disk. We estimate that solar mass stars in star clusters typically experience at least one such supernova within 1 parsec, supporting the feasibility of this scenario. This suggests that Solar System–like SLR abundances and terrestrial planet formation are more common than previously thought.
