Physik-Department, Technische Universität München, 85748 Garching, Germany.
Excellence Cluster Universe, 85748 Garching, Germany.
Phys Rev Lett. 2019 Aug 16;123(7):072701. doi: 10.1103/PhysRevLett.123.072701.
Earth is constantly bombarded with extraterrestrial dust containing invaluable information about extraterrestrial processes, such as structure formation by stellar explosions or nucleosynthesis, which could be traced back by long-lived radionuclides. Here, we report the very first detection of a recent ^{60}Fe influx onto Earth by analyzing 500 kg of snow from Antarctica by accelerator mass spectrometry. By the measurement of the cosmogenically produced radionuclide ^{53}Mn, an atomic ratio of ^{60}Fe/^{53}Mn=0.017 was found, significantly above cosmogenic production. After elimination of possible terrestrial sources, such as global fallout, the excess of ^{60}Fe could only be attributed to interstellar ^{60}Fe which might originate from the solar neighborhood.
地球不断受到含有宝贵外星过程信息的外星尘埃的轰炸，例如恒星爆炸或核合成引起的结构形成，可以通过长寿命放射性核素追踪到这些过程。在这里，我们通过加速器质谱分析 500 公斤来自南极洲的雪，首次报告了最近地球 ^{60}Fe 流入的情况。通过测量宇宙成因放射性核素 ^{53}Mn，发现 ^{60}Fe/^{53}Mn 的原子比为 0.017，明显高于宇宙成因产生的比例。在排除了可能的地球来源，如全球沉降物之后， ^{60}Fe 的过剩只能归因于星际 ^{60}Fe，它可能来自太阳系附近。
