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Early planetesimal melting from an age of 4.5662 Gyr for differentiated meteorites

机译：年龄为4.5662 Gyr的早期行星状星体，用于分化的陨石

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Long- and short-lived radioactive isotopes and their daughter products in meteorites are chronometers that can test models for Solar System formation(1,2). Differentiated meteorites come from parent bodies that were once molten and separated into metal cores and silicate mantles. Mineral ages for these meteorites, however, are typically younger than age constraints for planetesimal differentiation(3-5). Such young ages indicate that the energy required to melt their parent bodies could not have come from the most likely heat source(6) - radioactive decay of short-lived nuclides (Al-26 and Fe-60) injected from a nearby supernova - because these would have largely decayed by the time of melting. Here we report an age of 4.5662 +/- 0.0001 billion years ( based on Pb - Pb dating) for basaltic angrites, which is only 1Myr younger than the currently accepted minimum age of the Solar System(7) and corresponds to a time when Al-26 and Fe-60 decay could have triggered planetesimal melting. Small Mg-26 excesses in bulk angrite samples confirm that Al-26 decay contributed to the melting of their parent body. These results indicate that the accretion of differentiated planetesimals pre-dated that of undifferentiated planetesimals, and reveals the minimum Solar System age to be 4.5695 +/- 0.0002 billion years.
机译：陨石中长寿命和短寿命放射性同位素及其子产物都是可以测试太阳系形成模型的天文钟（1,2）。分化的陨石来自母体，它们曾经被熔融并分离成金属核和硅酸盐地幔。然而，这些陨石的矿物年龄通常比行星年龄分化的年龄限制年轻（3-5）。如此年轻的年龄表明，熔化其母体所需的能量不可能来自最可能的热源（6）-从附近的超新星注入的短寿命核素（Al-26和Fe-60）的放射性衰变-因为这些在融化时会大大衰减。在这里，我们报道了玄武质天使的年龄为4.5662 +/- 0.0001亿年（基于Pb-Pb测年），仅比当前公认的太阳系最低年龄年轻7毫秒（7），并且对应于Al -26和Fe-60的衰变可能触发了行星的熔化。块状角铁样品中少量的Mg-26过量证实了Al-26的腐烂有助于其母体的熔化。这些结果表明，分化的小行星的积聚早于未分化的小行星的积聚，并且揭示出太阳系的最小年龄为4.5695 +/- 0.0002亿年。

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