The origin of short-lived nuclides in the early solar system: implications for the assembly of terrestrial bodies

短暂的同位素系统在限制早期太阳系过程的时间尺度方面发挥着关键作用。它们还可能识别太阳星云中的恒星物质来源，并为星云坍塌提供一种机制。在所有这些方面，寿命非常短的26Al和60Fe(半衰期分别为0.75和1.5 My)提供的限制是关键。此外，作为主要的难熔元素，这些已灭绝的同位素曾构成正在吸积的类地行星的重要组成部分，并为推动行星分化提供了重要的早期热源。最近在Fe-Ni系统中的工作产生了诱人的数据，但在解释这些短暂的系统时，突出了从初始非均质性到去卷积时间的长期问题。在这项提案中，我们将通过结合新的高精度技术来明确解决这些问题，这些新技术用于分析同一陨石对象(计算机辅助陨石和球粒陨石)的铁镍、铝镁和铀铅。因此，我们将确定绝对U-Pb测年样品的初始60Fe和26Al，并检查不同陨石群之间是否存在差异。这将使我们能够确定任何星云不均一性的大小，评估其原因，并有力地重新评估早期太阳系的年代学。

Short-lived isotope systems play a critical role in constraining the timescales of early solar system processes. They also potentially finger-print the stellar sources of material in the solar nebular and provide a mechanism for nebular collapse. In all these respects the constraints provided by the very short lived 26Al and 60Fe (with half-lives 0.75 and 1.5My respectively) are key. Furthermore, as major, refractory elements, these extinct isotopes once constituted an essential part of the accreting terrestrial planets and provided a significant early heat source to drive planetary differentiation. Recent work in the Fe-Ni system yield tantalising data, but highlight perennial problems in deconvolving time from initial heterogeneity when interpretting these short-lived systems. In this proposal we will explicitly address these issues by combining new high precision techniques in analysis of Fe-Ni, Al-Mg and U-Pb on same meteoritical objects (CAI and chondrules). We will thus determine the initial 60Fe and 26Al for samples absolutely dated by U-Pb and examine if this differs between meteorites groups. This will allow us to determine the magnitude of any nebular heterogeneity, assess its causes and robustly re-evaluate the chronology of the early solar system.