The evolution of the early solar system and early Earth inferred from paleomagnetism

在太阳形成后的500万年里，我们的太阳系被认为经历了一系列巨大的转变，因为它迅速从一个混乱的尘埃和气体云转变为一个有组织的原行星和小行星盘[1]。在这一短暂的时期内，太阳系内的质量和角动量的转移被认为在这一过程中发挥了核心作用。质量和角动量的转移被预测是由坍缩星云中存在的古老磁场控制的，然而在其他太阳系中对这些磁场的天文测量只提供了对它们性质的微弱限制。因此，对太阳系前500万年内形成的陨石进行磁性测量，可以对这些关键磁场的寿命、强度和演变提供独特的限制[2]。此外，我们还没有直接测量到另一个太阳系中的一个天体内部产生的年轻行星场。因此，对古地球样品的补充磁性测量可以为原始地球的热演化和吸积提供关键的限制。在这个项目中，学生将专注于使用各种尖端技术（主要是古地磁技术，可能有补充的地球化学测量）对一系列陨石和古地球样品中不同成分所携带的磁性进行实验研究。理想的情况是，这些数据将伴随着建模，以协助其解释。总体目标是可靠地推断这些样本经历的古代磁场的性质，并利用观测结果更好地了解原地球、小行星、太阳星云和太阳的早期演变。学生将加入一个国际研究团队，在这个问题上合作，并有可能延长访问麻省理工学院，哈佛和/或劳伦斯伯克利实验室获得数据。学生将使用传统和开拓性的古地磁技术来进行他们的研究。这些将包括大块样品的磁力测量，以及这些样品中微米至纳米级磁性材料的新型磁性显微镜（超导量子干涉器件，磁性隧道结，量子金刚石显微镜[3]和/或光电子发射显微镜）。学生将有机会决定研究的方向，包括在获取新数据的基础上开发这些开创性技术的可能性。数据采集将伴随着使用电子显微镜的结构表征和使用磁滞技术和磁显微镜的磁性表征。学生还将理想地执行行星体和太阳星云内的热演化和磁场生成模型，以最好地解释他们的观测结果。总之，这些方法的结合将提供对太阳系内早期磁活动的最严格的理解，并将为学生提供各种有用的实验和理论技能。

During the ~5 Myr following the formation of the Sun, our solar system is thought to have undergone a vast array of transformations as it quickly transitioned from a chaotic cloud of dust and gas into an organised disk of protoplanets and asteroids [1]. The transfer of mass and angular momentum within the solar system during this short period is believed to have played a central role in this process. Mass and angular momentum transfer have been predicted to have been governed by ancient magnetic fields present within the collapsing nebula, however astronomical measurements of these fields in other solar systems have only provided weak constraints on their properties. Magnetic measurements of meteorites that formed within the first 5 Myr of our solar system could therefore provide unique constraints on the lifetime, intensity and evolution of these crucial magnetic fields [2]. Furthermore, we are yet to obtain a direct measurement of a young internally-generated planetary field from a body in another solar system. Complimentary magnetic measurements of ancient terrestrial samples could therefore provide key constraints on the thermal evolution and accretion of the proto-Earth.In this project, the student will focus on the experimental study of the magnetism carried by different components within a range of meteorites and ancient terrestrial samples using a variety of cutting-edge techniques (predominantly paleomagnetic techniques with possible complimentary geochemical measurements). Ideally, these data will be accompanied by modelling to assist with their interpretation. The overall aim will be to reliably infer the properties of the ancient magnetic fields experienced by these samples and to use the observations to better understand the early evolution of the proto-Earth, asteroids, the solar nebula and the Sun. The student will be joining a international team of researchers working in collaboration on this problem, and there is the possibility of extended visits to MIT, Harvard and/or the Lawrence Berkeley Labs to obtain data. The student will use both traditional and pioneering paleomagnetic techniques to perform their research. These will include magnetometry of bulk samples, and novel magnetic microscopy (superconducting quantum interference device, magnetic tunnel junction, quantum diamond microscopy [3] and/or photoelectron emission microscopy) of micro- to nano-scale magnetic materials within these samples. There will be opportunities for the student to dictate the direction of the research, including the possibility of developing these pioneering techniques on top of the acquisition of novel data. Data acquisition will be accompanied by structural characterisation using electron microscopy and magnetic characterisation using magnetic hysteresis techniques and magnetic microscopies. The student will also ideally perform models of thermal evolution and magnetic field generation within planetary bodies and the solar nebula to best interpret their observations. Together, the combination of these approaches will provide the most rigorous understanding of early magnetic activity within the solar system and will provide the student with a variety of useful experimental and theoretical skills.