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

在太阳形成后的~5Myr期间，我们的太阳系被认为经历了一系列巨大的变化，因为它迅速从一个由尘埃和气体组成的混乱云转变为由原行星和小行星组成的有组织的圆盘[1]。在这一短时间内，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。据预测，质量和角动量转移是由坍塌星云中存在的古老磁场控制的，然而，对其他太阳系中这些磁场的天文测量只对它们的性质提供了微弱的限制。因此，对太阳系最初5MyR内形成的陨石的磁测量可能会对这些关键磁场的寿命、强度和演化提供独特的限制[2]。此外，我们还没有从另一个太阳系的天体上直接测量到年轻的内部产生的行星磁场。因此，古代陆地样品的免费磁性测量可以为原始地球的热演化和吸积提供关键限制。在这个项目中，学生将专注于使用各种尖端技术(主要是古地磁技术和可能的免费地球化学测量)，对一系列陨石和古代陆地样品中不同成分携带的磁性进行实验研究。理想情况下，这些数据将伴随着建模，以帮助解释它们。总体目标将是可靠地推断这些样品所经历的古代磁场的性质，并利用观测结果更好地了解原始地球、小行星、太阳星云和太阳的早期演化。这名学生将加入一个国际研究团队，共同研究这一问题，并有可能延长对麻省理工学院、哈佛大学和/或劳伦斯·伯克利实验室的访问，以获取数据。学生将使用传统的和开创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测量，以及这些样品中微纳尺度磁性材料的新型磁性显微镜(超导量子干涉装置、磁隧道结、量子钻石显微镜[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性显微镜的磁性表征。理想情况下，学生还将执行行星体内和太阳星云内的热演化和磁场产生模型，以最好地解释他们的观测结果。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.