Title: The oldest magnetic record in our Solar System

Speaker: Jay Shah (Imperial College London, Natural History Museum, London, UK)

Abstract:

Chondritic meteorites largely formed 4.6 billion years ago, and can range from being metamorphosed as a result of processing on their asteroid parent bodies to entirely unaltered since their formation in the protoplanetary disk. The magnetic grains within these meteorites can potentially record and retain the magnetic conditions on the parent body and the conditions in the protoplanetary disk during the formation of our planetary system. However, the complex history of these meteorites can make their magnetic records difficult to interpret, and their age prompts the question of whether a magnetic remanence can be retained for so long.

To help identify the origin of the magnetic remanence, I present a new method for the palaeomagnetic conglomerate test that uses micro-CT scans to accurately mutually orient chondrules from chondrites. When applied to meteorites Vigarano (CV3) and Bjurböle (L/LL4), a more in-depth understanding of parent body processing is achieved that provides evidence for magnetic dynamo activity on their parent bodies.

To determine whether magnetic remanence can be retained from the early Solar System, I present a demonstration of the high thermal stability of single and multi-vortex kamacite grains from the meteorite Bishunpur (LL3.1). In-situ temperature-dependent nanometric magnetic measurements using electron holography and numerical micromagnetic energy barrier calculations find that the majority of kamacite grains in dusty olivines are capable of retaining magnetic field information from the early Solar System, a key finding in our quest to understand the formation of our Solar System.