MI2023 - 01 James Bryson: A revised intensity of the protoplanetary disk magnetic field
Channel: MagNetZ
Date: 2023-01-16

Magnetic Interactions 2023 conference at the University of Cambridge
Session 1: Solar System and Asteroid Magnetism

Title: A revised intensity of the protoplanetary disk magnetic field from the Winchcombe meteorite
Author: James Bryson from the University of Oxford, UK

Several features governed the behaviour of our protoplanetary disk and its transformation into a system of planetary bodies, one of which was its vast magnetic field. Unique constraints on the properties of this field can be gleaned from paleomagnetic measurements of certain meteorites. Here, we report measurements of the magnetic remanence carried by the recent CM chondrite fall Winchcombe with the aim of constructing the most complete model to date of the disk field in the outer solar system.
We find that the interior of Winchcombe carries a stable, pre-terrestrial magnetisation that likely dates from the period of aqueous alteration of the CM chondrite parent body. This remanence corresponds to a paleointensity of 31 ± 17 μT accounting for the average effect of parent body rotation. Winchcombe is rich in framboids and plaquettes of magnetite, which formed via precipitation from a fluid. This contrasts most other CM chondrites, which consist predominantly of magnetite grains that form via pseudomorphic replacement of metal. Accounting for the possible differences in recording efficiencies of these morphologies of magnetite, we argue that the reported paleointensities from all CM chondrites to date underestimate the disk field intensity in the outer solar system. Utilising all these values, we calculate a revised estimate of this intensity of ~78 μT. This value is consistent with two independent estimates from recent studies, which collectively suggest that the disk field could have played a larger role in shaping the dynamics of the disk in the outer solar system than previously thought.

-----------------------------------------------------------

00:00 - Intro
00:25 - Presentation
19:35 - Questions