Alexander Zarebski

“To enhance our understanding of early magnetic field generation in both Earth-like and exoplanetary settings, with broader implications for planetary habitability.”

PhD project title:

Investigating the Role of Basal Magma Oceans in the Formation of Exoplanetary Magnetic Fields.

Alexander Zarebski

Project description:

The concept of a Basal Magma Ocean (BMO) has been proposed to explain the presence of large low-shear velocity provinces (LLSVPs) and ultra-low velocity zones (ULVZs) at the Earth’s core-mantle boundary (CMB) (Braithwaite, 2022). These BMOs, potentially formed on Earth and other rocky planets, are hypothesised to remain stable for billions of years, possibly contributing to the early generation of planetary magnetic fields (Ziegler, 2013).
Formation of a BMO involves the compaction of silicate liquids at high pressures, leading to the descent of Fe-rich droplets, which eventually crystallise and form a stable layer at the mantle’s base (Labrosse, 2007).
For rocky super-Earths, the presence of larger, hotter interiors could sustain long-lived BMOs, potentially driving magnetic fields through dynamo action in silicate melts under extreme pressure-temperature conditions (Stixrude, 2014). The interaction between the BMO and core dynamics may generate complex magnetic fields, influencing planetary habitability through magnetosphere formation and atmospheric retention.
This project will explore the conditions of long-lived BMOs and how this may affect magnetic field generation and evolution, particularly in ultrashort period (USP) rocky planets. First, we will use geodynamic models to simulate core-mantle interactions and then magnetohydrodynamics to model magnetic dynamo processes. These findings will enhance our understanding of early magnetic field generation in both Earth-like and exoplanetary settings, with broader implications for planetary habitability.

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