PhD project 2026

I am advertising a PhD project to commence in Autumn 2026. You can find the description of the project here. Please feel free to contact me if you would like to discuss the project in more detail.

Convection and Accretion in White Dwarf Atmospheres: A Multi-Wavelength and 3D Simulation Approach

Summary: In this project, you will develop advanced computational methods and multi-wavelength observational techniques to investigate the complex phenomena of stellar convection, and accretion in ancient planetary systems.

White dwarfs—the compact remnants left behind by stars like the Sun after they exhaust their fuel—provide a unique window into the composition of exoplanetary material that cannot be directly accessed for planets orbiting main-sequence stars. When a star becomes a white dwarf, the resulting gravitational rearrangement of the planetary system can cause asteroids, moons, and even planets to be disrupted and accreted onto the white dwarf’s surface over billions of years. This process leaves observable signatures—specifically, traces of metals in the otherwise pure atmospheres of white dwarfs—that allow us to directly measure the bulk composition of exoplanetary bodies, including elements vital to understanding planetary formation. Thanks to the success of the European Space Agency’s Gaia mission, more than 300,000 high-confidence white dwarf candidates have been identified. With the advent of next-generation multi-object spectroscopic surveys, which will vastly expand both the quantity and quality of white dwarf data, there is an urgent need for improved theoretical and numerical models, especially to simulate complex processes such as convection and mixing in white dwarf atmospheres. These models will be essential for accurately interpreting the forthcoming wealth of observational data and advancing our knowledge of the origin and evolution of planetary systems.

The aim of this project is to develop pioneering 3D radiation-hydrodynamic simulations to advance our understanding of white dwarf atmospheres and the planetary debris they reveal. It has become clear that the treatment of convection in white dwarf atmospheres significantly affects inferred properties such as accretion rates, debris masses, and the detailed composition of evolved planetary systems. This project will utilise the state-of-the-art 3D RHD code CO5BOLD to develop a robust physical model of white dwarf convection zones, including investigations of how their properties dependon factors such as cooling age and magnetic field strength. These models will allow us to explore planetary systems dating back to the early Universe. Tackling substantial computational challenges, the project will leverage high-performance computing and innovative wave-filtering techniques to isolate convective phenomena. The resulting simulations will underpin the development of the first analytic model of convective overshoot, leading to much greater accuracy in white dwarf structure and evolution models, and generating open-source grids for the astronomical community—crucial for making sense of data from large current and upcoming surveys. The project will also launch the first systematic 3D studies of magnetic field effects on convection and mixing, investigating how magnetism influences the detectability and distribution of accreted planetary material and recently observed variability in atmospheric metal lines. Overall, this work will transform the theoretical and observational tools available for using white dwarfs as natural laboratories for both planetary and stellar astrophysics. The outcomes will be directly relevant to ongoing and future multi-wavelength campaigns, including those utilizing the Hubble Space Telescope (UV), Chandra X-ray Observatory, and James Webb Space Telescope (infrared).