Stars, planets and explosions: nucleosynthesis beyond binaries

This PhD project will explore how hierarchical stellar systems – triples and quadruples, together with planets orbiting single and multiple stars – reshape stellar evolution, transient phenomena and the chemical enrichment of galaxies. Most population-synthesis work treats stars as single or binary systems, yet higher-order multiplicity modifies interactions through mass transfer, mergers including compact objects, common-envelope evolution, supernova progenitors and orbital dynamics. The student will investigate how these effects change the rates and nucleosynthetic yields of type Ia and core-collapse supernovae, novae and related transients, and how they feed through into stellar populations, chemically peculiar stars and galactic chemical evolution. The results will feed back into the HAYDN satellite project.

A central part of the project is development of the binary_c population-synthesis framework, which already combines rapid stellar and binary evolution with nucleosynthesis, supernova and nova yield prescriptions, with support for orbiting objects and circumbinary discs. The student will extend this framework to include triple- and quadruple-star evolution, building physically motivated models of how additional companions and planets alter mass loss, accretion, orbital evolution and stellar outcomes. The project will also examine how planets can affect the apparent chemical signatures of stars, for example through planet engulfment during red-giant evolution or enrichment of white dwarfs by accreted planetary material, with implications for how galactic chemical evolution is inferred from stellar abundances.

Because direct integration of large numbers of hierarchical encounters is computationally prohibitive, the project will also use and develop machine-learning emulators for triple and quadruple interactions, enabling fast but accurate treatment inside population-synthesis calculations. The resulting tools will make it possible to predict observable signatures of higher-order multiplicity across stellar populations, from unusual abundance patterns and exotic supernova channels to the survival, migration and habitability of planets in evolving stellar systems.

You will need to meet the minimum entry requirements for our Physics PhD programme.

Open to candidates who pay UK/home rate fees. See UKCISA for further information.