PhD position: Origin of the Elements – Stellar Nucleosynthesis

Most elements heavier than hydrogen and helium as made in stars and released in their final evolution stages by stellar winds or by a terminal supernova explosion.  Massive stars, those that explode as core collapse supernovae at the end of their lives, are responsible for about half of the heavy elements.  They live for short times and release their freshly-synthesised heavy elements swiftly.  Their nucleosynthesis proceeds by hydrostatic burning as well as during the supernova explosion.  Recent studies, however, have shown that how much they produce of each element, and whether they explode at all or just collapse to a black hole, may vastly vary from star to star. This can be driven not only by chaotic behaviour of stellar structure due to turbulence – even seemingly similar stars may end up differently -, but also by other factors, such as their initial composition, rotation, magnetic fields, or whether they are in a binary star system.

If we endeavour to understand the origin of the elements, including being able to discern different models for the evolution of galaxies or even scenarios for the formation and origins of our own solar system, we need to know not only the outcomes of select models, but to have a good statics of outcomes, their distributions, and outliers – some elements and isotopes are rate, hence their production could well be dominates by a few sources.  Beyond nucleosynthesis, different outcomes of stellar evolution also affect observational supernovae and their statistics, and is directly connected to what remnants they make, such as neutron stars and black holes.

One of the forefront question of current astronomy is the nature of the first stars in the universe, in particular, what is their masses, what elements did they produce, and how did they drive the formation and evolution of the first (small) galaxies.  We do observe old stars in our own galaxy, long-lived low-mass stars, some of them likely dating back to the epoch after the first stars and presumably formed, in part, of the debris of the first generation of stars, conserving what they produce frozen-in as time capsule.  We observe a large variety of abundance patters in such stars that call for interpretation (and surely have inspired abundant theories in publications in the most distinguished journals) but, e.g., to make a safe call whether a specific pattern has to come from contributions of several stars or whether it can be attributed to a single star, or how contrived theories are requited to explain our observations, depends, again, on having an adequate, extended, and statistically representative basis of stellar evolution and nucleosynthesis outcomes of the first generation of stars.

We invite applications for PhD projects to model the nucleosynthesis in massive stars from the first generation to the present.  As building blocks of a thesis, this includes projects in depth and breadth, but also focus on specific aspects such as rotation or binary star evolution, as well as modelling sophisticated comparison to observation data.

References:

Mueller et al. https://ui.adsabs.harvard.edu/abs/2016MNRAS.460..742M

Keller et al. https://ui.adsabs.harvard.edu/abs/2014Natur.506..463K

Heger et al. https://ui.adsabs.harvard.edu/abs/2010ApJ…724..341H