Stellar and planetary astrophysics

Exploring chemical evolution and origin of elements

Research projects in this theme also look at stellar structure, clusters and populations, galactic archaeology and formation as well as planet formation and exoplanet detection.

Typical facilities used by our group are:

• bespoke surveys like Galah at the Anglo-Australian Telescope
• European Southern Observatory telescopes, such as the Very Large Telescope
• space telescopes like Gaia or the James Webb Space Telescope
• the Vista Survey of the Magellanic Clouds undertaken with the ESO/VISTA telescope.

Learn more about the projects we are undertaking, the researchers engaged in them and who you can contact to get involved.

Cosmic alchemy: Evolved stars as probes for stellar nucleosynthesis

How the chemical elements in the universe are synthesised is one of the defining questions of astrophysics.

Low- and intermediate-mass stars are major contributors to the chemical enrichment of galaxies, yet the nucleosynthesis pathways operating inside them remain poorly understood. Critical constraints come from the short-lived post-asymptotic giant branch (post-AGB) phase, when stellar evolution exposes material processed in the stellar interior and preserves a direct record of the star’s nucleosynthetic history.

This project will use multi-technique observations of post-AGB stars obtained with leading facilities, including:

• complementary international surveys
• the Atacama Large Millimetre/submillimetre Array
• the CRIRES+ spectrograph on the European Southern Observatory’s Very Large Telescope (VLT)
• the James Webb Space Telescope.

By combining high-resolution spectroscopic observations in optical and infrared regimes with interferometric imaging, the project will deliver a homogeneous chemical characterisation of evolved stars and constrain the physical processes responsible for element production in low- and intermediate-mass stars.

To get involved in this project, contact: Devika Kamath

Finding Earth's neighbours with extremely precise radial velocities

The first exoplanets were discovered by the radial velocity method, measuring the tiny Doppler shift in their star's spectral lines as it wobbles back and forth under the planet's gravity. Today these instruments should almost be stable enough to pick up exo-Earths – but we are limited not by hardware, but by an imperfect knowledge of how stars vary.

In this project we aim to machine-learn models of stellar spectra and how they can change with stellar magnetism, and use these better models to analyse the data from the world's leading exoplanet spectrographs NEID and HPF.

Working with Associate Professor Christian Schwab, who designed these two instruments, with Associate Professor Benjamin Pope on the stats and machine learning and other students and postdocs, you will build and apply better data analysis software to pick up the tiny signals of Earth-mass planets out of these data and find some of the first rocky worlds around neighbouring stars.

To get involved in this project, contact: Benjamin Pope

Imaging exoplanets with the James Webb Space Telescope

To take direct images of exoplanets means pushing instruments to their limits – even NASA's flagship observatory, the James Webb Space Telescope (JWST), demands very sophisticated data analysis to see the faint specks of planets next to bright stars.

Our team has recently demonstrated a totally new approach to data analysis with one of the JWST cameras, achieving the telescope's highest resolution images by combining machine learning with physical models of the camera.

If you like Python and you like imaging science, this is a PhD with considerable scope: We want to extend these ideas to all the other observing modes with JWST and the next generation of instruments on Roman and Lazuli. We will combine physics models, neural networks and modern Bayesian statistics to dig faint planets out of the noise and measure their properties, paving the way for the long-term search for alien life.

To get involved in this project, contact: Benjamin Pope

Multi-wavelength high-angular-resolution imaging of second-generation planet-forming discs

Can planets form only around young stars or can dying stars get a second chance to build planets?

Planets are thought to form in dusty discs around young stars. However, recent discoveries suggest that dying binary stars may create a second generation of planet-forming environments, when gas and dust expelled late in stellar life become trapped in stable circumbinary discs.

Using high-angular-resolution observations from world-leading facilities – including Very Large Telescope/SPHERE polarimetric imaging, VLTI interferometry at the European Southern Observatory and the Atacama Large Millimetre/submillimetre Array (ALMA) – this project will map the structure and dust properties of these evolved discs, revealing whether dying stars can recreate the conditions needed for planet formation.

The project will suit a student interested in observational astrophysics, planet formation and advanced imaging techniques.

To get involved in this project, contact: Devika Kamath

Stellar variability: Redefining the Milky Way’s fundamentals

We will exploit the most extensive and statistically complete catalogue of 572,338 periodic variable stars in the Milky Way to robustly quantify our galaxy’s 3D mass/stellar distribution.

We will conclusively determine the time evolution of the Milky Way’s spiral arms and of its warped stellar disk to distances two to three times further from the Galaxy’s centre than our Sun. Accurately knowing the Milky Way’s structure is fundamental, since it is the benchmark by which we measure external galaxies.

The research project will also set the standard for stellar structure studies and analyses of gravitational-wave source properties.

To get involved in this project, contact: Richard de Grijs

Using dying stars to reveal the origin of elemental isotopes in the universe

How the elements in the universe are synthesised is one of the defining questions of astrophysics.

Low- and intermediate-mass (LIM) stars are key contributors to the chemical enrichment of their host galaxies. However, understanding how they produce their elements remains an unsolved problem.

Using high-resolution spectra of post-AGB stars – obtained from facilities such as the 8-metre Very Large Telescopes at the European Southern Observatory, the Australian-led million-star GALactic Archaeology with HERMES (GALAH) survey and other international surveys – this project will conduct a comprehensive and homogeneous chemical analysis, finally revealing the process of element production in LIM stars.

To get involved in this project, contact: Devika Kamath