Stars and Planets

Stars are one of the basic building blocks of galaxies, while planets - including our own Earth - form naturally around stars. The formation and evolution of stars affects the chemical and energy budget of their host galaxies, and stellar remnants can be used to understand extreme states of matter and test theories of gravity.

With the rapid advances in our discovery of exoplanets, it is important that we understand planet formation if we are to make sense of the wide variety of planets being detected.  

Furthermore, the majority of stars are born within multiple systems (binaries or triples), and many of these are born in star clusters. For a star in a binary, interaction with the companion star can include processes such as mass exchange and gravitational wave emission, while in the dense stellar environment of a star cluster, which can be a factor of 10 million greater than the stellar density of the solar neighbourhood, physical collisions and close encounters between stars are a reality of life.

Such activity can radically alter the fates of stars compared to predictions from standard evolution theory and lead to the formation of exotic stars or binaries.  

A key area of research focus is star and planet formation, including the formation of molecular clouds, the dynamics and evolution of disks around young single and binary stars, the early stages of planet growth from microns to metres, and the effects of planets on the evolution of protostellar disks.

Our astronomers use a variety of observatories, including the Australia Telescope Compact Array millimetre interferometer, the Submillimeter Array, NANTEN2, APEX, Gemini, VLT and the Hubble Space Telescope to probe these systems.  

To understand how stars evolve in all manner of environments, we investigate the detailed evolution of individual stars and binaries, the statistics of large binary populations and the combination of stellar, binary and dynamical evolution within a star cluster environment.

Topics of interest range from the destruction of star clusters to the physics of supernovae, determining the astrophysical sources of gravitational waves and the formation of exotic stars in general.  

We have rapid stellar and binary evolution codes for synthesising large stellar populations, multi-dimensional hydrodynamical codes for modelling the crucial seconds after a supernova explosion and an N-body code for performing realistic simulations of stellar clusters.