Sydney Institute for Astronomy

Stars are the building blocks of the universe. At SIfA we use state-of-the-art techniques to study stars and their planetary systems. One of these techniques is high-resolution imaging which allows to study details on the finest possible scales.

The most critical events in the stellar life cycle are so remote that extremes of magnification are required to witness the key action. Another technique is asteroseismology, the study of oscillations in stars, which probes their interiors in exquisite detail. We use data from NASA’s Kepler and TESS missions to measure tiny changes in stellar brightness, which allow to measure their internal properties, and also to infer the properties of their planets. 

SIfA astronomers are leading major international projects to better understand how galaxies form and evolve. Galaxies are complex ecosystems of stars, gas, dark matter and central super-massive black holes that often play a key role in their evolution. SIfA is using new technology to build 3-dimensional pictures of galaxies with both radio and optical telescopes. The SAMI and Hector Galaxy Surveys use instruments developed at Sydney to measure spatially resolved optical spectroscopy of thousands of galaxies and examine their rich diversity. The ASKAP radio telescope allows us to break new ground in studying neutral hydrogen in distant galaxies.

Hydrogen is the raw material from which new stars can form within galaxies. Linking our radio measurements to optical studies and theoretical simulations will provide new tests of current galaxy evolution models.

The question of how the universe has evolved over cosmic time is one of the most fundamental in astronomy. We know that it has been moulded by gravity, written within Einstein’s general theory of relativity, but the complex physics of gas, stars and magnetic fields means that making predictions from our theories is not straightforward.

At SIfA, astronomers undertake detailed computer simulations of the growth and evolution of comic structure, following the collapse of gas and dark matter from the smooth universe after the Big Bang to the wealth of galaxies we see around us today. These simulations present a huge data-challenge and supercomputer techniques are needed to unpick the details and reveal the structure.

Australian astronomers are world leaders in the field of Galactic archaeology. The ages, chemistry and motions of stars across the Galaxy can be used to unravel how it first formed and evolved over billions of years. SIfA leads the GALAH spectroscopic survey to measure precise radial velocities and abundances of 30 elements for a million stars, and the Southern Stellar Stream Spectroscopic Survey (S5) that is mapping tidal streams within the Galactic Halo. A major SIfA strength is building dynamical models of the Galaxy through the use of both analytic functions, cosmological and N-body simulations.

The solar astrophysics group works in areas related to solar activity, which is dynamic behaviour in the Sun’s outer atmosphere (the solar corona) caused by the evolution of intense local magnetic fields. The most dramatic examples of solar activity are solar flares, which involve the explosive release of magnetic energy on time scales of minutes. Flares and related coronal mass ejections directly affect the Earth because they can produce dangerous local space weather conditions.

Recent work by the group includes modelling the magnetic field in the corona for active regions which produce large flares, to understand how the magnetic field changes during the flare, and devising a new measure of magnetic helicity – a quantity that represents the linkage of magnetic fields, and is approximately conserved in magnetic energy release.

Astroparticle physics is where the world of the microscopic, that of fundamental particles and fields, meets the large-scale universe. Our astronomers and physicists are exploring this complex interface by examining the impact of particle physics on the evolution of the universe, pushing the boundaries of our theoretical understanding of how dark matter interacts with normal atoms.

The physics of the “dark-sector” is being included in large-scale simulations of the growth and evolution of galaxies and structure in the universe, tracing how the interactions and decay of dark matter can inject energy into gas spread between the stars, revealing just what the next generation of ground and space telescopes will reveal about the dark universe.

Transients are astronomical objects that appear and disappear or change rapidly; they are our window to some of the most extreme processes in the Universe. Transient events can occur when black holes form, causing supernovae and gamma-ray bursts; when stars collide with black holes; or when hot, magnetised planets interact with their host stars.

There are also a multitude of mysterious transients of unknown origin, like fast radio bursts. Radio astronomy is undergoing a revolution in the discovery and study of transients. We lead projects on cutting-edge telescopes such as the Australian SKA Pathfinder (ASKAP) which allows us to see the dynamic radio sky in ways that were not previously possible.

SAIL is composed of 9 laboratories with researchers working on the development and modification of existing photonics technologies. A key element of astrophotonics is the integration of these technologies into high performance and precision instruments used for astronomy. SAIL research focuses on two main instrumentation techniques: spectroscopy and interferometry. A major research area is the development of unique optical fibres such as Fibre Bragg Grating and Hexabundle.

Another prominent aspect of photonics is devices that provide fine control of light and its different properties as astronomy requires the careful detection of photons in order to elaborate and validate complex astrophysical models. Examples are laser combs, scramblers and 3D lanterns. SAIL also has strong collaborations with other Australian universities and facilities.

The Astralis Instrumentation Consortium (Astralis) is a team of astronomy instrumentation experts across three nodes: Astralis -USyd is based within SIfA, Macquarie University (Astralis-AAO), and the Australian National University (Astralis-AITC) creating world-leading astronomical instrumentation to help survey and better understand our night skies.

Astralis-USyd are developing new in house technologies in optical fibres, photonics, interferometry and robotic positioning. The recently commissioned Hector instrument for the Anglo-Australian Telescope features our new optical fibre imaging bundles (Hexabundles) and a new robotic positioning system. Ongoing projects include the Heimdallr fringe-tracking and Advanced Photonic Nuller (APN) instruments for ESO’s Very Large Telescope (VLT) and collaborations with the SUBARU telescope in Hawaii.