Giant stars reveal inner secrets for the first time

11 April 2011

University of Sydney astrophysicists are behind a major breakthrough in the study of stars known as red giants, finding a way to peer deep into their cores to discover which ones are in early infancy, which are fresh-faced teenagers, and which are facing their dying days.


Giant star evolution
Giant star evolution

The paper's lead author, Professor Tim Bedding who is based in the School of Physics, explains that "red giants are evolved stars that have exhausted the supply of hydrogen in their cores that powers nuclear fusion, and instead burn hydrogen in a surrounding shell. Towards the end of their lives, red giants begin burning the helium in their cores."

The Kepler space telescope has allowed Professor Bedding and colleagues to continuously study star light from hundreds of red giants at an unprecedented level of precision for nearly a year, giving a window into the stars' cores.


"Under the right conditions these waves interact with other waves trapped inside the star's helium core. It is these 'mixed' oscillation modes that are the key to understanding a star's particular life stage. By carefully measuring very subtle features of the oscillations in a star's brightness we can see that some stars have run out of hydrogen in the centre and are now burning helium, and therefore at a later stage of life."


Professor Bedding and his colleagues work in an emerging field called asteroseismology. "In the same way that geologists use earthquakes to explore Earth's interior, we use star quakes to explore the internal structure of stars," he explained.



Contact: Professor Tim Bedding

Phone: 02 9351 2680, 0425 310 476

Email: 07010c1c2b34025f2075345f4b412b4c206801263e314a1017375f041d