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Star Struck

Monash astrophysicists are calculating the chemical evolution of the universe from its birth to the present. COREY NASSAU reports

Although they may not have always been in the form of wine, says Dr John Lattanzio, the molecules that made up your last drop of pinot were once spewed forth from a supernova or red-giant star.

But while the deputy head of the School of Mathematical Sciences spends much of his time studying the evolution and internal structure of stars, you’d be hard pressed to find him gazing at the night sky. He is more likely to be found in a laboratory using powerful computers that run a single calculation for weeks.

For the past decade, Dr Lattanzio (below) and his team have been successfully showing how stars produce various elements, as well as the relative amounts of the elements they produce.

According to Dr Lattanzio, stars are naturally occurring nuclear (fusion) reactors that are born, evolve and eventually die. Learning about this process is playing an important part in understanding how our planet formed and how we came to be.

"The big bang made hydrogen and helium and that's about it," Dr Lattanzio says. "There were also tiny amounts of lithium, beryllium and boron, but nothing else. So the carbon in our bodies, the metal in a spectacle frame and the gold in a wedding band all had to come from somewhere else."

Mysteries such as these have fuelled the researcher's passion to discover how all the elements came to be and from which stars they originated.

"What we're trying to do is work out where everything came from – all these building blocks that were ready to form animals and people and every object in our daily lives," Dr Lattanzio says.

In order to model this, Dr Lattanzio and a team of researchers have been studying a common type of star, known as a red-giant, or more specifically the Asymptotic Giant Branch red-giant (AGB star).

"I started working on the evolution of AGB stars because they show some fascinating physics – but then it became apparent that they produce an enormous amount of chemical species, and I became much more interested in nuclear astrophysics," he says.

"Most stars go through the red-giant phase and they outnumber the better-known supernovae enormously. So although each red-giant doesn't make nearly as much material as a supernova, there are so many more of them in the galaxy that they make about half of the carbon in the universe, including that found in our own bodies."

Dr Lattanzio and his team are currently working in collaboration with overseas researchers in order to determine the amounts or ‘yields’ of the different elements produced by stars of all masses. Because Monash produces the best models of AGB stars in the world, the team is busy

providing the yields of these stars for the rest of the astronomical community.

While there are international researchers who are using stardust-grains recovered from inside meteorites to measure exact amounts of the materials produced by them, there is a fundamental place for the work going on in the School of Mathematical Sciences – a fact widely recognised by

Dr Lattanzio's peers.

"We explain their data. Measuring accurately may tell you how much of a substance is there, but it tells you nothing about how it got there, the formation process or its origin. That requires theory and modelling."

But theory and modelling don't always reveal a happy ending, according to Dr Lattanzio, whose calculations show a very different sun millions of years from now.

"The sun that currently provides the earth with heat and light will eventually evolve into a red-giant that will turn predator and swallow us whole," he predicts.

"Given the age of our solar system in relation to the age of the galaxy, this could well have happened before.

"It is very possible there was once another star like our sun, complete with planets and living beings. That star could have died and swallowed everything up before throwing it all back and forming what we have today. We could very easily be recycled aliens." 

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