ANU plays starring role in heavenly clean-up
The giant Magellan Telescope.
Australian National University researchers have found a way to take the twinkle out of stars – welcome news for the international astronomers who will work on the world’s biggest light telescope being built in Chile.
Stars appear to twinkle because of the disruption caused by turbulence in the atmosphere, which distorts the light. This can make stars and galaxies appear little more than a speckly mess for astronomers.
‘‘Instead of a nice circular image, you get a speckly mess,’’ ANU physicist Francis Bennet said. ‘‘And instead of clean pin-points you’ll have messy blobs for galaxies.’’
In collaboration with colleagues at Mount Stromlo Observatory, Dr Bennet has developed an ‘‘adaptive optic system’’ which will counter the effect of atmospheric turbulence on the wavefront, which makes the image of the stars.
The device, which has just emerged from its preliminary design phase, will become a key part of the Giant Magellan Telescope. The telescope, the largest optical telescope ever to be built, is due for completion in 2020.
Inside the telescope will be seven 8.4 metre diameter mirrors and a smaller secondary mirror – also with seven segments – placed at the apex of the telescope. The Australian designed adaptive optic system will operate near the second mirror, where it will correct the distortions caused by atmospheric turbulence by essentially telling the smaller mirrors how to bend to counteract the ‘‘twinkle’’ of the stars.
This will deliver a clearer image – much sharper than those produced by the Hubble Space Telescope.
‘‘Hubble has a relatively smaller mirror,’’ Dr Bennet said. ‘‘It’s only a metre or two whereas this one will be some 25 metres so you can image things in fine detail. But you need an adaptive optic system to provide the correction.’’
Currently astronomers can see about 11 billion light years into the past. But a telescope like the Giant Magellan Telescope, which is able to see much fainter objects, will allow us to see as far as 13 billion light years back in time.
Dr Bennet will outline the optic system on Wednesday at the Australian Institute of Physics congress in Sydney.
Based at the Las Campanas Observatory in the Atacama Desert, the site for the Giant Magellan Telescope was selected because it is free from atmospheric pollution and largely free from light pollution.