New technique to “revolutionise” astronomy

Credit: iStockphoto

SYDNEY: There is a frustrating amount of light pollution in the night sky. But a new invention could “revolutionise” the way astronomers see the stars, said an Australian-German collaboration last night.

“Once up and running it will exceed the power of the James Webb telescope [which will be the successor to Hubble],” said project leader, astronomer Joss Bland-Hawthorn from the University of Sydney in Australia.

Space telescopes are able to view the stars without the interference of the Earth’s atmosphere. On Earth, however, interference from the atmosphere can hinder astronomical ‘seeing’.

80% efficiency

In particular, hydroxyl molecules in the Earth’s atmosphere scatter infrared light, making the sky ‘bright’ in this part of the spectrum, and hindering infrared telescopes which are useful for seeing distant stars or objects obscured by dust.

“What we are doing now is developing an instrument [called a] photon integrating multi-mode spectrograph,” said Bland-Hawthorn. “Good light goes forward, and bad light goes back.”

The instrument, about the size of a microwave oven, consists of stacked layers of fibre optics that channel single photons. This enables the astronomers to focus on photons from particular objects – such as stars – and ignore the unwanted light from the rest of the sky.

“We are now suppressing the entire night sky with a level of 80% efficiency and this will completely revolutionise the way that astronomy is done,” said Bland-Hawthorn.

Image enhancement

Bland-Hawthorn announced the development at an event marking a new international collaboration in astrophotonics, which applies light-collecting technology such as fibre optics to astronomy.

First generation prototypes of the spectrograph have been built and several hundred are expected to be made next year and implemented in Australian and international telescopes, initially on the 3.9-metre Anglo-Australian Telescope at Coonabarabran, NSW.

Fibre optics catch and transmit light, which makes them ideal for enhancing telescopic images of space. “Fibres act to suppress the persistent infrared light from the night sky,” said Bland-Hawthorn.

“In the infrared, daylight is the same as night, the sky radiates in the infrared due to the presence of hydroxyl molecules in the atmosphere. We can remove the bright lines from the hydroxyl molecules: if you remove these, the sky goes pitch black,” he said.

The result will enable astronomers to get better observations of the distant universe, including the first stars and galaxies, he said. “We’ve never been able to do this from Earth. It breaks a barrier in instrumentation development in over 100 years.”

Astronomer Anne Green, director of the University of Sydney’s Molonglo Observatory Synthesis Telescope said she was expecting “amazing outcomes and significant science” from the collaboration, between the Consortium for Australian Astrophotonics and University of Potsdam in Germany.

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