Using "Mopra" radio telescope, an international team, spotted a massive cloud of mostly hydrogen gas and dust, three or more light-years across, that is collapsing in on itself and will probably form a huge cluster of stars.

Dr Stuart Ryder of the Anglo-Australian Observatory said the discovery was made during a survey of more than 200 gas clouds. "With clouds like this we can test theories of massive star cluster formation in great detail," he said.

The gas cloud, called BYF73, is about 8,000 light years away, in the constellation of Carina (the keel) in the Southern sky.

Evidence for "infalling" gas came from the radio telescope's detection of two kinds of molecules in the cloud - HCO+ and H13CO+. The spectral lines from the HCO+ molecules in particular showed the gas had a velocity and temperature pattern that indicated collapse.

The CSIRO telescope observations were confirmed by observations with Atacama Submillimeter Telescope Experiment (ATSE) telescope in Chile.

The team has calculated that the gas is falling in at the rate of about three per cent of the Sun's mass every year -- one of the highest rates known.

Follow-up infrared observations made with the 3.9-m Anglo-Australian Telescope showed signs of massive young stars that have already formed right at the centre of the gas clump, and new stars forming.

Gas cloud BYF73 was found during a large-scale search for massive star-forming regions -- the Census of High and Medium-mass Protostars, or CHaMP. This is one of the largest, most uniform and least biased surveys to date of massive star-forming regions in our Galaxy.

The findings have been published in the 'Monthly Notices of the Royal Astronomical Society' journal.