Like bubbles bursting on the surface of a glass of champagne, ‘bubbles’ in our Galaxy burst and leave flecks of material in the form of clouds of hydrogen gas, researchers using CSIRO’s Parkes telescope have found.Their study explains the origin of these clouds for the first time.

Swinburne University PhD student Alyson Ford (now at the University of Michigan) and her supervisors; Dr Naomi McClure-Griffiths (CSIRO Astronomy and Space Science) and Felix Lockman (US National Radio Astronomy Observatory), have made the first detailed observations of ‘halo’ gas clouds in our Galaxy.

Just as Earth has an atmosphere, the main starry disk of our Galaxy is surrounded by a thinner halo of stars, gas and ‘dark matter’.

The halo clouds skim the surface of our Galaxy, sitting 400 to 10 000 light-years outside the Galactic disk. They are big: an average-sized cloud contains hydrogen gas 700 times the mass of the Sun and is about 200 light-years across.

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