by Bärbel Koribalski (CASS)

The Circinus galaxy was discovered relatively recently as it hides behind the bright stellar disk of the Milky Way. The color composite image shows the cold neutral hydrogen gas in blue , warm dust in red , and stars in green . It highlights the disk and inner spiral arms of the Circinus Galaxy; its hydrogen envelope extends well beyond the image shown here. The Spitzer Space Telescope was used to map Circinus in the infrared at wavelength of 3.6 and 8 micron, while the 21-cm spectral line of hydrogen (HI) was mapped with the Australia Telescope Compact Array in Narrabri (published by For, Koribalski & Jarrett 2012 ). Hydrogen is the fuel for star formation and a tracer for dark matter in galaxies. – My one minute lightning talk at Sydney’s Vivid Festival featured this image, was recounted in the (no longer existing) CSIRO Universe Blog.