A galaxy as you’ve never seen it

New imaging hints at a violent past and a fatal future for the Small Magellanic cloud. Andrew Masterson reports.

The new radio image of the Small Magellanic Cloud.
The new radio image of the Small Magellanic Cloud.

It may be small but, boy, does it look hot.

Astronomers at the Australian National University in Canberra have compiled the most detailed radio image ever of the Small Magellanic Cloud, a dwarf galaxy about 200,000 light years from Earth outside the Milky Way.

The image was created using the Australian Square Kilometre Array (ASKAP), a powerful new radio telescope built and operated by the country’s premier research organisation, the CSIRO.

The results reveal a level of detail previously unseen, which allow astronomers to glean more accurate information about the galaxy’s past, and make better predictions about its future.

Co-lead researcher Naomi McClure-Griffiths says the image revealed a larger than expected accumulation of gas around the edges, indicating that the Small Magellanic Cloud had endured close encounters with its older “sibling”, the Large Magellanic Cloud, and the Milky Way.

These interactions, together with star explosions, had caused gas to be pushed out of the galaxy, twisting its form.

“The outlook for this dwarf galaxy is not good, as it’s likely to eventually be gobbled up by our Milky Way,” says McClure-Griffiths.

“Together, the Magellanic Clouds are characterised by their distorted structures, a bridge of material that connects them, and an enormous stream of hydrogen gas that trails behind their orbit – a bit like a comet.”

The ASKAP image is the first to build a picture of the galaxy based on the hydrogen gas that suffuses it. McClure-Griffiths says the result shows the structure in more depth and detail than previous infrared satellite images that depict only stars and dust.

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Andrew Masterson is news editor of Cosmos.
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