Giant galaxy formation is similar to the birth of a snowflake

The giant elliptical galaxy NGC 1407. Image: Professor Duncan Forbes/ Subaru Telescope

From little things very big things will grow.

Professor Duncan Forbes from the Swinburne University of Technology has suggested that giant galaxies, which may contain billion of stars, form the same way as snowflakes. Like snowflakes, Professor Forbes says galaxies “need a little seed to get started.”

Using data from the 8.2 metre Subaru telescope and the 10 metre Keck telescope, both located in Hawaii, as well as the Hubble Space Telescope, Professor Forbes analysed the giant elliptical galaxy NGC 1407, 25 to 30 million light years away. “By astronomical standards, we would actually call that a nearby galaxy.”

Snowflakes and galaxies both appear to form in two phases. Snowflakes will start out by forming around a seed, such as a pollen grain or dust particle. For galaxies, this seed consist of an inner region of stars, formed from collapsing gas.

The snowflakes then begin to grow as water vapour then begins to accumulate on the surface of the snowflake. The galaxy collects more stars as part of it’s growth process.

The stars come from other smaller galaxies as they spiral towards the larger one. According to Professor Forbes, ‘it’s basically just gravity at work.”

The smaller galaxies are then ripped apart, with individual stars and star clusters deposited into the halo of the larger galaxy. “The galaxy we looked at has several thousand of these star clusters.”

It’s harder to see this process at work with our own galaxy- even though it’s closer, it only has 150 of these star clusters. But Professor Forbes says its good confirmation that a similar process to the one building the elliptical galaxies is also building spiral galaxies.

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