Galaxies change shape as they age, study reports

Researchers have discovered that a galaxy's shape may reveal its age.
By Joseph Scalise | Apr 26, 2018
A galaxy's shape may show how old it is, according to a new study published in the journalNature Astronomy.

Galaxies come in many forms, ranging from spiral pinwheels to flat pancakes to round balls. Though scientists are not sure why so many different shapes exist, this new study gives insight into the strange mechanisms.

To take a deeper look into the shapes, a group of scientists from the University of Sydney analyzed data taken from the Anglo-Australian Telescope at Siding Spring Observatory in Australia. That then allowed them to compile evidence on each and every configuration.

"Over the last couple of years, we have gathered 3D measurements of over a thousand galaxies of all kinds and with a hundred-fold range in mass," explained lead author Jesse van de Sande, an astrophysicist at the University of Sydney, according toPopular Science.

Though it is not possible to directly measure a galaxy's 3D shape, astronomers can infer it by looking at the motions of the stars within it.

Almost all galaxies appear as "squashed spheres." However, the new research shows that the younger a galaxy's stars are the more squashed it is. As a result, newer galaxies tend to appear as flat, thin disks while older ones are puffier. In addition, astronomers can infer age by looking at the color of stars within a system as well.

This research is the first time scientists have found a concrete link between a galaxy's shape and its age. The connection is so strong that it holds up for every known system, including pinwheel galaxies that both have a flat disk and puffy center.

As a result, the new findings give insight into galaxy formation and could help scientists better understand the larger mechanisms of the universe. There are many questions that still need to be answered -- including if galaxies are born flat and then become round, or if some are naturally puffy -- and the team hopes more research will shed light on such conundrums.

"To see those relationships, you need detailed information on large numbers of galaxies," said study co-author Julia Bryant, a researcher at the University of Sydney, according to Space Daily.

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