"Unraveling the Chaos: Understanding the Messiness of Aging Galaxies"
New research shows that the more evolved a galaxy is, the more collectively chaotic the orbits of its stars become, with the real cause being the age of the galaxy rather than its mass or environment. Galaxies with ongoing star formation are considered "young" and have more ordered motions, while those where star formation has ceased are "old" and exhibit more random orbits. The random motions in older galaxies are attributed to a combination of stars born with more energy and feedback that quickly quenches further star formation. These findings are based on observations of 3,000 galaxies by the SAMI Galaxy Survey and were published in the Monthly Notices of the Royal Astronomical Society.