The more evolved a galaxy is, the more collectively chaotic the orbits of its many stars are, new research shows, answering a key detail about how galaxies age.once every 225 million years, at a velocity averaging 514,495 mph . Astronomers call this a"galactic year." The sun's path around thehave a greater degree of randomness, with their orbits adopting a wide variety of velocities and angles relative to the plane of their galaxy.
"When we did the analysis, we found that age … is always the most important parameter," Scott Croom of the University of Sydney, who led the research, said in a."Once you account for age, there is essentially no environmental trend, and it's similar for mass. If you find a young galaxy, it will be rotating, whatever environment it is in, and if you find an old galaxy, it will have more random orbits, whether it's in a dense environment or a void.
In dense environments, gravitational interactions between nearby galaxies can also stir up a galaxy's gas and prompt it into a frenzy of star formation called a"starburst." Feedback in the form of radiation from hot, newly born stars in a starburst, or from jets coming from an activethat has switched on thanks to a large amount of matter funneled toward its maw by the interactions, can heat the gas in a galaxy and blow it into intergalactic space, preventing it from forming stars.