Spiral galaxies are beautiful astronomical realities that have long been the cause of speculation, with no definitive conclusion having been made over what causes them. Researchers from the Harvard-Smithsonian Center for Astrophysics and the University of Wisconsin-Madison have helped solve this conundrum, stating that they've proved the spiral arms are persistent, long-lived, and self-perpetuating.
The majority of galaxies are not spiral-shaped, but those that are, including our own Milky Way, have been a source of mystery. Scientists have long-speculated that the so-called spiral arms of these galaxies could be a somewhat stable existence, or they could be transient in nature. Using computer simulations, the team responsible for the discovery monitored the motions of stellar particles, which showed that the arms are, in fact, fairly long-lived and stable.
According to a University of Wisconsin-Madison Professor named D'Onghia who was part of the team, "Past theory held the arms would go away with the perturbations removed, but we see that [after formation] the arms self-perpetuate, even when the perturbations are removed. It proves that once the arms are generated through these clouds, they can exist on their own through gravity, even in the extreme when the perturbations are no longer there."
As it turns out, spiral galaxies are not solely produced by the gravitational pull of other nearby galaxies, but instead are initiated by giant molecular clouds. These molecular clouds, in combination with holes formed by gravitational forces, kick off the formation of spiral galaxies. Using these simulations and others, researchers can continue to study the formation of galaxies, perhaps even one day discovering how the Milky Way came to be.
[via Science Recorder]