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Astrophysicists have long scratched their head when it came to figuring out how galaxies like ours get and maintain their characteristic arms, and now a new study has answered this age old questions.

A team of researchers from the University of Wisconsin-Madison and the Harvard-Smithsonian Center for Astrophysics reports simulations that seem to resolve long-standing questions about the origin and life history of spiral arms in disk galaxies. The study was published in the March 20th issue of The Astrophysical Journal.

Scientists say that by using powerful new computer simulations, they can for the first time show that stellar spiral arms are not transient features, as it was commonly thought, but rather are "self-perpetuating, persistent and surprisingly long-lived."

"We show for the first time that stellar spiral arms are not transient features, as claimed for several decades," says UW-Madison astrophysicist Elena D'Onghia, who led the new research along with Harvard colleagues Mark Vogelsberger and Lars Hernquist.

"The spiral arms are self-perpetuating, persistent, and surprisingly long lived," adds Vogelsberger.

According to co-authors Vogelsberger and Lars Hernquist from the Harvard-Smithsonian Center for Astrophysics, the new computer simulations can be used to reinterpret observational data by looking at high-density molecular clouds and gravitationally induced "holes" in space as the mechanisms driving the formation of the emblematic arms of spiral galaxies.

"We find they are forming spiral arms," explains D'Onghia. "Past theory held the arms would go away with the perturbations removed, but we see that (once formed) 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 (the influence of) gravity, even in the extreme when the perturbations are no longer there."