Unique Galaxy Shows a Stellar 'Circle of Life'

NASA's Spitzer Space Telescope (SST) has recently unveiled new images of an uniquely shaped galaxy that looks a lot like a spoked wheel. What makes this galaxy particularly unique is the fact that it is quite old, and yet is characterized by a ring of freshly born stars.

"The rest of the galaxy is done maturing," Kartik Sheth of the National Radio Astronomy Observatory said in a recent statement. "But the outer ring is just now starting to light up with stars."

That's pretty unusual among galaxies, which are traditionally either old and well developed, or young and full of clouds of precursor star material commonly referred to as "star nurseries."

However, the galaxy of NGC 1291 seems to be an old woman who doesn't understand that her days of being a mother are over. And somehow, the galaxy is miraculously still producing stars on its outermost edge. The light of these new births was easily picked up in infrared imagery by the SST.

Even without its unique qualities, NGC 1291 is no normal galaxy. The old stars at its center streak across like a single long bar holding it open. This identifies it as what astronomers simply call a "barred galaxy."

And during their early days, barred galaxies are prime star makers. As the galaxy's bar orbits its center, it churns material around, forcing stars and gas from their original circular orbits into large, non-circular, radial orbits. This creates resonances - areas where gas is compressed and triggered to form new stars. The Milky Way galaxy has a bar, though not as prominent as the one in NGC 1291, according to NASA.

"Now, with Spitzer we can measure the precise shape and distribution of matter within the bar structures," said Sheth. "The bars are a natural product of cosmic evolution, and they are part of the galaxies' endoskeleton. Examining this endoskeleton for the fossilized clues to their past gives us a unique view of their evolution."

In the case of NGC 1291, the astronomers suspect that it just has a great deal of producer star material to "churn," taking longer than most galaxies to finish up its star production cycle. The result is an old galaxy with a ring of young stars.