14 DAY TRIAL // So far, there were two known types of galaxies (excluding the peculiar ones that form by accident): the blue spiral ones, like our own, and red elliptical ones, shaped like a football. Their color (although the shades and contrast may differ) is very important, since it gives a hint on the age of the stars in the galaxy. Normally, young stars have a bluish hue, while the older ones are mostly red. The elliptical old galaxies are settled, calm versions of the younger spiraled ones.
But a new class of galaxies has recently been discovered, which may stand as a missing link between the two. It looks like a massive red spiral, combining the color of the elderly with the shape of the young. Researchers involved in the Space Telescope A901/902 Galaxy Evolution Survey and the Galaxy Zoo project believe this could be the teenage phase of a galaxy's life, before reaching the red, elliptical calmness of its adulthood.
"In order to have spiral arms, they must have been normal, blue, spiral galaxies up until fairly recently," explained Steven Bamford, a postdoctoral researcher at the University of Nottingham in England, in a press release, as cited by Wired. "But for some reason their star formation has been stopped, and they have turned red. Whatever caused them to stop forming stars can't have been particularly violent, or it would have destroyed the delicate spiral pattern."
The factors taken into account by the specialists during a galaxy's transition phases are its mass (which is very large in the case of the red spirals), its environment (galaxy-rich, but with an influence not yet completely comprehended) and possibly a violent phenomenon, like the clash between two galaxies.
"Just as a heavyweight fighter can withstand a blow that would bring a normal person to his knees, a big galaxy is more resistant to being messed around by its local environment," shared Bob Nichol from the University of Portsmouth, one of the scientists involved in the Galaxy Zoo project. "Therefore, the red spirals that we see tend to be the larger galaxies - presumably because the smaller ones are transformed more quickly."