Colliding galaxies have been observed forming a super-galaxy that is giving birth to stars at an astonishing rate. The two ancient star systems will one day form an elliptical galaxy 10 times the size of our own Milky Way.
The two galaxies are located 11 billion light years away from the Earth. The Universe is measured to be about 14 billion years old, which means that this galaxy formation we are seeing now occurred with the Universe was only three billion years old.
At this time in the history of the Cosmos, galaxies were largely filled with dead stars that had long ago exhausted their nuclear fuel. The galaxies spotted here, however, are seen actively forming new stars within their stellar nurseries. The images were complied from images taken by four different telescopes.
Hai Fu, lead author study from the University of California-Irvine initially believed that he was viewing a single galaxy called HXMM01, but this turned out not to be the case. What appeared to be a single object was, instead, two galaxies located 62,000 light years from one another, on a collision course with one another.The two galaxies will eventually merge into one giant elliptical galaxy. Carefully measuring the effects of this galactic merger should help astronomers better understand the role that such collisions played in the evolution of the early Universe.
Fu said, "We're looking at a younger phase in the life of these galaxies –– an adolescent burst of activity that won't last very long."
The discovery that the Universe went through a period of "red and dead" galaxies between 9 and 11 billion years ago is itself a fairly recent discovery. Astronomers only realized this was the case around a decade ago. The early stars burned out quickly and most galaxies were not forming new stars.
This newly-discovered formation, however, is seen giving birth to an estimated 2,000 stars each year. That rate of star formation is nearly 1,000 times faster than what we observe in our own galaxy.
"Finding this type of galaxy is as important as the discovery of the archeopteryx was in understanding dinosaurs' evolution into birds," explained Fu, "because they were both caught at a critical transitional phase."
The results of the study were published May 22 in the journal Nature.
