Thirteen billion years old ultra-blue galaxies, which were formed around 700 million years after the Big Bang, have been discovered by astronomers, US space agency NASA has said.
Using NASA's Hubble Space Telescope, astronomers from University of California have broken the distance limit for galaxies by uncovering the primordial population of compact and ultra-blue galaxies that were never seen before.
These newly-found galaxies are crucial to understand the link between the birth of the first stars, the formation of the first galaxies and the sequence of evolutionary events that resulted in the assembly of Milky Way and other "mature" elliptical and majestic spiral galaxies in today's universe.
The Hubble Ultra Deep Field 2009 (HUDF09) team combined the new Hubble data with observations from NASA's Spitzer Space Telescope to estimate the ages and masses of these primordial galaxies.
"The masses are just 1 per cent of those of the Milky Way," explained team member Ivo Labbe of the Carnegie Observatories.
He further noted that "to our surprise, the results show that these galaxies existed at 700 million years after the Big Bang and must have started forming stars hundreds of millions of years earlier, pushing back the time of the earliest star formation in the universe."