A burst of stars 13 billion years ago
(Phys.org) —The universe immediately following the big bang contained mostly hydrogen and some helium. All the other elements needed to make galaxies, planets, and life were formed in stellar interiors or related processes. It is no wonder, then, that the epoch of star formation in the early universe, and the processes at work, are key cosmological questions. Astronomers think that stars started forming in earnest only a few hundred million years after the big bang, but the great bursts of star formation needed to shape the current universe have so far been detected occurring a few billion years later, in galaxies lit up at infrared wavelengths as their dust absorbs light from massive young stars. It has been proposed that similar bursts of activity might actually have happened at earlier times but just gone undetected. They are unnoticed no longer.