In 1609 Galileo turned his telescope skyward to our closest neighbor, the moon, and vastly expanded the range of human vision. Now Alexander Kashlinsky of the Goddard Space Flight Center may have peered all the way to the most remote objects in the universe: the primordial stars that first lit up a pitch-black cosmos 200 million years after the Big Bang.
Detailed computer models imply that these so-called Population III stars formed from knots of dense gas and rapidly grew to more than 100 times the mass of our sun. They blazed brilliantly, but within just a few million years they burned out and exploded, spewing heavy elements that helped seed the formation of succeeding generations of stars and planets. Many astronomers have sought to confirm the existence of the first stars, but their searches have been inconclusive.
Kashlinsky and his team at Goddard examined a deep-exposure image of a patch of sky taken by NASA's orbiting Spitzer Space Telescope and then subtracted the light from all the evident stars and galaxies. What was left was a dim background glow never seen before. Kashlinsky cautions that he has still not observed individual members of Population III, but his group has ruled out every other type of object. "We see a signal that cannot be explained by stellar populations that we know," Kashlinsky says. "It suggests that there was a short era, maybe several hundred million years long, that was populated by huge stars unlike any that we see today."