KEY POINTS

  • ESA researchers used the Hubble Space Telescope to study a galaxy cluster
  • Hubble did not find traces of Population III in the galaxies hiding behind the cluster
  • Researchers believe Population III stars formed during a period that's too early for Hubble to detect

Using the Hubble Space Telescope, a team of astronomers was able to make an important discovery regarding the formation of the first generation of stars and galaxies in the universe. According to the astronomers, these cosmic objects may have formed much earlier than previously thought.

The discovery was made by researchers from the European Space Agency (ESA). They focused on studying the formation of the universe about 500 to one billion years after the Big Bang.

For their observations, the astronomers gazed at a galaxy cluster known as MACSJ0416. Through Hubble’s imaging capabilities, the researchers were able to remove the light from the foreground of the cluster.

Doing so enabled them to spot other galaxies in the background. As noted by the researchers, these galaxies have the lowest masses ever discovered through Hubble.

Based on the distance of the background galaxies, the researchers estimated that they could be from the time that the universe was less than a billion years old. As they viewed the background galaxies, they did not find evidence of the universe’s first generation of stars that are known as Population III.

“Forged from the primordial material that emerged from the Big Bang, [Population III] stars must have been made solely out of hydrogen, helium and lithium, the only elements that existed before processes in the cores of these stars could create heavier elements, such as oxygen, nitrogen, carbon and iron,” the ESA explained.

According to the researchers, this finding indicates that the galaxies behind the cluster may have formed earlier than previously thought. They also noted that the Population III stars might have formed during a period that’s too early to be probed by Hubble.

The researchers are hoping that Hubble’s successor, the James Webb Space Telescope, will have the necessary instruments to peek into the early stages of the universe.

“These results have profound astrophysical consequences as they show that galaxies must have formed much earlier than we thought,” Rachana Bhatawdekar, an ESA research fellow, said in a statement. “This also strongly supports the idea that low-mass/faint galaxies in the early Universe are responsible for reionization.”

MACSJ0416
Hubble's views of the galaxy cluster MACSJ0416 NASA, ESA, and M. Montes (University of New South Wales, Sydney, Australia)