Apparently, the first stars in the universe formed even earlier than we had initially thought. Researchers looking into the early universe found that there’s no sign of first-generation stars in the galaxies that existed 500 million to 1 billion years after The Big Bang happened.
According to the lead author of the study, Rachana Bhatawdekar, “These results have profound astrophysical consequences, as they show that galaxies must have formed much earlier than we thought.”
The author of the study, together with her colleagues, used the Hubble Space Telescope and Spitzer Space Telescope, together with European Southern Observatory’s Telescope in Chile, in order to find Population III stars in distant galaxies.
Why Population III stars are easier to identify?
Population III stars were actually the first suns to form in our 13.8 billion–year–old universe, and we can identify them thanks to their very unique composition: they’re made out of helium, hydrogen, and lithium, and these are the only elements which were around after The Big Bang.
The stars from the Milky Way Galaxy are classified into two groups: Population I stars, such as the sun of Earth and Population II stars, which are not that rich in heavy elements, as the Population I stars are.
Researchers took advantage of something called gravitational lensing. They used a huge galaxy cluster as a sort of magnifying glass, which allowed them to study small and distant galaxies, which are also very incredibly faint.
It has taken these background galaxies about 13.3 billion years to reach Earth, which means that these objects are basically time capsules full of information about the early universe. There is the answer to what types of stars were shining back then. However, according to Bhatawdekar, “We found no evidence of these first-generation Population III stars in this cosmic time interval.”