Galaxy CR7 isn’t only unusual for its distance or brightness – it could contain the Population III stars that shaped our universe.
Here’s a fun fact about space: When you look at distant objects, you’re seeing them as they existed in the distant past. That means faraway stars and galaxies can actually tell us quite a bit about the origins of our universe. But is it possible to find the first stars that ever were? Well, according to astronomers we may have finally found them – in a distant galaxy called CR7 which meets all the criteria for stars that shaped the entire cosmos.
Galaxy CR7 – short for Cosmos Redshift 7 – is an unusually bright galaxy about 13.02 billion lights years away from Earth. But what’s even stranger is that CR7 contains strong ionized helium emission and no sign of heavier elements. In short, that means CR7’s stars are probably Population III stars, the first generation that formed 800 million years after the Big Bang.
Population III stars are significant because they created the building blocks of matter we’re familiar with today. Without them, gases like hydrogen, helium, and lithium would never have transformed into elements like oxygen and carbon – essential materials for life as we know it. And that’s not even getting into metallic elements, iron, nitrogen, and pretty much everything you learned about in your high school science courses.
“The discovery challenged our expectations from the start, as we didn’t expect to find such a bright galaxy,” David Sobral of the Institute of Astrophysics and Space Sciences in Portugal explained. “Then, by unveiling the nature of CR7 piece by piece, we understood that not only had we found by far the most luminous distant galaxy, but also started to realize that it had every single characteristic expected of Population III stars. Those stars were the ones that formed the first heavy atoms that ultimately allowed us to be here.
“It doesn’t really get any more exciting than this.”
Sadly, we’re never going to actually be able to visit CR7’s stars for ourselves, unless a mad man with a blue box took us there. Population III stars only lasted for about two million years before burning out, which is a big reason why they’re so hard to find now. That makes CR7 a wonderfully rare find, and why astronomers will study it very closely in the months and years ahead.