The First Star

After our universe popped into existence 13.7 billion years ago, there were no galaxies, no stars, not much of anything that we would recognize for at least a hundred million years and possibly longer. In fact, there was no light until the first photons appeared, but then a fog developed, a fog of hydrogen that made the universe opaque. Eventually, the fog dissipated because hydrogen atoms began to clump and then gravity took over to condense hydrogen down into a massive ball. This compression effect made the hydrogen gas heat up. This is a well-known thermodynamic law. This heating process caused the hydrogen gas to expand, and a balancing act between gravity and expansion prevented further compression, except for a little trick that the hydrogen atoms know, and that was to form hydrogen molecules. Hydrogen atoms formed hydrogen molecules and this process absorbed heat that allowed the hydrogen to further compress until it began to fuse into helium. At this instant, a star was born.

The trick for astronomers was to find the very first star. Unfortunately, this primordial star is no longer around, but it was possible to find stars that were perhaps second generation of this first star. What astronomers had to find is a star like ours that has almost no metal in its spectrum. The very first stars were huge blue stars that were extremely bright—hundreds of thousands of times brighter than our sun—and burned bright for only a million years or so before using up their hydrogen fuel and fusing higher elements until they formed iron. Iron caused the fusion reactions to cease, and this made the star explode in a supernova. In fact these supernovae were so powerful they were called mega-supernovae. These humongous explosions formed all of the higher elements, including the metals.

So, when astronomers find stars with very little metal in their spectra, it means that they are first generation stars, not second-generation stars like our sun, which is a metal-rich star that forms planets that can support life.

Astronomers did find stars that are first generation and related to the first star by finding low-metallic stars, and they used the data to create a computer simulation that would show what the first star was like and what it did to help form the rest of the stars that we see in the universe.

One of the things that they found is that the first stars were created in clumps of dark matter and gas where 100,000 solar masses of material clumped together. There were only a few of these clumps in the entire universe.

The very first star was a monster about 100 times the mass of our sun and it would have been blue with plenty of ultraviolet light. It only lasted a few million years before exploding in a supernova. Stars like this were composed entirely of hydrogen and helium. It wasn't until the formation of second-generation stars to where they looked like our sun with many different elements, including metals, in them.
If this star produced a massive gamma ray burst, it might be detectable with the new instruments that will be coming on line in the future.

Thanks for reading.