Not much is known about the early stars of the Universe, probably because astronomers have never seen evidence of them. However, now, a team of scientists have discovered a star that contains traces of a star believed to be one of the first stars of the Universe.
These early stars were huge, with masses hundreds of times larger than that of our Sun. Their lives, however, were short, so none exist today. This discovery could give us valuable new insight on the formation of the Universe.
The Universe's early stars were unlike today's stars, which are a lot like our Sun and are full of heavy elements, such as carbon, oxygen and iron. Older stars have very few of these elements. Some of the earliest stars, which formed about 100 to 250 million years ago contained no heavy elements at all and were probably just hydrogen and helium. However, when these stars went supernova, the hydrogen and helium fused and created heavier elements, forming new stars, more like what we're familiar with today.
These early stars were also huge, which meant that they had a lifespan of just a few million years. Scientists believe most of these stars were gone by 800 million years after the Big Bang.
A team of Japanese and American scientists found evidence of one such star by using something they call "stellar archaeology." Because there aren't any remains left of the stars' supernovae, they looked at newer stars that could have absorbed traces of the earlier stars.
Using the Subaru Telescope in Hawaii, researchers observed stars that had low masses, at least in comparison to modern stars. Believing that these stars are second-generation, they studied these stars' chemical compositions.
After studying a second-generation star that is about 1,000 light years from Earth, the researchers found that it had a chemical composition that matched what they thought might occur if the second-generation star formed from material created after the explosion of a larger first-generation star.
This discovery could tell us a lot about how modern stars formed, as well as how the galaxy came together.
"The impact of very-massive stars and their explosions on subsequent star formation and galaxy formation should be significant," says Wako Aoki, of the National Astronomical Observatory of Japan.
Although no first-generation stars should exist, astronomers think maybe smaller ones are out there, waiting for discovery.
"This is one of the main targets for [NASA's] James Webb Space Telescope (JWST), planned for launch in 2018," says Voker Bromm, University of Texas Austin.
