Translated and adapted by Mateus Lynniker from ScienceAlert
Back when the Universe was still just a little baby universe, there wasn’t much going on chemically. There was hydrogen, with a little bit of helium and a few traces of other stuff. The heavier elements didn’t arrive until stars formed, lived, and died.
Imagine, then, the scientists’ consternation when, using the James Webb Space Telescope to peer into the distant reaches of the Universe, they discovered significant amounts of carbon dust less than a billion years after the Big Bang.
The discovery suggests that there was some way to increase carbon production in the tumultuous early Universe – likely due to the death of massive stars, spewing it out into space as they died.
“Our detection of carbonaceous dust at redshift 4-7 provides crucial constraints on models and scenarios of dust production in the early Universe,” writes a team led by cosmologist Joris Witstok of the University of Cambridge in the UK.
The first billion years of the Universe’s life, known as the Cosmic Dawn, after the Big Bang 13.8 billion years ago, was a critical period. The first atoms formed; the first stars; the first light bloomed in the darkness. But it took stars themselves to forge significant amounts of elements heavier than hydrogen and helium.
In the hot, dense nuclear furnaces of their cores, stars collide atoms, fusing them into heavier elements in a process called stellar nucleosynthesis. But those heavier elements just pile up in the star until it runs out of fusion material and dies, spewing its contents into the space around it. It is a process that usually takes some time.
Witstok and his colleagues used JWST to study the dust during the Cosmic Dawn and spotted something strange. They found an unexpectedly strong feature in the spectrum associated with the absorption of light from carbon-rich dust in galaxies as early as 800 million years after the Big Bang.
The problem is that these dust grains are believed to take a few hundred million years to form, and the characteristics of the galaxies suggest that they are too young for this time scale of formation. But it is not an impossible problem to solve.
The Crab Nebula (NASA, ESA and Allison Loll/Jeff Hester/Arizona State University, Davide De Martin/ESA/Hubble)
It was believed that the first stars in the Universe were much more massive than the youngest stars we see around us today. As more massive stars burn through their fuel reserves more quickly, they would have lived relatively short lives, exploding in supernovae that could have shed heavier material relatively early.
There are also stars that exist today that are absolute dust factories. They are called Wolf-Rayet stars, massive stars that have reached the end of their lives, on the verge of going supernova. They don’t have a lot of hydrogen left, but they do have a lot of nitrogen or carbon, and they’re in the process of ejecting mass at a very high rate. This ejecta material is also rich in carbon.
The discovery of large amounts of carbon in multiple galaxies during the cosmic dawn could be evidence that these processes were not just occurring, but were more common during the early Universe than in more recent spacetime.
This in turn suggests that huge stars were the norm for the first generation, helping to explain why we don’t see any of them still circling the Universe today.
2023-07-20 01:42:15
#James #Webb #Telescope #Detected #Carbon
