Once the James Webb Space Telescope begins science operations this summer, it will the world’s most powerful space telescope, and it will open new avenues for astronomy research. One of the researchers who will be working with James Webb, Massimo Stiavelli, the Webb Mission Office head at the Space Telescope Science Institute, has shared more information about how Webb will look back in time at some of the earliest stars and galaxies.
Because light takes time to travel, the further away from Earth we look, the earlier we are seeing in the development of the universe. Webb will be able to see more distant galaxies than ever before, allowing researchers to get a glimpse of the early stages of the universe. By looking at the composition of these very early stars and galaxies, researchers can get an idea of what was happening in the few minutes after the Big Bang.
“The chemical composition of the early universe, just after the big bang, is the product of the nuclear processes that took place in the first few minutes of the universe’s existence,” Stiavelli said, as shared in a NASA blog post. “These processes are known as ‘primordial nucleosynthesis.’ One of the predictions of this model is that the chemical composition of the early universe is largely hydrogen and helium. There were only traces of heavier elements, which formed later in stars. These predictions are compatible with observations, and are in fact one of the key pieces of evidence that support the hot big bang model.”
Webb will be searching out examples of these very old stars to see if they support current theories about the Big Bang. “The earliest stars formed out of material with this primordial composition,” Stiavelli said. “Finding these stars, commonly dubbed as the ‘First Stars’ or ‘Population III stars,’ is an important verification of our cosmological model, and it is within reach of the James Webb Space Telescope. Webb might not be able to detect individual stars from the beginning of the universe, but it can detect some of the first galaxies containing these stars.”
Stiavelli’s project is to look at one of the furthest galaxies discovered to date, called MACS1149-JD1, using Webb. The team will measure how much of the galaxy is made up of heavier elements, using an instrument called a spectrograph, so they can confirm whether it is made up of these very early stars. The project will be a part of Webb’s first year of science operations.
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