NASA’s James Webb Space Telescope has taken images of actively forming stars like this pair, known as Herbig Halo 46/47, as well as observed stars near the dawn of the universe.
STScI Copyright: NASA, ESA, CSA/STScI
With the James Webb Space Telescope (JWST), we’re ecstatically close to seeing the beginning of the dawn of the universe: the moment the first stars and galaxies formed.
“We’ve probably made more progress in the last 12 months than in the last 20 years, because it’s a very powerful telescope,” says the astrophysicist. Richard Ellis At University College London.
Ellis spoke to the crowd At New Scientist Live at London’s ExCeL Center on 7 October, we will discuss the latest discoveries from JWST, which has been running since 2022 and is still producing new science at an incredible rate. “This is something we couldn’t have done six months ago,” he says. new scientist.
Some of the most striking results come from observations of the most distant galaxies we can see, which date back to just a few hundred million years after the universe began. These galaxies appear to be fewer in number and brighter than the standard model of cosmology, also known as the lambda cold dark matter model, suggests.
“They systematically become three to five times brighter, which may not sound like much, but in hindsight; “When the universe is older, these theoretical models match the data very well,” says Ellis. Using JWST to look beyond what the Hubble Space Telescope can see, to the earliest galaxies just 400 million years after the Big Bang, seems to show something different, he says.
As for why this is happening, it’s possible that early stars were systematically more massive than the stars we see today, and therefore emitted more light, and that early galaxies were There are several explanations, including that it is forming stars quickly.
If either scenario, or combination of them, is true, the standard model of cosmology would need some tweaking, but it would still be fundamentally correct, Ellis said. “We’re not in a cosmological crisis. We’re not at the point where we’re abandoning the cold dark matter view or abandoning the big bang.”
Richard Ellis spoke at New Scientist Live on October 7th
Richard Ellis
The chemical composition of these galaxies also suggests that we are getting closer to observing celestial bodies from the beginning of the dawn of the universe. The first stars should have been composed almost entirely of hydrogen and helium. It is only later in life that they produce heavier elements.
Looking at the earliest stars we’ve ever seen, “we can calculate the abundance of oxygen, carbon, and nitrogen compared to the Sun, which is now down to 1 to 4 percent at this early point in time.” ,” says Ellis. “It is clear that in the most distant galaxies we see, the universe is moving towards a primordial state.”
Early stars can be born and die in as little as 5 million years, and trying to observe them in their entirety is extremely difficult, as they can become contaminated with heavier elements produced by nearby stars. There is a narrow window. If you find a primitive star, it means the stars haven’t had enough time to mix, and it must be from the very early days of the galaxy.
One way to find this window is to systematically measure a large sample of galaxies, observe them with JWST, and analyze their chemical composition. Although this requires a huge amount of observation time, Ellis says results could be known within the next few years.
topic:
