On December 25, 2021, the space telescope left for space James Webb. From a privileged observation point, in an orbit 1.5 million kilometers away from Earth, protected from solar and terrestrial radiation, it promises images capable of transforming our image of the universe and questioning our place in it. On a visit to the European Space Astronomy Center of the European Space Agency, near Madrid, Chris Evans (Hertford, United Kingdom, 47 years old), responsible for ESA representation at the institute that manages the Webbreviews some of the discoveries of this 10 billion euro artifact two years after its launch.
What is the cosmos made of?
He Webb captures five times more light than the space telescope Hubble. This allows it to detect weak signals from distant planets or galaxies shortly after the Big Bang, but thanks to its spectroscopic capabilities, which decompose light and measure the wavelengths emitted by each object, it can know its composition. “Even though you see all these pretty images being published, three-quarters of the observing programs are for spectroscopy,” explains Evans. With these images it has been possible to detect, for the first time, carbon dioxide in the atmosphere of an extrasolar planet, in WASP 39b, and it will be possible to analyze the effects of the flares launched by red dwarfs, the most frequent in the universe, on the atmospheres of the planets that surround them. This is an important step to find out if life may have developed on these abundant worlds, but subject to a hostile star.
It will allow you to ask previously impossible questions
“If we look at galaxies that are relatively close, like 20 million light years away, with the Hubble you can observe these beautiful and iconic spiral galaxies. You can see the light from the stars and the spiral arms, and you also see the dust lanes, where there is a lot of interstellar gas and dust that obscures the light that the Hubble observes in the ultraviolet, visible light range and infrared. But now, [con el Webb]we have observations with longer wavelengths, and we can see inside that dust, and we can reach regions than before, with the Hubble, were not accessible. We see the backbone of galaxies, a lot of star formation inside them and all the galactic material. If you are interested in understanding how stars form and the history of these galaxies, the Hubble It gives you a good starting point, but there are a lot of parts that you miss because they are in these dark regions.”
Everything happened very quickly after the Big Bang
One of the capabilities of Webbwith its NIRCam (near-infrared camera) camera, is to make images of the deep universe, beyond what the Hubble. With its sensitivity and longer wavelength, it can reach galaxies that were forming when the universe was less than 1 billion years old, 7% of its current age. There they have found strange objects, such as small red dots that are apparently very massive, perhaps too massive for that stage of the universe. “In some of these galaxies we are seeing evidence that they have supermassive black holes at their centers, just hundreds of millions of years after the Big Bang, and there is a lot of excitement in the scientific community trying to understand how such massive objects could accumulate so quickly. ”says Evans.
“We know that it is something that happens in galaxies, but seeing it at such an early stage makes us wonder how such rapid chemical enrichment has occurred. You need many generations of very massive stars, burning up their fuel very quickly, exploding as supernovas, and releasing all that enriched material. [con nuevos elementos] to be processed again again and again until building the chemistry that we see in these distant galaxies,” adds the astronomer. All of this is changing our way of understanding the evolution of galaxies.
In search of habitable planets
Evans acknowledges that to find signs of life on an Earth-like planet next to a Sun-like star “it will be necessary to wait for a next-generation facility.” However, in the early works of Webb With exoplanets like those orbiting the red dwarf Trappist-1, a system with seven Earth-sized planets next to a very different star, it has already been seen that one has no atmosphere and another has a very thin one, and The study of the most distant planets continues. We are beginning to understand the diversity of worlds in the universe and what conditions there may be for life in very different places on our planet. “Looking at other planetary systems teaches us that the Earth is in a very special place,” says the astronomer.
“We recently published a study of a disk around a forming star that is in a larger star-forming region with a large number of massive stars. We used to think that if you had all these massive stars, there would be strong fields of ultraviolet radiation, which would disperse the gas and break the chemical bonds necessary for planet formation. But this team from Max Planck in Heidelberg (Germany) saw that in one of these disks, with that environment, there was a rich spectrum of molecules, carbon dioxide, cyanide or even water. “This is very exciting, because we think that most stars form in these regions and this means that there may be more rocky planet systems than we would expect,” says Evans.
The interior of the Solar System and the origin of water on Earth
There is a complementarity between the work of space telescopes such as Hubble either James Webb and missions that visit other planets in the Solar System. Probes take very detailed measurements, but telescopes can do more continuous monitoring. According to Evans, within our planetary system it has also been possible to study the presence of water in the comet belt beyond Pluto and the asteroid belt between Mars and Jupiter. “We have seen water coming out of an asteroid as it approaches the Sun. It seems like a small detail, but it is a critical part of understanding how water got to the inner part of the Solar System and could explain the water in our oceans or the chemistry of the planet. ”Evans points out.
A lens to see the first stars
One of the aspects highlighted by Evans are the images of the deep universe that the Webb. “We deliberately target galaxy clusters that, due to their gravitational pull, act like a large lens that magnifies the objects behind them,” explains Evans. “This is how you see all these warped galaxies that allow you to see them in a magnified way and reach objects that are too faint or too far away that could not be seen otherwise,” he adds. This technique allows us to capture the light of the first stars born after the Big Bang and all kinds of exotic objects.
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