What scientific discoveries do the amazing images of the James Webb Telescope reveal?

Less than six months after its commissioning in space, the James Webb Telescope has already begun to unlock the secrets of the universe. Behind these images straight out of a science fiction movie, there is a real scientific leap at play. Objects, sometimes never seen, have exposed themselves to researchers.

Also read: James Webb Telescope: why will it revolutionize our knowledge of space?

“These images are an important shortcut to communicate with the general public. We will choose datasets that are beautiful to the eye, it allows us to share our joy of having this instrument with everyone. » Beyond the beauty of the images, Nicole Nesvadba, National Center for Scientific Research (CNRS) research director at the Côte d’Azur Observatory, explains how these spectacular images open the doors to a new world for scientists.

The first image by James Webb, the deepest image of the universe

This deep field is the first image from the James Webb Space Telescope, posted by US President Joe Biden on Twitter. | NASA/AFP

This is the first photograph of the James Webb telescope, unveiled to the public by Joe Biden on July 11, 2022. In this image, which is the deepest image of the universe ever taken, NASA reminds us, we see stars and galaxies. The image is slightly distorted because the researchers used a gravitational lens : “The large masses – here the galaxy cluster – change the shape of space, and the light follows this deformation. Thanks to this effect, you get the equivalent of a magnifying glass. »

This technique has revealed the light of galaxies and star clusters extremely distant and for some never seen before.

A boon for scientists. “What interests us the most are the very small red dots, which are not very spectacular”, points out Nicole Nesvadba. These objects are very, very distant galaxies, never observed before. They are so distant that their color, blue at first, comes to us in red due to a physical effect. their age? About 400 million years, which is the age of the universe.

Scientists will study these galaxies, which are both the oldest for us and the youngest from the point of view of the creation of the universe, formed just after the Big Bang. They will be interested in their properties, their mass, their number, etc. They hope to learn more about the formation of the universe.

The Southern Ring Nebula, or how stars die

In this image, the star (center) has been ejecting gas and dust for thousands of years in all directions, forming a planetary nebula. | NASA/AFP

Here is a dying star. In the image on the right, in the center of this image of the Southern Ring Nebula, we can see two stars very close. “One of them is dying and has ejected layers of matter in the form of gas and dust, forming a nebula”. These gases are shown in blue in the image to the left. In the periphery of the nebula, dust is shown in red.

“Some stars, when they’ve used up all the fuel to run the thermonuclear process, eject their outer parts, which will form these very beautiful structures.”, explains Nicole Nesvadba. This process, which will one day happen to our sun, lasts for tens of thousands of years.

The different rings represent successive layers ejected by the star. Thanks to this image, scientists will be able to go back in time and draw a history of this system.

The second star in the center of the image is less developed. The time has not yet come for her to die. “When we say ‘less developed’, we are not necessarily talking about age, but above all about mass. » It’s quite counterintuitive, but it’s the low-mass stars that live the longest: they don’t burn through their fuel as quickly as massive stars, which are bound to die more quickly. A bit like an SUV that consumes its fuel faster than a Twingo.

This slow pain also marks a step towards the formation of a second generation of stars: the dust ejected during this process, after traveling in space, sometimes for billions of years, could be incorporated into a new star.

Cartwheel galaxy: when two galaxies collide at high speed

Spectacular image of the Cartwheel galaxy, which owes its shape to the collision of two galaxies. | NASA/ESA

Aside from its spectacular side, the Cartwheel Galaxy is a symbolic object, “very observed” by scientists, says Nicole Nesvadba.

It owes its particular shape to a high-speed collision between a small galaxy (not visible in the image) and a large one (right), 400 million years ago. The galaxy consists of two rings: a bright inner ring and a colorful outer ring. They both expand and gradually move away from the point of collision, like shock waves.

In the picture, the red shades represent dust. Each little blue dot is a nursery of stars. “The collision triggered a phase of star formation, with the formation of new stars in the galaxy,” explains Nicole Nesvadba

Below is the difference between the Hubble and James Webb telescope observations:

Why is science interested in this object? “Because even though this type of event is rare, the physical processes behind it are universal. » The goal of astrophysicists: to study the birth of stars. “We still don’t know how stars form, it’s a bit embarrassing. We only understand the main lines. This is one of the most researched areas today. »

“Cosmic rocks” in the Carina nebula: a nursery of stars

Here’s an image at the heart of star formation, taken in the Carina Nebula, 7,600 light years from Earth. “The ‘little’ fingers in brown are the places where new solar systems are born”surrounded by dense dust and gas, the researcher observes.

It’s a never-before-seen region shrouded in dust that blinded James Webb’s predecessor, the Hubble telescope.

This harsh area and “cave-like”some of which “peek” measuring about seven light-years, is sculpted by the intense UV radiation and stellar wind from young and massive stars, like the one we can guess out of sight, at the top right of the image.

Its warm light destroyed and repelled the dust that surrounded it at birth. This is why we observe two distinct zones: once the stars form in these dust clouds, they will disperse the gas and destroy the dust, thus becoming the blue zone. For the very bright star, it has already happened. This process takes a million years. “The interesting thing is the interface between the blue part and the brown part: these are very complex effects of star formation. » This vapor zone is formed by hot gas and dust escaping from the nebula and its radiation.

Scientists hope to understand why some stars are more massive than others and what role they play in these nebulae.

Stephan’s Quintet: When the Galaxies Collide

Stephan’s Quintet, through the James Webb Telescope. | NASA/AFP

It is the largest image taken by the telescope: it contains 150 million pixels and consists of almost 1,000 separate images. It shows five galaxies, a group called the Stephan quintet, named after its discoverer, Marseille astronomer Édouard Stephan, in 1878.

In reality, there are only four of these galaxies next of kinThe fifth is much further away. “The spectacular thing in this picture is the transparency of the yellow light, the starlight”, notes Nicole Nesvadba. A feat made possible by the unique capabilities of the James Webb Telescope.

The proximity of these galaxies allows scientists to study their interactions, which are crucial for their evolution, points out: In this, Stephan’s Quintet is like a laboratory to find out how they cause the formation of stars between them, how interact gas etc. .

According to the US Space Agency, such groupings of galaxies were more common in the early age of the universe. Their matter may have fueled highly energetic black holes called quasars. One of these galaxies is also home to a supermassive black hole, 24 million times the mass of the Sun. A black hole studied by James Webb, with a degree of detail never seen before.

Goal for scientists: to understand the rate at which supermassive black holes give birth and grow.

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