Less than six months after launching into space, the James Webb Telescope is already starting to unlock the secrets of the universe. Behind these images straight out of a science fiction film, a real scientific leap is underway Sometimes the objects seen did not reveal themselves to the researchers.
Read more: The James Webb Telescope: Why it will revolutionize our knowledge of space?
“These photos are an important shortcut to communicate with the general public. We choose datasets that are pleasing to the eye, allowing us to share the joy of having this device with everyone » Beyond the beauty of the images, Nicole Nesvadba, director of research at the National Center for Scientific Research (CNRS) Côte d’Azur Observatory, explains how these spectacular images open the door to a new world for scientists.
James Webb’s first image, Deepest Image of the Universe
This is the first image from the James Webb Telescope, released to the public by Joe Biden on July 11, 2022. In this shot, which NASA recalls is the deepest image of the universe, we see stars and galaxies. The image is a little distorted because, to get it, scientists used a
Gravitational lens : “Large masses – here clusters of galaxies – change the shape of space, and 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 we are most interested in is the very small red dot that is not very visible,” Nicole points out Nesvadva. These objects are very, very distant galaxies, never observed before. They are so far away that, due to the effects of physics, their color, initially blue, comes to us in red. 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 structure of the universe.
The Southern Ring Nebula, or How Stars Die
Here is a dead star. In the image to the right, in the center of this shot of the Southern Ring Nebula, we can see two stars very close together. “One of them is dying and ejecting layers of matter in the form of gas and dust, forming a nebula.”. These gases are shown in blue in the image on the left. At the periphery of the nebula, dust is shown in red.
“Some stars, when they have consumed all the fuel to run the thermonuclear process, eject their outer parts, which will create these very beautiful structures.”, explains Nicole Nesvadba. This process, which will one day happen to our Sun, takes 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 other star in the center of the image is less evolved. The time of his death has not yet come. “When we say ‘less evolved’, we’re not necessarily talking about age, but above all about mass. » It’s quite counter-intuitive, but low-mass stars live the longest: they don’t burn through their fuel as quickly as massive stars, which are bound to die quickly. A bit like an SUV that consumes its fuel faster than a Twingo.
This slow burn also marks a step toward another generation of star formation: dust ejected during this process, after traveling through space, sometimes for billions of years, can be incorporated into a new star. training
Cartwheel Galaxy: When two galaxies collide at high speed
In addition to its spectacular aspect, the Cartwheel Galaxy is a symbolic object, “extremely observant” By scientists, says Nicole Nesvadba.
Its particular shape is attributed to a high-speed collision between a smaller galaxy (invisible in the image) and a larger one (right) 400 million years ago. The galaxy is made up of two rings: a bright inner ring and a colorful outer ring. They are both expanding, and slowly moving away from the point of collision like a shock wave.
In the picture, red color represents dust. Each little blue dot is a nursery of stars. “The collision triggered a phase of star formation, with new stars forming in the galaxy,” Nicole Nesvadba explains
Below are the differences between Hubble and James Webb telescope observations:
Why is science interested in these objects? “Because although such events are rare, the physical processes behind them are universal. » Aim of astrophysicists: To study the birth of stars. “We still don’t know how they are formed, it’s a bit embarrassing. We understand only the main line. It is one of the most researched fields today. »
“Cosmic Cliffs” in the Carina Nebula: A nursery of stars
Here’s an image of the center of star formation taken in the Carina Nebula, 7,600 light-years from Earth. “Brown ‘little’ fingers are sites where new solar systems are being born”Surrounded by dense dust and gas, researchers observed.
It’s a never-before-seen region, shrouded in dust, that blinded James Webb’s predecessor, the Hubble Telescope.
This rough area and “cavernous”some of whom “peak” Measuring about seven light-years across, it has been sculpted by the intense UV radiation and stellar winds of young and massive stars, as we can guess just out of view in the upper right of the image.
Its warm light destroys and dispels the dust that surrounds it at birth. This is why we observe two distinct regions: once stars form in this dust cloud, they will disperse the gas and destroy the dust, thus giving it the appearance of a blue region. This has already happened for very bright stars. This process takes a million years. “What is interesting is the interface between the blue part and the brown part: these are very complex effects of star formation. » This vaporous region is formed by gas and dust heated by the nebula and its radiation.
Scientists hope to understand why some stars are more massive than others and the role of each of these nebulae.
Stefan’s Quintet: When Galaxies Collide
It is the largest image taken by the telescope: it contains 150 million pixels and is made up of about 1,000 individual images. It shows five galaxies, a group called the Stephane Quintet, named after the Marseille astronomer Edouard Stephane, who discovered it in 1878.
In reality, there are only four of these galaxies
relativesThe fifth is far away. “What is spectacular in this picture is the yellow light, the clarity of starlight.”, note Nicole Nesvadva. A feat made possible by the unique capabilities of the James Webb Telescope.
The proximity between these galaxies allows scientists to study their interactions more precisely, important in their evolution, NASA points out: in this, Stefan’s quintet is like a laboratory to find out how they form stars in them, how the gas interacts, etc. .
According to the US space agency, this type of grouping of galaxies was more common in the early universe. Their matter may have fueled extremely powerful black holes called quasars. One of these galaxies contains a supermassive black hole, 24 million times the mass of the Sun. A black hole has been verified by James Webb, with a level of detail never seen before.
The scientists’ goal: to understand the rate at which supermassive black holes feed and grow.