“Impressive! Incredible!” exclaimed scientists and the general public upon discovering the first images drawn by the James Webb telescope. These shots, taken over the last few weeks, and to say the least spectacular, in fact, reveal details never before glimpsed. Six months after its launch, the world’s most powerful space telescope is working like a charm, even “exceeding expectations”, as these prodigious tests obtained during its operational period show.
A first image was revealed in preview on Monday night at the White House, in the presence of US President Joe Biden. This is the “deep Webb field” image, the deepest and sharpest image ever obtained of the distant Universe in infrared radiation. In this image appears the cluster of galaxies SMACS 0723 as it was 4,600 million years ago, and in which many galaxies of different colors are concentrated, each with different characteristics.
The combined mass of all the galaxies in this cluster also plays the role of a gravitational lens that has made it possible to magnify and highlight much more distant galaxies, which formed less than a billion years ago. It took place about 13.5 billion years ago.
see the unseen
“By working in the infrared, the James Webb Telescope allows us to see further into the Universe than the Hubble Telescope. Due to a phenomenon similar to that of the Doppler effect (which causes the frequency of the sound emitted by a train, for example, to change as it approaches or moves away), the wavelength of the light that reaches us from distant galaxies, which move away more and more of us due to the expansion of the Universe, stretches and is thus in the infrared. To Hubble, which looks primarily at the visible, these objects became invisible. With Webb, therefore, we can go further back in time. We should be able to go back a few hundred million years after the Big Bang,” explains Erick Dupuis, director of space exploration development at the Canadian Space Agency.
The second shot that was revealed to us this Tuesday is rather that of the spectrum of the atmosphere of the exoplanet WASP-96 b located 1150 light years from us and that revolves around a star similar to the Sun.
Pour ce faire, l’instrument canadien NIRISS (imageur et spectrographe sans fente dans le proche infrarouge) a capté le specter de la lumière de l’étoile ayant traversé le petit anneau d’atmosphère entourant l’exoplanète alors que cette dernière passait devant son star. The spectrum thus obtained contains the spectral signature of all the molecules present in the planet’s atmosphere.
However, analysis of the spectrum of WASP-96 b confirmed “unambiguously the presence of water molecules in the atmosphere” of this gas giant slightly larger than Jupiter and with a mass close to that of Saturn.
“This spectrum, which is the most detailed ever obtained for an exoplanet, demonstrates Webb’s ability not only to detect exoplanets, but also to determine the chemical composition of their atmosphere,” René Doyon, Principal Investigator of the Canadian Instruments, enthuses. NIRISS and FGS. (Precision guide detector).
South Ring Nebula
The third image shows two shots of the Southern Ring Nebula, one taken in the near infrared on the left and the other in the mid-infrared on the right. Located 2,500 light-years from us, this nebula is the scene of the last stages of the life of a star, which appears as a small red dot in the center of the image on the right.
“The mid-infrared (on the right) allowed us to distinguish two stars at the heart of the nebula: a redder star that has just died and, when it died, created this so-called planetary nebula. Right next to it, another star, white for its part, is still alive, and it is also visible and bright in the center of the image on the left. However, the red star is almost invisible in the image on the left because it is surrounded by dust. We needed to go even further into the mid-infrared to see it behind the cosmic dust that surrounds it,” explains Nathalie Ouellette, head of science communications for Webb in Canada and coordinator of the Exoplanet Research Institute at the University of Montreal.
For its part, the fourth image shows in a remarkable way the violent gravitational interactions that take place between four galaxies of the Stephan’s Quintet, which includes five galaxies, two of which are about to merge in the cloud on the right. “The Webb telescope allows us to see how the collisions between galaxies induce the birth of new stars in each of them”, emphasizes Mr.me Ouellette while specifying that it is the shock waves of these cataclysms that condense the gases of the galaxies into new stars.
Webb also hinted at the presence of a supermassive black hole in the uppermost galaxy in the image. “If we zoom in on this galaxy, we can see energetic jets that come out of the black hole and that indicate that it is very active”, indicates the astrophysicist. Thanks to the unprecedented level of detail provided by Webb, scientists will be able to determine the rate at which black holes are growing.
In the last impressive cosmic landscape that we were presented with, this time we discovered a stellar nursery called NGC 33245 that is located in the Carina Nebula. “The power of the Webb telescope allows us to see here the beginning of the birth of some of the stars. Birth is a stage in the life of a star that lasts for a very short time, only a few million years, and it is technically difficult to observe such a stage because the star is then completely surrounded by dust. But thanks to infrared light, Webb drills into this dust, allowing us to see the birth of stars that, until now, were impossible to observe,” explains M.me Ouellette.
“All of these images were obtained after just 120 hours of observation during a specific demonstration program. This is only the beginning of what Webb will reveal to us…” emphasizes René Doyon.
The space telescope mission is now entering its operational and scientific phase.
to see on video
#images #James #Webb #telescope #reveal