2023-09-05 14:23:00
Entering service in July 2022, the James-Webb Space Telescope (JWST), built by the American (Nasa), European (ESA) and Canadian (CSA) agencies, continues to deliver breathtaking images of space and incredible data on the history of stars. Placed in orbit 1.5 million kilometers from the Earth, this technological jewel multiplies the shots with unparalleled precision. Thanks to its infrared observations, unlike its predecessor Hubble still in operation, it sees through interstellar dust and gas, and detects the most distant planets and galaxies. A real machine to go back in time in the direction of the “cosmic dawn”.
The performance of JWST (Webb, for insiders) is up to expectations and these twenty years of research to develop it and these 10 billion dollars of investment to manufacture it. As soon as it was started, it offered the snapshot of the first deep field of the Universe, the furthest from the Earth ever photographed, revealing galaxies formed only a few hundred million years after the big bang (13.8 billion of years).
Then it delivered highly accurate color images of a stellar nursery, a group of interacting galaxies and an expanding planetary nebula. In October 2022, JWST gave its first shot of the iconic “Pillars of Creation”, huge structures of gas and dust where many stars form in our Milky Way, 6,500 light-years from Earth.
Ever more accurate data
In April 2023, Webb turned his attention to Jades-GS-z13-0, the most distant galaxy ever detected (formed 320 million years after the big bang). And, in July 2023, to celebrate the anniversary of the first shots of JWST, NASA delivered the spectacular image of the birth of about fifty stars of a size similar to our Sun, in the nearest nursery. from Earth, 390 light-years away, in a nebulous mass of gas known as the Rho Ophiuchi cloud.
And a month later, Webb continues with an impressive photograph of the Lyra Nebula and the magnificent spectacle of a dying star. “In just one year, the James-Webb Telescope has transformed humanity’s view of the CosmosNASA Administrator Bill Nelson said in a statement. Each new image is a new discovery, allowing scientists around the world to ask and answer questions they never could have imagined before. »
But Webb isn’t just a tool to dazzle astronomers with its jaw-dropping images. The quality of the spectral data it collects also makes it possible to analyze exoplanets, those planets outside the solar system, like never before. The telescope has four instruments designed to study their atmosphere and, potentially, detect signs of biological activity there: the NIRCam camera and three infrared spectrometers which notably measure the distribution of complex radiation.
A device which made it possible, in June, to detect, for the first time, a crucial organic molecule in a planetary system in formation in the Orion nebula, at the heart of a set of gases and dust rotating around a dwarf star.
“This discovery will help to understand where the molecules present in the Solar System come from”, welcomes Olivier Berné, researcher at the Institute for Research in Astrophysics and Planetology, first author of the publication. This molecule is, in fact, a fundamental building block of organic chemistry, the methyl cation, made up of one carbon atom, three hydrogen atoms and one missing electron, this molecule being positively charged (CH3 +).
The international research team, involving scientists from CNRS laboratories, succeeded in flushing it out thanks to the JWST’s Miri spectrometer, which made it possible to “to detect a particular signal, specific to the emission of this molecule”says Olivier Berné. “CH3+ is a very simple moleculehe says. Astrophysicists predicted its importance for the chemistry of carbon in space in the 1970s. But it took fifty years to confirm that it was indeed present…”
Proof of the existence of dark matter?
In just one year, the JWST has pushed the frontiers of knowledge in key areas, opening up new perspectives – and questions – to researchers. How could supermassive black holes, observed at the edge of the Universe, grow faster than galaxies? How to explain that the planets of the Trappist-1 system, organized around a brown dwarf located in the constellation of Aquarius, probably have little or no atmosphere? Crucial questions, arising directly from the discoveries made by Webb.
The telescope still has many surprises in store. In July, a team of American astrophysicists working with the JWST spotted three stunning, large, “shining” stellar objects that could make one of the most important discoveries of all time. They could be the first “dark stars”, celestial objects whose existence, for the moment, is only theoretical. Why “black”? Because these stars would be fed not by collisions between particles made up of normal stellar matter (nuclear fusion), but by particles of “dark matter”.
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This element, of which only the gravitational effects are perceptible to us, would constitute nearly 30% of the Universe and would play a major role in the formation of galaxies. According to the theory, the massive particles of dark matter, colliding, would obliterate in mutual destruction, giving rise to an explosion of heat and light, fuel for the stars being born.
This dark star model would explain in particular how a large number of hypermassive galaxies became so large in such a short time after the big bang. At this point, new, more detailed observations are needed to validate the hypothesis. But young Webb still has time. It seems, NASA is told, that the telescope has enough fuel to operate for twenty years…
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