The first images from the James Webb Space Telescope have kept all their promises and amazed the general public and the scientific community with their beauty and unsurpassed level of detail. But what exactly do they show, and what do we hope to learn from them?
– Southern Ring Nebula –
One of James Webb’s goals is to study the formation and life cycle of stars, and for this, mists, giant clouds of gas and dust, are a primary goal.
The southern nebula surrounds a dying star. It is located about 2,000 light-years away in our galaxy, the Milky Way.
“At the end of its life, with each pulsation, this star has emitted some of its material,” explained AFP Pierre Ferruit, scientific co-director of the European Space Agency (ESA) telescope. “And what’s left in the middle is the core of this star, which we call a white dwarf: a very small, very hot star.”
The orange rings around it represent the gas that was ejected from this central star. New stars could be born from it.
Another image of the same nebula, taken by James Webb at a different wavelength, clearly revealed another star in its center for the first time.
– Carina trains –
Also in the Milky Way, the Carina Nebula is a giant star-forming area about 7,600 light-years away.
The image consists of “an area at the top that contains very little gas and dust, and one at the bottom with these breathtaking dust structures”, commented Pierre Ferruit. Some “very red” stars are also visible, “which are actually in the heart of the dust”.
The snapshot reveals hundreds of stars never seen before, but also galaxies in the background and structures still unknown.
The orange color comes from hydrocarbons, very large molecules, explained Klaus Pontoppidan, chief researcher for James Webb. “This could be the universe’s way of transporting carbon (…) to habitable planets,” he said.
– Stephan Quintet –
Stephan’s Quintet is a compact group of galaxies, 290 million light-years away.
It includes five galaxies in total, four of which interact with each other, in a true cosmic dance. Two merge.
Such observations should make it possible to learn more about how “galaxies collide and merge,” cosmologist John Mather, the Nobel Prize in Physics and one of James Webb’s scientific fathers, told AFP. Our own Milky Way “was probably assembled by a thousand small” galaxies, he remarked.
The image also contains a black hole, which in itself can not be seen, but which can be guessed at by the material that is sucked up around it.
– Clusters of galaxies –
This very first snapshot revealed includes no less than thousands of galaxies, some of which were formed shortly after the Big Bang more than 13 billion years ago. One of James Webb’s main missions is to explore the early ages of the universe.
The galaxy cluster called SMACS 0723 is shown here as it was 4.6 billion years ago. But by acting as a magnifying glass, it also made it possible to detect very distant cosmic objects behind – an effect called gravitational lenses.
This is James Webb’s first “deep field”, ie a picture taken with a long exposure time in order to detect the faintest glimpses. Here 12.5 hours. It only scratches the surface of the telescope’s possibilities in this area.
– Exoplanet WASP-96 b –
Another main line for James Webb: exoplanets, that is, a planet in orbit around a star other than our sun.
This last image is not a photograph, but a spectrum, that is, an analysis of the light emitted by an object, which makes it possible to determine its chemical composition.
WASP-96b is located 1,150 light-years away. It is a “hot Jupiter”, but with half the mass.
By observing the light that passes through the atmosphere of this planet as it passes in front of its star, James Webb discovered water molecules there. But also for the first time clouds.
Next step: to determine the “amount of water present and the implications for the overall composition” of its atmosphere, said Knicole Colon, an exoplanet specialist at NASA’s Goddard Space Center.
More than 5,000 exoplanets have been discovered since 1995, and scientists are searching for another world that promotes the evolution of life.