The revelations of JWST's first scientific images kicked off yesterday when the White House shared the deepest and highest-resolution infrared view of the universe ever, starring the SMACS 0723 galaxy cluster and a lot of gravitationally lensed background galaxies whose light comes to us from the cosmic dawn. That included determining the chemical composition of the furthest galaxy yet. Now, we have the remaining four and we have never seen the infrared universe like this.
NASA, together with the European and Canadian Space Agencies, have released the first observations of the other targets for the biggest and most powerful observatory ever launched into space. Yesterday’s event covered the early universe, and today is about the first images from the other Science Themes that have been chosen for the telescope: galaxies over time, stars' lifecycles, and last but certainly not least, other worlds out there.
SMACS 0723
This is the highest resolution image of the infrared universe ever taken. The choice of SMACS 0723 as one of the first targets makes sense given that it fits perfectly with JWST's study of the early universe.
SMACS 0723, a galaxy cluster known for its incredible mass, is located 4.6 billion light-years away. It is a perfect gravitational lens for the galaxies that existed 13.5 billion years ago, visible in the image as arcs or multiple images of the same galaxy.
Carina Nebula
Nebulae are the birthplace of stars, and the Carina Nebula is one of the brightest and largest in the sky. It is located 7,500 light-years from Earth and is one of the most studied nebulae out there. But that doesn’t mean it doesn’t need a fresh look. And what a look.
The JWST image focuses on a region known as the cosmic cliffs, a "coastline" made of vast strands of gas and dust where star formation is happening against a blue ocean of background stars.
JWST infrared observations have highlighted the tumultuous inhabitants of the nebula. Carina is a stellar nursery, where stars are born. In a region stretching over 100 light-years, there are 1,000 stars the mass of our Sun, and at least 70 with masses between 15 and 150 times the Sun. These massive stars are among the most active members of the nebula and have shaped this celestial structure significantly. The ultraviolet light of these hottest, biggest stars sculpts the dust of the nebula and the dust reemits the light as infrared, seen in breathtaking detail by JWST.
Southern Ring Nebula
Stars are born in the dust and gas of nebulae, and they can turn back into them at the end of their life cycles. A splendid example of this is the Southern Ring Nebula, a planetary nebular located about 2,000 light-years away. The name planetary nebula is a bit of a misnomer, coming from 18th-century astronomers William Herschel and Antoine Darquier de Pellepoix, who both described such objects as resembling planets.
These nebulae are created when a red giant star, later in its lifecycle, releases its ionized gassy outer shells. For the Southern Ring Nebula, the red giant is already gone and what’s left behind is a white dwarf, its degenerate exposed core. It is orbited by a companion, which the mid-infrared image (below) reveal to be shrouded in dust. The white dwarf has a temperature in the 100,000s kelvins hot enough to make the nebular fluoresce under the intense ultraviolet light. The infrared observations from JWST bring a new detailed understanding of the structures of the nebula, showing waves in the shells.
Stephan's Quintet
If one wants to understand galaxy evolution, a crucial process is galaxy interactions, and one of the finest examples of this is Stephan’s Quintet, a visual grouping of five galaxies that was first observed by Édouard Stephan from the Marseille Observatory back in 1877.
Out of the five galaxies, four are actually a real group in space making it the oldest known compact galaxy group. These galaxies have spent billions of years interacting, flying by one another, and merging. The complex system will eventually become a single object turning it into a single massive elliptical galaxy. The four galaxies in Stephan’s quintet are located 290 million light-years away.
Given how many players there are in this system, there is a lot to study here and this beautiful image from JWST already highlights future areas of interest for scientists trying to understand how galaxies change over time. The image above is a mosaic of 1,000 separate image files combined and the full version at 150 million pixels is the biggest JWST image to date.
Exoplanet Spectra
Among these glorious images, the spectrum of exoplanet WASP-96b might almost go unnoticed but the data is a taste of what this observatory can achieve in the study of distant worlds.
The spectrum shows the composition of the atmosphere in exquisite detail event at 1,150 light-years from Earth, confirming the presence of water vapor.
WASP-96 has a mass half that of Jupiter but it orbits its star in just 3.4 days. Back in 2018, it was determined this was the first cloudless exoplanet but the water signature suggests the presence of hazes and maybe hot water vapor clouds.
And this is it. The beginning of the scientific work of JWST. From the very distant light from gravitationally lensed galaxies to the cloudless sky of a (relatively) nearby world, our best infrared eye on the universe is now open.
