Two experts decipher the first images of the James Webb Space Telescope, and explain what we've learned
Today we take a look at the release of the first batch of images captured by the James Webb Space Telescope. This is something we have both been waiting for for almost 25 years. Back in those days, we analyzed the first Hubble images of the distant universe, and the details they reveal are staggering compared to anything we’ve seen in ground-based images.
It seems the bar has been raised once again, and Webb is set to herald a new era for astronomy and space research. Its large mirror helps it produce images that are two to three times sharper than Hubble’s, and that go much deeper into space (which means it can see dimmer sources).
Webb was also able to see far redder infrared wavelengths, opening up new views of the universe. This is particularly important for studying the early universe because of “cosmological redshift,” a process that refers to the stretching of light (with the expansion of the universe) as it travels through cosmic space.
It’s also useful for studying interesting sources such as planets surrounding nearby stars, and regions where stars form.
We’ve written previously about the tremendous technical challenges involved in building the Webb and its journey into orbit. Now, with the long-awaited first images in our hands, let’s see what they show.
Read more: NASA’s James Webb Space Telescope has reached its goal, 1.5 million km from Earth. This is what happened next
Intense clarity
In passing, US President Joe Biden yesterday presented the first images of Webb’s “inner field”. This is the massive galaxy cluster SMACS-0723 containing thousands of galaxies clustered around a super-bright galactic center crouched in the center.
NASA, ESA, CSA and STScI
You’ll soon see many longitudinal arcs, representing background galaxies that have been “gravitally lensed” as a result of the cluster’s mass. In other words, the large gravitational force at play has caused the light from the galaxy to be distorted (stretched) and amplified, providing a greatly enhanced image of the distant universe.
The clarity is astounding, especially in terms of lens image structure. Here’s a zoomed-in view of a small region, compared to a similar time-exposure image from Hubble:
Adapted from images by NASA, ESA, CSA, and STScI
The enlarged image above depicts a region of deep terrain containing a spiral galaxy that astronomers refer to as “Snails”. It is located several times further than the SMACS-0723 cluster.
But our eyes are drawn more to the very thin bow directly above (marked by an arrow). This little piece shows Webb’s power. This bow was barely detectable by Hubble, but Webb saw the “beads on the string” clearly. They are likely individual star clusters in small, very distant galaxies.
We can see equally amazing details throughout the deep field. For a point-like object, Webb is estimated to be 100 times more sensitive than Hubble, and this clearly shows that.
The field was also littered with some faint red objects, which had already caught the attention of experts. Some of these have the potential to be the most distant galaxies, where light takes the longest to reach us.
Uncover hidden elements
Webb is also able to perform highly sensitive infrared spectroscopy, in which light is broken down into wavelengths to reveal the composition of an object.
While Hubble is terrible at this, Webb manages to do well – shown below by the large planetary spectrum WASP 96b. Located about 1120 light-years away, this planet weighs about half the mass of Jupiter.
NASA, ESA, CSA and STScI
Decreasing the spectrum reveals the presence of water vapor in the planet’s atmosphere. Now, WASP 69b is unlikely to harbor life due to its proximity to its parent star. But the demonstration is very interesting because the same method can be applied to the 5,000 or so other known exoplanets.
With spectroscopy, we will eventually be able to detect potential signs of life such as ozone and methane.
Seeing dust and gas
The third image is of the Southern Ring Nebula, about 2,000 light-years away in the Milky Way. This image shows Webb’s mid-infrared capabilities (which are again well beyond Hubble’s reach).
NASA, ESA, CSA and STScI
This is a classic example of a “planetary nebula” (wrong name because no planets are involved) in which the central star has turned into a small white dwarf by blowing off its outer layers. It occurs at a speed of about 15 kilometers per second, sending out rings of gas and dust.
The brightest star in the center is actually a companion star, and the white dwarf is the faintest pair that can only be seen in the middle-infrared because it is covered in dust. Mid-infrared also highlights dust that forms in the expanding gas.
The fourth image below shows us Webb’s view of the nearby galaxies. Here we see a famous galaxy group called Stefan’s Quintet, located about 290 million light years away. Five galaxies are in close proximity. The four interact with each other and trigger the formation of abundant stars.
NASA, ESA, CSA and STScI
Red lines and clumps indicate the location of new star formation through the associated dust. Details of the dust distribution and the tug-of-war between the galaxies jump out of the picture. And the mid-infrared reveals light from the supermassive black hole at the center of the upper galaxy.
Also notable is the vast sea of distant galaxies in the background. We expect to see this in every Webb image, even as Webb points to a source within the Milky Way. That’s because infrared light passes through the dust. Webb’s infrared detection ability is so sensitive that it can see right through objects within our galaxy.
This means distant background galaxies will blow up every photo of Webb’s image. See if you can see it in the pictures of the South Ring and Carina.
And finally, we have Webb’s homage to the famous Hubble Pillars of Creation image.
NASA, ESA, CSA and STScI
This infrared view shows the Carina Nebula, a gas and dust nursery 7,600 light-years from where new stars are forming and destroying their birth clouds.
The images are extremely complex, and the intricate swirls of dust, gas, and young stars are simply stunning. It may take astronomers years of hard work to figure out what’s really going on here.
Just a handful of these preview images, several days of work for Webb, have provided astronomers with an enormous amount of new data that will fuel years of research. And that’s just the beginning.
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