Each of James Webb’s First Five Images Explained
The James Webb Space Telescope (JWST) launched on Christmas Day of 2021. After six and a half months of tweaks and refinements, all the hard work is finally beginning to pay off.
I mean, what a relief that the damn thing didn’t break!
It was a 30 year long project, costing 10 billion dollars. There were 344 points of failure, but thanks to NASA’s brilliant team of engineers all went to plan.
This month, JWST was handed over to the scientists to do their thing. So far, NASA has released five images taken by the telescope. All very unique, but equally as interesting.
1. SMACS 0723
Unveiled by the US President Joe Biden, this was the very first image taken by JWST to be released.
This type of image is known as a deep field, and is essentially a long exposure observation of a particular small region of the sky. The aim is to collect as much light as possible in order to capture the most information and reveal the deepest corners of this portion of the sky.
The name of the image, SMACS 0723, refers to the name of the galaxy cluster which this image is capturing. Although most people just refer to it as “Webb’s First Deep Field”.
Dr Stefanie Milam from NASA explains in the Waveform podcast how the beauty of this image is that it “completely demonstrates what (JWST) was designed and built to do … to study the first stars and galaxies … to probe the infant era of the universe … (this image) is the first step towards approaching that limit”.
So almost every point of light in this image is an entire galaxy, each from different points in time.
The ones which are not galaxies, look like “christmas stars”. As you might expect, these are indeed stars. This fairy like appearance is called the point spread function, and is simply a result of JWST using a hexagonal mirror.
The white galaxies close to the centre of the image are so massive that their gravitational forces act like lenses which bend light. That’s why so many of the galaxies around them look as though they are being sucked towards the them. This is known as galactic lensing.
In total, this image took about 12 hours to capture. That sounds like a lot, but compared to the Hubble Telescope’s comparable deep field which took weeks to capture, it’s really not too bad.
2. Stephan’s Quintet
Most people think this image contains four galaxies. But look closely, there’s five!
The galaxy on the left is much closer to us than the others, hence why it appears to be far more resolved. It seems as though you can pick out all the stars within it.
There are then two on the right hand side which are in the process of merging to form a single larger galaxy.
While the image above is beautiful, I think one of the alternatives on the WebbTelescope.org website is even better.
This alternative, known as the mid infrared image (MIRI), reveals lots of information.
Red generally represents star-forming regions and very distant, early galaxies enshrouded in thick dust. Blue indicates stars and star clusters without dust. Diffuse areas of blue denote dust with a significant amount of large hydrocarbon molecules. Yellow and green represent earlier and more distant galaxies consisting of these hydrocarbons too.
3. WASP-96 b
WASP-96 is a Sun-like star that has an extremely large exoplanet, about the size of Jupiter, which orbits around it with a period of about 3.5 Earth years.
This planet has an incredibly puffy atmosphere so is only half the density of Jupiter. This type of gas giant is often known as a “super-puff”. It’s also very hot, as it’s roughly the same distance from WASP-96 as Mercury is from the Sun.
Clearly, this image is not of said planet. But rather, it is an absorption spectra of its atmosphere.
An absorption spectra analyses light that has passed through a gas. For a given atom in the gas, light of certain wavelengths will be absorbed by it.
So by analysing all the light the has been absorbed or “blocked” as it passes through this planet’s atmosphere, one can see roughly what type of molecules are present.
The spectra shows strong evidence for the presence of water vapour!
4. Southern Ring Nebula
These are two images of a dying star, 2,500 light years away, called NGC 3132.
For a significant amount of their lives, nuclear fusion between hydrogen and helium is occurring at the core of stars. The fusion process releases A LOT of energy, causing the huge amount of light and heat we associate with stars.
However, as they get older they progressively fuse heavier elements. This releases more and more energy causing the star to keep growing and expanding.
All of the ejected elements around the star cool down and form this “cloud of dust”. This obscures the light, changing the apparent colour of the star. At this point, it is known as a giant (either a red giant or a blue giant).
As the star and its cloud keep expanding, the pressure at the core keeps decreasing. Fusion requires a high pressure environment, so eventually the fusion stops occurring.
This leaves a very small centre star, and a huge amount of surrounding material in the form of the dust cloud.
The very small centre star is called a white dwarf. You can see it in the centre of both images.
The white dwarf is so hot that it radiates huge amounts of light. This illuminates the surrounding material it shed off, producing what is known as a planetary nebula. That is what you can see in these images.
The image on the left is the near infrared image (NIR), while the one on the right is the mid infrared image (MIRI).
The MIRI image reveals that this is actually a binary star system (there are two stars). The bright red star on the left of the MIRI image is the one which is dying and causing this beautiful scene.
5. Carina Nebula
This image is regarded by many as the most beautiful of the 5. Known as the Cosmic Cliffs, it resembles “mountains and valleys” on a “moonlit evening”.
You are seeing the edge of a star-forming region called NGC 3324 in the Carina Nebula. It is essentially a giant cloud of gas and dust, and for scale, the tallest “peaks” in this image are about 7 light years high.
There are various dynamic processes within the cloud which cause turbulence and disturbances. In particularly dense regions, this can cause the gas and dust to collapse in on itself, giving birth to stars.
While the “mountainous” region is where stars are forming, the top of the image, or the “night sky”, is where many young-stars have already formed and pulled in all their surrounding gas and dust to create the beginnings of their own planetary systems.
We don’t actually know many details about how stars are formed, but NASA claim that JWST will undoubtedly allow us to discover lots about this.
Hubble’s version of this image is one of its most famous. I love comparing the two side by side, as the increase in quality is absolutely incredible.
Summary
These five images only touch the surface of what JWST can do. Each image was handpicked from a collection by NASA in order to briefly demonstrate the telescope’s potential.
A lot of emphasis was put on taking pictures of objects and events we’ve already observed with the Hubble Telescope, allowing us to see how far we’ve come. Below shows a comparison of Hubble’s and James Webb’s deep field of the SMACS 0723 galaxy cluster.
This technology isn’t just for creating pretty wallpapers. There is vast amounts of information that scientists can discover using this telescope. That said, if you’re not already using Carina Nebula as your wallpaper, you should be! You can download all the high resolution images from NASA’s website.
https://www.nasa.gov/webbfirstimages
Sources
- https://flyingbarron.medium.com/the-james-webb-space-telescope-making-300-points-of-failure-reliable-db669810a9d8
- https://www.bbc.co.uk/news/science-environment-59419110
- https://esahubble.org/science/deep_fields/
- https://webbtelescope.org
- https://www.youtube.com/watch?v=53XRRScxyxo
