James Webb Space Telescope - First Images

July 13th 2022 by Anand M

The first public images from the James Webb Space Telescope (JWST or Webb for short) were released early this morning (13th July 2022). It has been 20 years since I heard about this telescope, and I’ve been waiting for them. I’ve waited to see them for their science, beauty, and what they tell us about our universe. Today I feel privileged to view them and spend time talking about them with the world. 

Too often in science, we ask why, what’s the point of this. I generally seem to think why not. The beauty of our universe needs to be appreciated and celebrated. Learning more about the universe helps us better appreciate our little place in it. We have always looked up and wondered what is out there, and now, thanks to the James Webb Space Telescope, we know a little more. So let’s take a closer look at each image.

James Webb Space Telescope Caricature

Deep Field Image - Looking into the past

Deep Field

This first image was released early by US President Biden and shows a galaxy cluster SMACS 0723 (a galaxy cluster is a group of galaxies held together by gravity). The image is taken from only 12.5 hours of observation, with the JWST pointing at a point in the sky the size of a grain of sand that would typically look empty. It isn’t empty. The galaxy cluster also acts as a gravitational lens to allow us to observe galaxies from the distant past. There are galaxies in the image where the light has taken 13.1 billion years to get to us; this light left the galaxy when the universe was only about 700 million years old. We are looking into the distant past. To learn more about gravitational lensing, refer to the section below.

This image used two of the main instruments of the JWST:

  • NIRCam (Near InfraRed Camera) - which can observe at wavelengths close to visible light (just below red light).
  • MIRI (Mid InfraRed Instrument) - which can observe at wavelengths much lower than visible light in an area that we have never been able to look at with this level of detail.

Together they allow us to look at a patch of the universe in multiple wavelengths to get more information than we ever could get with a single instrument. 

So many galaxies, so many stars, so many planets, it makes you think!

Southern Ring Nebula - A look behind the dust

Southern Ring Nebula

The James Webb Space Telescope (JWST or Webb for short) looked at the Southern Ring Nebula (NGC 3132) using two infrared instruments (NIRCam and MIRI) to see through the dust that usually obscures what’s hiding at the centre (more info on how later in the article). The combination of the two instruments allows us to see more detail and the hidden second star!

We’re seeing a binary star system (two stars orbiting each other, yes, think Tatooine) ejecting lots and lots of dust and gas. In the first image, you cannot see the second star as it is hidden by dust, but by looking at the star at a longer wavelength (the mid-infrared, thanks to MIRI), we can look behind the dust and see the other star. 

The binary star system we see is a widespread arrangement in the universe, and these pictures allow us to study the lifecycle of stars. A white dwarf is the remnant of a dead star (like our Sun). It is no longer undergoing nuclear fusion and is just a hot object that is very dense and so has an enormous gravitational pull. When these stars die, they explode and produce a planetary nebula (which is what you see here). The companion star is now also in trouble with its atmosphere being pulled away by the immense gravity of the white dwarf star, and was previously hidden behind dust, but not anymore! 

The Carina Nebula - Stellar Nursery

The Carina Nebula - Stellar Nursery

 

Again JWST's ability to peer through dust allows us to see regions where stars are born. This image is spectacular; it shows the ‘cosmic cliffs’ are seven light-years high. Throughout them, you see young stars shining for the first time. Webb can do this as it can look through the dust and image these stars in infrared. 

Not only can we see new young stars, but we can also see protostars; these are regions where the star has yet to form, but the dust and gas clouds are starting to collapse into a star. In this one image, we see the early life of stars. Some are incubating within the gas clouds, while others are about to shine for the first time, pushing away the gas clouds around them, others are now undergoing nuclear fusion and are new stars. This image confirms our ideas about stellar evolution and how a star is born.

Stephan’s Quintet - Galactic Evolution

Stephan’s Quintet - Galactic Evolution

This image is Webb’s biggest; it shows five galaxies all interacting with each other. We see them at different stages of their lives. Just like stars, galaxies evolve. We can observe these galactic interactions and see how they change the course of each of the galaxy’s futures. When galaxies collide and interact, there is a burst of new star formation. Understanding how this occurs gives us insight into our future as well since in the next 5 billion years, our galaxy, the Milky Way, will collide with our neighbour Andromeda. 

This image also allows us to study how the supermassive black holes at the centre of these galaxies evolve. Recently the Event Horizon Telescope (EHT) was able to image the black hole at the centre of our galaxy and the one at the centre of M87 and helped to confirm our ideas of black holes. These new images from Webb will help us understand how these supermassive black holes grow and what that means for their host galaxies. 

Spectra of WASP 96-B - Clouds on a distant world

Spectra of WASP 96B

 

While not a pretty picture, the spectrum of light (infrared light) from the exoplanet WASP 96-B. Think of spectra like the colour of the rainbow you see through glass or a prism. White light is made up of many colours, we can extend this, and the light from stars (like our Sun or WASP 96, the star that WASP 96b orbits) is made up of all parts of the spectrum (all colours and all parts of infrared). Molecules like water are good at absorbing specific wavelengths. That’s how your microwave works; water molecules are good at absorbing microwaves (which are longer wavelengths than infrared). 

When these wavelengths are absorbed, they appear to be missing from the spectra. The absorption of the spectra allows us to infer what molecules are in the planet's atmosphere. This technique will allow us to find exoplanets with atmospheres like our own.

Spectra

While Hubble was also able to do this, Webb provides a more fine-grained and higher-quality spectrum to see the presence of water and other molecules. This spectrum is the starting point for comprehensive research into exoplanets. Webb will spend lots of time looking at what’s in the atmosphere of exoplanets to see if the Earth is unique or whether there are other planets with similar atmospheres.

Hubble vs. James Webb

Hubble VS JWST Deep Field

Unlike the Hubble Space Telescope, the JWST looks mainly at the infrared part of the spectrum rather than visible and near UV light. Webb has the advantage of seeing into the distant past and through the dust clouds (for more information on how it does this, refer below).

The comparison below is striking; this is the same part of the night sky that was taken with the Hubble Telescope and then the James Webb Space Telescope. The sheer number of galaxies we can now see is one thing, but the detail is what amazes me. It’s important to note that this image is only 12.5 hours of observation; typically, images like this for Hubble take many weeks or months of observations to get, so this is just a taste of what we’ll be able to learn.

Gravitational Lensing

The first image shows the effects of gravitational lensing. Gravitational lensing is a technique that we use to observe distant objects by taking advantage of the curvature of space-time. Einstein’s theory of General relativity allows us to use large massive objects such as the galaxy cluster as a lens to bend the light from distant galaxies (and other objects). In this way, we’re able to see objects much further away. In the deep field image, we see the effects of gravitational lensing in the slightly curved galaxies that almost look like the light bends around them, just like looking at an object through a glass of water or a magnifying glass.

Those areas that are smeared out are some of the most distant objects that we’ve ever seen! We observe those galaxies as they were almost 13 billion years ago (a cosmological redshift of about z=8); today, they are just over 25 billion light-years away, and their light will never reach us thanks to the accelerated expansion of the universe. We’re getting a glimpse into the past, of how our universe looked when it was just forming.

Gravitational lens

Why look at Infrared?

An Expanding Universe

Edwin Hubble showed that the universe is expanding; later, scientists, including American-Australian Prof. Brain Schmidt from the ANU, showed that the universe's expansion is accelerating. The expansion means the light that we see from distant sources is stretched out due to the Cosmological Red-shift, a type of Doppler Shift (similar to why the pitch of a police siren changes as it moves towards and then away from you). 

Infrared Detail Spitzer vs JWST

As objects move away, the light stretches out, and we observe longer wavelengths. So instead of seeing the light, that is, yellow (580 nm), we would see it red-shifted depending on how far away it is. For example, if it were 7.7 billion light-years (1 light-year is the distance light travels in a year) away when the light was emitted, we would see the yellow light with a wavelength of 1,160 nm, which is in the infrared region of the spectrum. Interestingly that same object that was 7.7 billion light-years away is now 10.1 billion light-years away due to the continual expansion of the universe. This means to detect and understand these distant (and ancient) objects; we need to look in the infrared. This is one of the reasons why the JWST looks at Infrared rather than visible. But we can correct for this Doppler shift and still get lovely ‘true’ colour images as we’ve seen.

Peeking behind the dust

When you look at a wall, you can’t see through it. However, an infrared camera could see through it as the infrared waves can travel through the wall, whereas light waves cannot. When you look at the Milky Way in the night sky, you’ll often see dark areas; these are the great dust clouds in our galaxy. Visible light can’t penetrate them, but infrared light can! We’ll be able to get a view of star formation, solar systems forming and much more! 

Looking through dust

Higher Sensitivity

Our previous space-based infrared telescope was the Spitzer Space Telescope, launched in 2003. It provided us with a tremendous amount of information about the universe. But the main issue was its location and sensitivity. Spitzer was located in an Earth trialling orbit but was still impacted by noise (in the form of heat) from Earth and the Sun despite its Sun shield. Webb’s sun shield and the location at the L2 Lagrange point make the reduction in noise significant. Also, the instruments used on Webb are far more accurate and sensitive. The spectra produced are more detailed, enabling us to gather and learn more about our targets. 

Infrared Detail Spitzer vs JWST

Now what?

These four images and one spectrum are just the start! Hubble has graced us with images for almost 25 years; we can only hope that discoveries from the James Webb Space Telescope will just keep coming. 

The desire to know more is something of benefit to us all. It might not seem obvious as to why, but the technology and scientific developments along with the discoveries from the James Webb Space Telescope will impact us far into the future. 

What we’ve seen in these images are a once in a generational advancement. It is something that shows the power and potential of science and technology. It does affect us; it allows us to see where we are, how we got here, and where we are going. 

We can now truly start to unfold the universe.

 

Image Credits

  • RELEASE: NASA, ESA, CSA, STScI
  • Louise Zhang.