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!

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.

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.

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).

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!

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.