James Webb Space Telescope Update

 

The James Webb Space Telescope is able to view the universe in a truly new light. Below, MSc student Madeline Walters takes a look at some of the recent discoveries this new observatory has made. Image above: https://images.immediate.co.uk/production/volatile/sites/25/2022/01/JWST-galaxies-ba2f7b8.jpg

by Madeline Walters

It’s been a while since my last Webb update, but since then the space telescope has been busy! To kick off 2023, NASA released a statement [1] about how the James Webb Space Telescope (JWST) was used to capture the shadows of starlight cast by the thin rings of Chariklo, an ice small body located around 2 billion miles away from the orbit of Saturn. As the JWST observed Chariklo passing in front of a background star, the expected obstruction of that star's light occurred- a phenomenon called occultation- which allowed for the observation of a spectrum of the body’s surface. This showed evidence of crystalline water ice, which was previously only a guess from ground-based observations.
 
However, what surprised astronomers was that the starlight dipped twice rapidly before Chariklo passed in front of it, and then twice again as Chariklo moved away. These rapid dips in light were caused by the two thin rings of Chariklo - the first to ever be detected around such a small body. Since Chariklo is so small and far away, the JWST isn’t able to directly image the rings, but with occultation and the JWST’s heightened sensitivity, there is a hope that the composition of the rings may be isolated from the main body, allowing for further study.
 
Along with being able to get a closer look at smaller and more distant bodies with higher precision, the JWST has been showing us other things at higher resolutions than before. Take for example the side by side comparison of the ‘Pillars of Creation’ photos taken by NASA’s Hubble Space Telescope and JWST:

Image caption: A side by side comparison of the Pillars of Creation taken by the Hubble Space Telescope (left), and the JWST (right). Each image shows the same region taken in different wavelength ranges. The Hubble image is taken in the visible light range with different colors representing different molecules, while the JWST image is taken in the near-infrared range, allowing us to peer through the dust. (https://stsci-opo.org/STScI-01GF44F9Y10HZB8SPV2NZ8H6TZ.png)

On the left we have the Hubble image. This incredible and iconic image of towering cosmic dust in the heart of the Eagle Nebula shows us the primary components of what makes up these pillars [2]. Different gasses are represented by different colors here to allow us to visualize it better: blue is oxygen, red is sulfur, and green is both nitrogen and hydrogen. While the colors aren’t what we would see in real life, the structure is similar, since this is taken in the visible light wavelength range.

Now compare that to the image on the right of the same location taken by the JWST. Why is this different? It’s not just because the JWST has larger mirrors-it also comes down to the wavelength range between Hubble and JWST. Hubble observes in the ultraviolet, visible, and near-infrared ranges, while JWST observes in the near and mid-infrared range. This allows the JWST to pierce through obstructing dust and gas that shows up in the visible range, and show a view of the pillars we aren’t as familiar with, but isn’t any less stunning. More images reveal this difference between Hubble and JWST, such as these images of the Southern Ring Nebula, with Hubble on the left and JWST on the right:

Image caption: A comparison of the Southern Ring Nebula (NGC 3132) taken by Hubble (left) and the JWST (right)Each is taken in different wavelength ranges with different colors representing different gases, showing varying level of detail of the region. (https://stsci-opo.org/STScI-01EVVFSTZYZJJKAB41KA6AJ0HQ.png; https://www.nasa.gov/sites/default/files/styles/full_width_feature/public/thumbnails/image/main_image_stellar_death_s_ring_miri_nircam_sidebyside-5mb.jpg)

With the JWST, we can see in higher detail the rings of gas and dust thrown out by a dying star that we previously could not see in the Hubble image. Hubble has taught us some amazing things about the universe, but with the JWST, we can shed new light (in longer wavelengths) on objects in space previously unseen. Even just a few days ago, the JWST detected a dust storm raging on an exoplanet about 40 light years away [3]. The more we’re able to see, and the further back in time we are able to peer, the more we can learn about the universe and our place in it.

[1] https://blogs.nasa.gov/webb/2023/01/25/webb-spies-chariklo-ring-system-with-high-precision-technique/

[2] https://www.nasa.gov/image-feature/the-pillars-of-creation

[3] https://webbtelescope.org/contents/news-releases/2023/news-2023-105