Making sense of the James Webb Space Telescope images

https://www.nasa.gov/webbfirstimages — The Carina Nebula

If you haven’t already heard — The James Webb Space Telescope, a 10 billion dollar window into the far reaches of the universe, has released its first images on the 12 July 2022. Behind the beauty of these images. What exactly do these images show?

SMACS 0723

https://www.nasa.gov/webbfirstimages — SMACS 0723

SMACS 0723 — a cluster of galaxies about 4 billion lightyears from Earth in the constellation Volans, the image above corresponds to the area of a grain of rice held up at arms length from an observer on Earth. This galaxy cluster has already been photographed by the Hubble Space Telescope however this image is much dimmer and took weeks of exposure timer compared to the JWST exposure time of only 12.5 hours. The JWST also offers a much more detailed look into this patch of the sky comparatively.

There are a number of features of this image that are interesting :

  • Due to the higher resolution and brightness of the image, a lot more other galaxies and stars can be seen than in the Hubble equivalent image.
  • Around the centre of the image there seems to be a distortion, a sort of fisheye lensing effect. This is caused by gravitational lensing — the light is being bent by the curved space time around a very large mass or area of mass, the mass here being the galaxy cluster as seen as a misty haze in the centre
  • the distorted shapes around the galaxy cluster are actually other galaxies and stars behind the galaxy cluster. In addition to this, these galaxies are very distant very old structures as their light appears redshifted. Around 13.1 billion years old in fact. These details are much more apparent in the JWST image than Hubble.
  • The bright spiky points in the image are nearby stars. Interestingly, the eight points are a result of the arrangement of the mirrors on the JWST. The image of SMACS 0723 from Hubble has instead four pointed stars due to its different mirror arrangement.
  • Every oval shape in the image is its own galaxy. The swirling arms of some of the galaxies can even be seen in some of these.

Southern Ring Nebula

https://www.nasa.gov/webbfirstimages — The Southern Ring Nebula

Also known as NGC 3132, This is an image of a planetary nebula around 2500 light years away from us. a planetary nebula is a nebula where a cloud of ionised gas is ejected from the star’s outer layers in its final stages forming a ring. (It has literally nothing to do with planets)

However NGC 3132 is a binary star system and only one of the stars is dying. the dimmer star (a white dwarf) as seen as the dim red dot on the right image (MIRI or Mid InfraRed Image). This is the star that is responsible for the huge cloud of gas that emanates from the star system. It is much dimmer than its counterpart and can only be seen when imaged in mid infra red light sensors

  • The different layers of gas in the ring around the stars correspond to the different gas layers of the red giant that is now the white dwarf
  • The blue in the centre of the near infrared image (the left image) is ionized super heated gas
  • The ring takes its shape from its interaction with the much brighter, much younger star
  • On the mid infrared image, the blue outer rings represent hydrocarbon grains. They have a similar structure to the orange molecular hydrogen parts of the near infrared image. This is because molecular hydrogen can form on these hydrocarbons and these group together in the same way.

Stephan’s Quintet

https://www.nasa.gov/webbfirstimages — Stephan’s Quintet

Stephan’s Quintet — a dance of 4 galaxies, 300 million light years away. It is the tightest cluster of galaxies every observed.

  • The galaxy on the left is not actually even a part of the local group and is just a galaxy in the foreground only 40 million light years away.
  • Two of the galaxies are in the process of merging in this image and all four galaxies will eventually merge into one
  • This image is also the largest of the first images — a composite of 1000+ images. This means this image is made up of 150 million pixels
  • In the mid infrared version of this image. a bright spot can be seen in the centre of the top galaxy and this is a supermassive blackhole with the mass of 24 million times our sun

The Carina Nebula

https://www.nasa.gov/webbfirstimages — The Carina Nebula

This is the JWST image of the Carina Nebula, 7500 lightyears from Earth. This nebula is not the result of a supernova or dying star. Instead it’s a cloud of gas and dust actively gathering to form new stars.

  • The Carina Nebula is one of the most active sites for star formation in the Milky Way so these and similar future images can provide a lot more insight into the formation of stars in our galaxy
  • Massive young stars bombard this formation with cosmic ray, which wears away at the dense clouds of gas and like in the Southern Ring Nebula, the blue regions are hot clouds of ionized hydrogen.

As seen, these images are absolutely spectacular and offer a rich insight into the universe. These images are a bit old at this point so my apologies for the lateness! But I just wanted to give a little bit more insight into the story behind these images and I hope that the JWST provides more of these magnificent images in the future.

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