Star formation as seen by Hubble and JWST.

I’m a radio astronomer specialized in star formation. Needless to say, I was excited when the new JWST observation of the Carina Nebula’s star-forming region NGC 3324 came out earlier this month. NGC 3324 is located in our galaxy, the Milky Way, roughly 7,600 light-years away from us.

Star formation is a delicate field because it takes place in regions that are covered by cosmic dust. Stars form when interstellar matter such as gas and dust swirls around to create pockets that are dense enough to collapse under their own weight. Once the collapse has started, a new star is being formed.

The Carina Nebula. A comparison between the Hubble observation from 2007 (left) and the recent JWST observation (right). Use the slider to see the image difference. Image credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) (left) and NASA, ESA, CSA, STScI (right).
Do you see the star in the top of the photos, slightly to the left? It’s almost invisible in the Hubble photo (left), but it shines clearly in the JWST photo (right). That is because a bit of dust lies in front of the star and absorbs the visible light. But because JWST observes in infrared the telescope can see right through the dust and hence photograph the star. The same effect goes for all the dark regions in the lower of the photos. They are not empty spaces, they are just full of cosmic dust. Image credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) (left) and NASA, ESA, CSA, STScI (right).

This formation process takes millions of years, but the very early stages are quick (up to 100,000 years) and difficult to capture. But once initiated the new star will continue to eat all the surrounding matter in order to grow and become large enough to fuse atoms in its core and use this energy to radiate light from the surface.

It is very difficult to see what is going on inside these collapsing pockets, because of all the surrounding space dust. Dust acts like a thick curtain to regular telescopes, so but luckily they are transparent in infrared light much like your chin is transparent to x-rays when you are at the dentist.

We therefore need a strong telescope that can pick up this infrared light from the star forming pockets, and the JWST can do exactly that, in addition to having spectacular resolution.

Dark Clouds Become Bright And Shiny

The Hubble photo above shows the star forming region in optical light compared to the JWST observation made with the NIRcam which photographs infrared light. It is very clear to see the extra detail not only arising from the increased sensitivity but also for the extra information that is simply not retrieved with the Hubble telescope.

Take a look at the dark regions on the Hubble photo. This regions are not empty or passive. They are simply opaque to Hubble’s camera and hence the telescope does not see what goes on in these pockets. But slide to the JWST photo and you see a plethora of activity in these otherwise dark and hidden regions.

These new young stars are found on the JWST photo as red dots in the dark clouds. Zoom into the high resolution image to search for these sources yourself. Below I have shown a zoomed region that exposes a tiny red dot in a dark and seemingly empty region.

Is this a new star being born? Maybe.

Zoom in on Carina Nebula.
Zoom of the JWST photo of the Carina Nebula. Young stars appear as red dots in the dark and dusty clouds of the star forming region. Details that were unavailable to us before the release of the new JWST photos. Image credit: NASA, ESA, CSA, STScI.