Interacting galaxies Arp 142 (Hubble and Webb image)

This image shows two views of Arp 142 (nicknamed the Penguin and the Egg). The image on the left from the NASA/ESA Hubble Space Telescope shows the target in 2013. On the right is the NASA/ESA/CSA James Webb Space Telescope’s view of the same region in near-infrared light with the NIRCam instrument.

Both images are made up of several filters. The process of applying colour to Webb’s images is remarkably similar to the approach used for Hubble: the shortest wavelengths are assigned blue and the longest wavelengths are assigned red. For Webb, image processors translate near-infrared light images, in order, to visible colours. Both telescopes take high-resolution images, so there are many features to explore.

In Hubble’s visible light image, a dark brown dust lane begins across the Penguin’s ‘beak’ and extends through its body and along its back. In Webb’s near-infrared view, this dust lane is significantly fainter.

Linger on Webb’s image. A faint upside-down U shape joins the pair of galaxies. This is a combination of stars, gas, and dust that continues to mix as the galaxies mingle. In Hubble’s view, notice there is a clearer gap between the Penguin’s ‘beak’ and the top of the Egg. Toward the bottom of the Penguin’s tail are several prominent spiral galaxies, though there are a few more in Webb’s image.

The Egg itself looks similar in both images, but in Webb’s view, the galaxy shines so brightly that it causes diffraction spikes to slightly extend its gleam. The galaxy at top right appears about the same size, but many more pinpricks of stars appear in Webb’s view.

Now compare the backgrounds. Hubble shows many distant galaxies in visible light, though areas in the corners that are completely black were outside the telescope’s field of view. Many more distant galaxies gleam in Webb’s infrared image. This is a testament to the sensitivity and resolution of Webb’s near-infrared camera, and the advantages of infrared light. Light from distant galaxies is stretched as it travels across the Universe, so a significant portion of their light can only be detected at longer wavelengths. 

Explore Webb’s near- and mid-infrared light image and its mid-infrared light-only image.

[Image description: Frame is split down the middle: Hubble’s visible light image at left, and Webb’s near-infrared image at right. Both show the Egg at left and the Penguin at right.]

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