‘Blood-soaked’ eyes: Webb and Hubble examine galaxy pair

The gruesome palette of these galaxies is owed to a mix of mid-infrared light from the James Webb Space Telescope, and visible and ultraviolet light from the Hubble Space Telescope. Image: NASA, ESA, CSA, STScI.

Stare deeply at these galaxies. They appear as if blood is pumping through the top of a flesh-free face. The long, ghastly “stare” of their searing eye-like cores shines out into the supreme cosmic darkness.

It’s fortunate that looks can be deceiving.

These galaxies have only grazed one another to date, with the smaller spiral on the left, catalogued as IC 2163, ever so slowly “creeping” behind NGC 2207, the spiral galaxy on the right, millions of years ago.

The pair’s macabre colours represent a combination of mid-infrared light from NASA’s James Webb Space Telescope with visible and ultraviolet light from NASA’s Hubble Space Telescope.

The James Webb Space Telescope’s mid-infrared image of galaxies IC 2163 and NGC 2207 recalls the iciness of long-dead bones mixed with eerie vapors. Two large luminous “eyes” lie at the galaxies’ cores, and gauzy spiral arms reach out into the vast distances of space. Image: NASA, ESA, CSA, STScI.

Look for potential evidence of their “light scrape” in the shock fronts, where material from the galaxies may have slammed together. These lines, represented in brighter red, including the “eyelids,” may create the appearance of the galaxies’ bulging, vein-like arms.

The galaxies’ first pass may have also distorted their delicately curved arms, pulling out tidal extensions in several places. The diffuse, tiny spiral arms between IC 2163’s core and its far left arm may be an example of this activity. Even more tendrils appear to be hanging between the galaxies’ cores. Another extension “drifts” off the top of the larger galaxy, forming a thin, semi-transparent arm that practically runs off the screen.

Both galaxies have high star formation rates, like innumerable individual hearts fluttering across their arms. Each year, the galaxies produce the equivalent of two dozen new stars the size of the Sun. Our Milky Way galaxy only forms the equivalent of two or three new Sun-like stars per year. Both galaxies have also hosted seven known supernovae in recent decades, a high number compared to an average of one every 50 years in the Milky Way. Each supernova may have cleared space in their arms, rearranging gas and dust that later cooled, allowing many new stars to form.

In Hubble’s image, the star-filled spiral arms glow brightly in blue, and the galaxies’ cores in orange. Both galaxies are covered in dark brown dust lanes, which obscures the view of IC 2163’s core at left. Image: NASA, ESA, CSA, STScI

To spot the star-forming “action sequences,” look for the bright blue areas captured by Hubble in ultraviolet light, and pink and white regions detailed mainly by Webb’s mid-infrared data. Larger areas of stars are known as super star clusters. Look for examples of these in the topmost spiral arm that wraps above the larger galaxy and points to the left. Other bright regions in the galaxies are mini starbursts—locations where many stars form in quick succession. Additionally, the top and bottom “eyelid” of IC 2163, the smaller galaxy on the left, is filled with newer star formation and burns brightly.

What’s next for these spirals? Over many millions of years, the galaxies may swing by one another repeatedly. It’s possible that their cores and arms will meld, leaving behind completely reshaped arms and an even brighter, cyclops-like “eye” at the core. Star formation will also slow down once their stores of gas and dust deplete, and the scene will calm.

Source: Space Telescope Science Institute news release.