NASA's Webb Captures Spiral Galaxies Colliding In Unprecedented Detail

NASA has released a new composite image of two spiral galaxies, NGC 2207 and IC 2163, as they begin a multi-billion-year process of merging into a single celestial entity. This event was captured with the combined power of the James Webb Space Telescope (JWST) and the Chandra X-ray Observatory.

The two galaxies, located approximately 120 million light-years away in the Canis Major constellation, actually began their slow dance roughly 40 million years ago. While the stars themselves are spaced too far apart to physically collide, the gravitational interaction is such that the larger NGC 2207 will eventually strip IC 2163 into a single galaxy. Still, the galaxies produce the equivalent of two dozen new Sun-sized stars every year. In comparison, our own Milky Way galaxy typically births only two or three such stars annually.

What makes this imagery cool is the complementary use of Chandra and JWST. From the photo above, Webb’s mid-infrared data, rendered in shades of white and red, reveals the presence of dust and the skeletal structure of the spiral arms. This dust acts as the raw material for future star systems, glowing bright as it is compressed by the forces of the neighboring galaxies. Meanwhile, Chandra’s X-ray data, shown in blue, pinpoints high-energy phenomena like supermassive black holes and the remnants of exploded stars. Both galaxies have been unusually active in recent decades, hosting seven known supernovae that have cleared out cavities in the galactic arms and further stimulated the birth of new stellar clusters.

One of the most striking features of the image is the distortion of IC 2163, the smaller of the two. As it swings counter-clockwise behind its larger partner, NGC 2207, it has been stretched into long filaments of gas and stars. These tidal extensions reach out across 100,000 light-years, appearing like eyelids or veins in the infrared spectrum. Of course, this tango is far from over. Over the next several billion years, the galaxies will continue to swing past one another, their orbits tightening until their cores eventually meld.

In a sense, this slo-mo collision serves as a preview to our own galaxy's future, as the Milky Way is on a similar collision course with the neighboring Andromeda galaxy.