From the January 2024 issue

UGC 12914 and UGC 12915

By | Published: January 1, 2024

A long time ago, two spiral galaxies far, far away were slowly drawing closer to each other, until, about 25 million to 30 million years before the image here was taken, they collided head-on.

Found 180 million light-years away in the constellation Pegasus, both UGC 12914 and UGC 12915 managed to pull away from each other but were left badly warped and stretched from this violent event. The aftermath shows a bridge of hydrogen gas connecting the two. In radio images, it makes the galaxies look like warm taffy candy being pulled apart. That, plus their twisted appearances, led to the nickname the Taffy Galaxies.

There was so much momentum that each galaxy kept moving despite the crash — a case of a galactic hit-and-run. Such collisions often trigger rapid bursts of star formation, but for this pair the opposite happened. The cosmic dust and glowing red clouds of ionized hydrogen between the galaxies have all the necessary materials for new stars to be born. However, due to the head-on nature of the collision, the impact between galactic disks and gases injected a massive amount of energy, creating fierce turbulence. This chaos hindered the collection and compression of gas necessary for new star formation.