In the Antennae Galaxies, which are crashing into each other, giant gas clouds collided at a speed of 50 kilometers per second. It's like two trains hurtling toward each other — the impact compressed the gas, and it ignited with new stars.
Scientists aimed the ALMA radio telescope at the collision site and saw two clouds that were once a single entity. One cloud stretched into a long filament, curved like a ribbon in the wind, while the other gathered into a knot with fibers extending from it. At the junction of these structures, radio waves revealed hot gas ionized by the radiation of young stars. Nearby, the JWST infrared telescope spotted the glow of dust warmed by newborn luminaries.
Such clusters are rare guests in quiet galaxies, but in merger zones they appear one after another. Now it's clear why: cloud collisions compress gas so strongly that it transforms all at once into a dense swarm of stars. It's as if two swarms of bees flew into each other and merged into one giant hive.
The collision speed of the clouds—50 km/s — is 100 times faster than the fastest aircraft. At such an impact, the gas compresses hundreds of times, and it is this compression that triggers the birth of thousands of stars.
In Isaac Asimov's novel 'The Gods Themselves,' the collision of two universes generates energy. Here, on a smaller scale, the collision of two clouds generates the light of thousands of new stars.