galaxy collision tagged posts

An image of the colliding galaxies known as The Antennae, taken in the optical and near-infrared. Astronomers using the ALMA submillimeter array have found evidence for shocked gas near the nucleus of the northern (upper) galaxy, and argue that it is due to material infalling onto the nuclear region. Credit: ESA/Hubble & NASA

Collisions between galaxies, especially ones rich in molecular gas, can trigger bursts of star formation that heat the dust and result in their shining brightly in the infrared. Astronomers think that there is also significant gas inflowing to the central regions of galaxies that can stimulate starburst activity. Inflowing gas, as it collides with the gas in the inner regions, should produce powerful shocks that should make the gas itself glow...

Dubbed “Kathryn’s Wheel” after the famous firework it resembles and after the wife of the paper’s second author. Such systems are very rare and arise from “bulls-eye” collisions between 2 galaxies of similar mass. Shockwaves from the collision compress reservoirs of gas in each galaxy and trigger the formation of new stars. This creates a spectacular ring of intense emission, and lights up the system like a Catherine wheel firework on bonfire night.

Galaxies grow through collisions but it is rare to catch one in the process, and extremely rare to see a bull’s-eye collision in progress. Fewer than 20 systems with complete rings are known. This occurred in the constellation of Ara (the Altar).

Kathryn’s Wheel was discovered during a special wide field survey of the Southern Milky Way undert...