Compiled by astronomer Halton Arp in 1966, the catalog comprises 338 oddball interacting galaxies. But Arp didn’t collect the record just to show off galaxies that look strange. He thought these peculiar galaxies were excellent laboratories to study the physical processes that distort normal-looking elliptical and spiral galaxies.He was the first to suggest galactic encounters could form stars in bursts. His view contrasted with many astronomers during the 1960s, who wrote off misshapen galaxies as mere oddities.
They believed in a “cookie-cutter” universe that most galaxies were orderly and symmetrical. Arp believed in a different kind of universe filled with violence and birth.One such Arp galaxy that is exploding with new stars is in this Hubble Space Telescope image of the Arp 143 system. The two galaxies in this system collided Head-On, fueling the triangular-shaped burst of star formation. The pair contains the distorted, star-forming spiral galaxy NGC 2445 at the right and its less flashy companion, NGC 2444 at the left.
Astronomers suggest that the galaxies passed through each other, igniting the uniquely shaped star-formation firestorm in NGC 2445, where thousands of stars are bursting to life on the right-hand side of the image. This galaxy is awash in star birth because it is rich in gas, which makes stars. However, it hasn’t yet escaped the gravitational clutches of its partner NGC 2444, shown on the left side of the image. The pair is waging a cosmic tug-of-war, which NGC 2444 appears to be winning. The galaxy has pulled gas from NGC 2445, forming the oddball triangle of newly minted stars.