Free Astronomy Magazine September-October 2024

T his “penguin party” is loud! The distorted spiral galaxy at center, the Penguin, and the compact elliptical galaxy at left, the Egg, are locked in an active embrace. A new near- and mid-infrared image from the James Webb Space Telescope, taken to mark its second year of science, shows that their interaction is marked by a faint upside-down U-shaped blue glow. The pair, known jointly as Arp 142, made their first pass between 25 and 75 million years ago — causing “fireworks,” or new star formation, in the Penguin. In the most extreme cases, mergers can cause galaxies to form thousands of new stars per year, for a few million years. For the Penguin, research has shown that about 100 to 200 stars have formed per year. By comparison, our Milky Way galaxy (which is not interacting with a galaxy of the same size) forms roughly six to seven new stars per year. [NASA, ESA, CSA, STScI]