Vivid Webb Portrait of Interacting Galaxies: Penguin and Egg
The James Webb Space Telescope’s observations (which combine near- and mid-infrared light from Webb’s NIRCam [Near-InfraRed Camera] and MIRI [Mid-Infrared Instrument], respectively) clearly show that the interacting galaxies Arp 142, nicknamed the Penguin (NGC 2936) and the Egg (NGC 2937), are joined by a blue haze that is a mix of stars and gas, a result of their mingling.
Before their first approach, the Penguin held the shape of a spiral. Today, its galactic centre gleams like an eye, its unwound arms now shaping a beak, head, backbone, and fanned-out tail. Like all spiral galaxies, the Penguin is still very rich in gas and dust. The galaxies’ ‘dance’ pulled gravitationally on the Penguin’s thinner areas of gas and dust, causing them to crash in waves and form stars. Look for those areas in two places: what looks like a fish in its ‘beak’ and the ‘feathers’ in its ‘tail’.
Surrounding these newer stars is smoke-like material that includes carbon-containing molecules, known as polycyclic aromatic hydrocarbons, which Webb is exceptional at detecting. Dust, seen as fainter, deeper orange arcs also swoops from its beak to tail feathers.
In contrast, the Egg’s compact shape remains largely unchanged. As an elliptical galaxy, it is filled with ageing stars, and has a lot less gas and dust that can be pulled away to form new stars. If both were spiral galaxies, each would end the first ‘twist’ with new star formation and twirling curls, known as tidal tails.
Another reason for the Egg’s undisturbed appearance is that these galaxies have approximately the same mass, which is why the smaller-looking elliptical wasn’t consumed or distorted by the Penguin. It’s estimated that the Penguin and the Egg are about 100,000 light-years apart – quite close in astronomical terms. For context, the Milky Way galaxy and our nearest neighbor, the Andromeda Galaxy, are about 2.5 million light-years apart, about 30 times the distance. They too will interact, but not for about 4 billion years.
Over its second year of operations, the James Webb Space Telescope has advanced its science goals with a high number of groundbreaking discoveries. Astronomers have learned about the conditions under which rocky planets can form and detected the icy ingredients necessary for the formation of worlds. Webb has also shed light on the creation of tellurium during star mergers and enabled detailed studies of the supernova remnants SN 1987A and the Crab Nebula.
Peering into the distant past, Webb has solved long-standing mysteries surrounding the reionization of the Universe and the emission of hydrogen from galaxy mergers. The telescope has even captured images of the most distant black hole merger and galaxy ever observed. Furthermore, Webb’s observations have confirmed the tension between measurements of the Hubble constant, deepening the enigma surrounding the Universe’s expansion rate.
In addition to its scientific achievements, Webb has continued to produce breathtaking images of the cosmos. From the intricate beauty of the Ring Nebula to the stunning supernova remnant Cassiopeia A, the telescope has captured awe-inspiring views of celestial wonders. In a collaborative effort with the NASA/ESA Hubble Space Telescope and ESA’s Euclid telescope, Webb has also contributed to one of the most comprehensive views of the Universe ever captured, an image of the galaxy cluster MACS 0416.
Webb’s exceptional capabilities in detecting infrared light have allowed astronomers to observe previously unseen details and unveil new mysteries about the Universe. As the telescope continues its operations, it promises to further expand our understanding of the cosmos and reveal even more exciting discoveries.
