Interacting Galaxies Captured by Webb in Stunning Detail
The interaction between the Penguin galaxy (NGC 2936) and the Egg galaxy (NGC 2937) began between 25 and 75 million years ago when they first approached each other. This cosmic dance will continue for hundreds of millions of years until the galaxies eventually merge into one.
Webb's continuous observations yield detailed images and spectra, allowing astronomers to make significant discoveries. The telescope's ability to capture infrared light, invisible to the human eye, reveals these galaxies intertwined in a slow cosmic embrace. Webb's NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) provide a composite view, highlighting a blue haze of stars and gas linking the galaxies.
Dynamic Interaction
Before their initial encounter, the Penguin galaxy exhibited a spiral structure. Now, its center gleams like an eye, with its once-spiral arms resembling a beak, head, backbone, and tail. Rich in gas and dust, the Penguin's interaction with the Egg has led to waves of star formation. New stars can be seen in regions resembling a fish in its 'beak' and the 'feathers' of its 'tail'.
These new stars are surrounded by polycyclic aromatic hydrocarbons, carbon-containing molecules that Webb excels at detecting. Dust forms faint, deep orange arcs from the Penguin's beak to its tail feathers.
In contrast, the Egg galaxy, an elliptical galaxy filled with aging stars, remains largely unchanged. With significantly less gas and dust, the Egg doesn't experience the same level of star formation as the Penguin. The similar mass of both galaxies has prevented the Penguin from consuming or significantly distorting the Egg.
Separated by approximately 100,000 light-years, the Penguin and the Egg are relatively close in astronomical terms. For comparison, the Milky Way and the Andromeda Galaxy are about 2.5 million light-years apart and will interact in about 4 billion years.
Cosmic Neighborhood
The image also features PGC 1237172, an edge-on galaxy located 100 million light-years closer to Earth, teeming with young, blue stars. In the mid-infrared image, this galaxy almost disappears, as mid-infrared light primarily captures older stars and dust. The abundance of young stars in PGC 1237172 renders it nearly invisible in this wavelength.
Webb's image is filled with distant galaxies of various shapes and sizes, showcasing the telescope's sensitivity and resolution. Compared to a 2013 Hubble Space Telescope image, Webb's observations, taken over a few hours, reveal more distant, redder, and dustier galaxies, underscoring Webb's capability to enhance our understanding of the Universe.
Arp 142 is located 326 million light-years from Earth in the Hydra constellation.
Two Years of Discoveries
In its second year, Webb has furthered its scientific goals, unveiling new information about exoplanets, star lifecycles, and the early Universe. Key discoveries include conditions for rocky planet formation, icy ingredients for new worlds, tellurium from star mergers, and detailed studies of supernova remnants SN 1987A and the Crab Nebula.
Webb has provided insights into the reionization of the Universe, hydrogen emission from galaxy mergers, and has observed the most distant black hole merger and galaxy. These observations have also highlighted the ongoing tension in Hubble constant measurements, deepening the mystery of the Universe's expansion rate.
Webb continues to deliver breathtaking images, such as the Ring Nebula, supernova remnant Cassiopeia A, and a collaborative view of the Horsehead Nebula with the Hubble and Euclid telescopes. Combining Webb and Hubble data has produced one of the most comprehensive images of the Universe, featuring galaxy cluster MACS 0416.