Researchers speculate that the penguin had the shape of a spiral. Today, its galactic center shines like an eye, its disordered arms now shaping as a beak, head, spine, and spread tail. The elliptical galaxy that looks like an egg was not changed by the merger process
The pair of interacting galaxies marks the second anniversary of scientific activity by the James Webb Space Telescope, which makes regular observations, including images and extremely detailed data called spectra. His activity led to a series of discoveries by astronomers around the world.
"Since United States President Joe Biden and Vice President Kamala Harris unveiled the first image from the James Webb Space Telescope two years ago, the telescope has continued to reveal the secrets of the universe," said NASA Administrator Bill Nelson. "With spectacular images from the corners of the universe, going back almost to the beginning of time, the capabilities of 'Web' shed new light on our celestial environment and inspire future generations of scientists, astronomers and explorers."
"In just two years, the Web has changed our view of the universe, enabling world-class research that has driven NASA to make this mission a reality," said Mark Clampin, director of the Astrophysics Division at NASA Headquarters in Washington.
"'Web' provides insights into enduring mysteries about the ancient universe and ushers in a new era of exploring distant worlds, bringing back images that amaze people around the world and present fascinating new questions for resolution. The telescope makes it possible to study aspects of the universe that until the beginning of its operation could not be studied."
The telescope's expertise in capturing infrared light – which is beyond what our eyes can detect – shows these galaxies, collectively known as Arp 142, caught in a slow cosmic dance. Webb's observations, which combine near and mid-infrared light from Webb's Near Infrared Camera (NIRCam) and the Medium Infrared Instrument (MIRI) respectively, clearly show that they are connected by a nebula represented in blue which is a combination of stars and gas, as a result of their mixing.
Their ongoing interaction began 25 to 75 million years ago, when the penguin (known individually as NGC 2936) and the egg (NGC 2937) completed their first transit. They will continue to twist and turn, completing several more loops before merging into one galaxy hundreds of millions of years from now.
Researchers speculate that the penguin had the shape of a spiral. Today, its galactic center shines like an eye, its disordered arms now shaping as a beak, head, spine, and spread tail.
Like all spiral galaxies, the Penguin is still very rich in gas and dust. The gravitational "dance" pulled the penguin's thinner regions of gas and dust, causing them to collide with waves and form stars. Look for these areas in two places: what looks like a fish in its beak and the "feathers" in its tail.
Surrounding these new stars is a smoke-like substance that includes carbon-containing molecules known as polycyclic aromatic hydrocarbons, which Webb excels at detecting. Dust, visible as fainter orange arcs, also flies from the beak to the tail feathers.
In contrast, the egg's compact shape remains largely unchanged. As an elliptical galaxy, it is full of aging stars and has much less gas and dust to draw from to form new stars. If both were spiral galaxies, each would end the first "twist" with the formation of new stars and a twist called tidal tails.
Another reason for the egg's unchanging appearance: these galaxies have about the same mass or gravity, which is why the apparently smaller elliptical was not swallowed or distorted by the penguin.
It is estimated that the penguin and the egg are about 100,000 light years away from each other - pretty close in astronomical terms. For the sake of comparison, the Milky Way Galaxy and the nearest galaxy to us, the Andromeda Galaxy, are about 2.5 million light years apart. They too will collide, but not in the next 4 billion years.
Now, look at the top right to see a galaxy that is not part of this event. This galaxy, called PGC 1237172, is 100 million light-years closer to Earth. It is also quite young, full of new blue stars.
Switch to Webb's mid-infrared-only image to see PGC 1237172 almost disappearing. Mid-infrared light captures mostly cool, old stars and a huge amount of dust. Because the galaxy's stellar population is so young, it "disappears" in mid-infrared light.
Also take a moment to scan the background. The image of 'Web' is full of distant galaxies. Some have spiral and oval shapes, such as those protruding through the "tail feathers" of the penguin, while others are scattered as shapeless dots. This is a testament to the sensitivity and resolution of the telescope's infrared instruments. (Compare Webb's observation to a 2018 observation that combines infrared light from NASA's Spitzer Space Telescope that has been deployed and near-infrared light and visible light from NASA's Hubble Space Telescope)
Although these observations only took a few hours, 'Webb' revealed many more distant, red and dusty galaxies than previous telescopes - one more reason to expect that 'Webb' will continue to expand our understanding of everything in the universe.
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