Posts Tagged ‘interacting galaxies’

Loops of Stars


A sparkling pink and purple loop floats in a sea of galaxies in this image from the NASA/ESA Hubble Space Telescope.

Explore this image of ring galaxy Zw II 28. What patterns or stories do you see? Leave a note in the comments below.

Galaxies come in many shapes and sizes. Some galaxies have graceful spiral arms. Some galaxies appear as disks with bulges in the center. Other galaxies, called elliptical galaxies, are just giant, milky blobs of stars. Ring galaxies, like Zw II 28, are much rarer. Although the universe seems mostly empty, galaxies do collide. Usually they pass each other and combine leaving tell-tale tails of stars and bursts of star formation. But sometimes, one galaxy will pass right through the center of another leaving behind a ring galaxy.

Interactions between galaxies stir up gas and dust. As gas and dust are pushed together, or compressed, new stars form. In Zw II 28, the outer ring is glowing with pink clouds of gas and dust and will be the home of new stars. Sparkling in these clouds, look for blue patches of light. These are brand new stars. On the right side of the ring, just inside the inner loop, look for a brighter white area. This may be a companion galaxy or perhaps even the galaxy that collided with Zw II 28 to create this rare galaxy.

As you explore the galaxy, look for the dozens of galaxies that dot the background of the image.

Zw II 28, is found about 380 million light years from Earth toward the constellation of Orion.

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A Confused Galactic V


Check out a galactic-sized “flying V in this image of interacting galaxies IC 2184 from NASA’s Hubble Space Telescope.

Explore the two nearly edge-on galaxies as they begin their billion-year-long dance. What shapes or stories do you see in the image? Leave a note in the comments below.

IC 2184 is really two galaxies. Even though space is huge, galaxies graze each other all the time. Gravity is strong with both galaxies. As the galaxies interact, stars, gas and dust are flung out into space forming long tidal tails. Look close for two faint tails. Usually these tails arc far into space but they look straight in this image because we are looking at them from the edge. The tails are arcing toward or away from us.

Also look for bright, fireworks regions. Gravity not only flings stars outward but also it can smash gas and dust. The bright blue and pink bursts are hot regions where new stars are forming, similar to regions in our galaxy such as the Orion Nebula or the Carina Nebula. These areas glow brightly enough that they show up as bright blobs of light in large telescopes.

IC 2184 is found about 160 million light-years from Earth toward the faint constellation Camelopardalis, the Giraffe.

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Floating in Hydra

Credit: NASA/ESA Hubble

An angelfish floats in the constellation of Hydra in this image of spiral galaxy NGC 4980 from the NASA/ESA Hubble Space Telescope.

Explore the curving tails of the slightly deformed shape of this spiral galaxy. What shapes or stories do you see? Leave a comment below.

Something has collided with NGC 4980. Although no galaxies are found nearby, the shape of the galaxy is slightly deformed. Distances between galaxies are huge. But every so often gravity pulls galaxies closer together. The stars themselves do not collide. Some may be thrown out of the galaxy, but most assume new orbits around the cores of their home galaxies. As the galaxies draw closer together, gas and dust clouds are pushed and pulled like taffy. New, hot blue stars blaze to life as nebulae are squeezed and compressed. This gives spiral arms in interacting galaxies a blue tinge. As we zoom into NGC 4980, look for areas of blue stars at the leading edges of the spiral arms. Look also at the center bulge. Galactic cores are usually a chaotic jumble of stars. But some galaxies like NGC 4980 keep their spiral arm structure all the way to the core. That detail makes the galaxy of interest to astronomers.

Dotting the background of this image, look for dozens of far-off galaxies. Older, cooler red stars dominate these elliptical and spiral galaxies. They are also much dimmer than NGC 4980 because they are farther away. This adds to their reddish color.

NGC 4980 lies about 80 million light-years from Earth toward the sprawling southern constellation of Hydra, the Snake.

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Arms Entangled

Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

With arms entangled, this galaxy merger resembles the letters “g” or “j” or perhaps a sea horse with a long tail arching over its head.

Explore this image of the interacting galaxy IRAS 20351 from NASA‘s Hubble Space Telescope. What pictures do you see? Leave a note below.

Dive deep into IRAS 20351+2521 and you’ll see vast dust clouds, nebulae and knots of blue stars. These patches are hot new stars born within the last million years. When galaxies interact, gas and dust are pushed and pulled together. These clouds can collapse under their own gravity and new stars can form. Sometimes scientists call these galactic collision although no stars collide. Eventually the stars that make up the two interacting galaxies will settle in new orbits around a new galactic center.

The bright stars in the image are closer stars within our own Milky Way Galaxy. IRAS 20351 is found about 450 million light-years from Earth toward the constellation Vulpecula. Vulpecula is a curious small constellation near the dense star clouds of Sagittarius. The shape of Vulpecula is the imagination of Johannes Hevelius, who created the constellation in the late 17th century. He thought it represented a “fox with the goose.” Vulpecula is the Latin word for fox.

Turtle and the Bird

Credit: NASA/JPL-Caltech/STScI/H. Inami (SSC/Caltech)

Merging galaxies form the shapes of a turtle and bird in this image from NASA‘s Hubble Space Telescope.

Explore the image of these interacting galaxies known as II Zw 096. What stories or pictures do you see? Leave a note below. I imagine a story of a bird and turtle created from a single egg. The bird, to the left, takes flight after being born while brother turtle, to the right, swims upward.

The collection of stars is really a galactic merger. Usually galaxies are very far apart. Sometimes they come close to each other. The gravity of both bring them closer and closer. In hundreds of millions of years, they will become one larger elliptical galaxy. Other examples of galactic smashups include the Antennae Galaxy and the Tadpole Galaxy.

As galaxies pass close to each other, gas and dust in the outer arms of the galaxies is pushed and pulled together like taffy. This creates a perfect environment for stars to form. A bloom of stars is taking place within this galactic merger. Astronomers call these starburst galaxies. Look at the center of the image between the two galaxies. In infrared, this region glows brightly. Infrared is a portion of the light spectrum just below what our eyes can see. We feel infrared light as heat. The heat of lots of stars being created creates the red glow we see. Thick dust blocks the visible light from this burst of new star formation.

From the nose of our bird and turtle, the galaxies span about 50,000 light years. The light from II Zw 096 is more than a half billion years old. The ancient light of these galaxies has been traveling from the direction of the constellation Delphinus, the Dolphin, for about 525 million years.


The ancient peoples saw pictures in the sky. From those patterns in the heavens, ancient storytellers created legends about heroes, maidens, dragons, bears, centaurs, dogs and mythical creatures...
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