Posts Tagged ‘colliding galaxies’

Dark Banded S


A dark, warped band of dust resembling a shallow ‘S’ curls through the center of galaxy Centaurus A in this image from the European Southern Observatory.

Explore the deepest view of this active galaxy. What shapes or stories do you see? Leave a note in the comments below.

Centaurus A, also known as NGC 5128, is a massive elliptical galaxy. At its heart, lies a supermassive black hole. Scientists think only a black hole 100 million times more massive than the Sun could give off the energy we see coming from the center of this galaxy.

The most prominent feature of this galaxy is the warped lane of dust across the center of the galaxy. This is a strange structure for an elliptical galaxy. The dusty band is probably the mangled remains of another galaxy that was gobbled up by Centaurus A. This dark band contains a huge amount of dust and gas. If you zoom in close along the edges of this band, look for bright young star clusters and red-glowing clouds of hydrogen gas. As dust and gas are smashed together, new stars can form. As we move outward from the center, the elongated shape of the elliptical galaxy is seen in the glow of hundreds of billions of cooler and older stars. They glow more yellow and red than their much younger blue siblings.

In the upper left, look for the long strand of purple and pink gas. This filament is lined up with a jet of material that we cannot see with our eyes. In radio images, however, these jets are bright. More filaments can be seen farther out and toward the bottom right. Scientists think that these filaments are part of jets of material blasted from the central black hole. The closest filament is more than 30,000 light-years from the center of the galaxy. The faint outer filaments are about 65,000 light-years from galaxy’s nucleus.

Centaurus A is one of the most studied galaxies in the sky. The galaxy lies just 12 million light-years from Earth toward the constellation Centaurus. The name Centaurus A was given because it was the first major source of radio waves from that constellation in the 1950s.

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Winged Heat

Credit: ESA Herschel

Wings flank the center of Centaurus A in this far-infrared image of the elliptical galaxy from the European Space Agency’s Herschel Space Observatory and the XMM-Newton X-ray satellite.

Explore the reds, greens and blues of this giant elliptical galaxy. What shapes or stories do you see? Leave a comment below.

Centaurus A is only about 12 million light-years from Earth making it the closest giant elliptical galaxy to Earth. Scientists study the galaxy not only because it is relatively close but also because when we train our radio telescopes in its direction we are blasted with noise. Astronomers believe that a massive black hole, more than a million times heavier than our Sun, sits at the core emitting the blaring sound. In visible light, the galaxy is beautiful; a halo of stars with a dark and warped lane of dust surrounding the middle. The galaxy is bright and with a dust blocking our view of the galactic core, scientists can’t see much beyond the initial view. But by using other wavelengths of light, such as infrared or ultraviolet, astronomers can begin to see the inner workings of the galaxy.

The new images from Herschel show a flattened inner disk of a spiral galaxy. This may be the last remnants of a spiral galaxy that collided with the elliptical galaxy long ago. The dust we see across the center of the visible image is that remnant. Deeper toward the center of the galaxy, the image shows evidence of a burst of star birth. Jets shoot from the top and bottom of the galaxy curling near the top more than 15,000 light-years from the galactic core. Herschel’s sensitive telescopes pick up the warm dust surrounding the galaxy and also the searing heat as electrons are spun up to a velocity near the speed of light by the galaxy’s strong magnetic fields.

Centaurus A lies in the southern constellation of Centaurus the mythical Centaur. English astronomer Sir John Herschel first detailed the bright galaxy in the mid 19th century.

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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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