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Kepler Spacecraft Arrives
In a clean room at the Astro
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1/7/09
| Description |
In a clean room at the Astrotech payload processing facility in Titusville, Fla., workers prepare to rotate NASA's Kepler spacecraft before it is uncovered and prepared for initial testing. A NASA Discovery mission, Kepler is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets. After processing at Astrotech, Kepler will be transported to its launch pad at Cape Canaveral where it will be launched atop a Delta II rocket. Image credit: NASA/Chris Rhodes Jan. 6, 2009 |
| Date |
1/7/09 |
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What's up for September?
Step away from the city ligh
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9/8/08
| Title |
What's up for September? |
| Date |
9/8/08 |
| Description |
Step away from the city lights and gaze up at our Milky Way galaxy. You may even see one of the galaxy's spiral arms with your own eyes! |
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Dorian Gray
I Zwicky 18's youthful appea
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4/4/08
| Description |
I Zwicky 18's youthful appearance, resembling that of galaxies typically found only in the early universe, belies its true age. However, the Hubble telescope has found faint, older stars within this galaxy, suggesting that it formed at the same time as most other galaxies. I Zwicky 18, a dwarf irregular galaxy, is much smaller than our Milky Way Galaxy. The concentrated bluish-white knots embedded in the heart of the galaxy are two major starburst regions where stars are forming at a furious rate. The wispy blue filaments surrounding the central starburst regions are bubbles of gas that have been blown away by stellar winds and supernovae explosions from a previous generation of hot, young stars. This gas is now heated by intense ultraviolet radiation unleashed by a new generation of hot, young stars. A companion galaxy lies just above and to the left of I Zwicky 18. The companion may be interacting with I Zwicky 18 by gravitationally tugging on the galaxy. The interaction may have triggered the galaxy's recent star formation that is responsible for the youthful appearance. Besides the bluish-white young stars, white-reddish stars also are visible in both I Zwicky 18 and its companion. These stars may be as old as 10 billion years. The reddish extended objects surrounding I Zwicky 18 and its companion are ancient, fully formed galaxies of different shapes that are much farther away. Image Credit: NASA, ESA, and A. Aloisi (Space Telescope Science Institute and European Space Agency, Baltimore, Md.) |
| Date |
4/4/08 |
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The Heart of Darkness
Some of the coldest and dark
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10/5/09
| Description |
Some of the coldest and darkest dust in space shines brightly in this infrared image from the Herschel Observatory, a European Space Agency mission with important participation from NASA. The image is a composite of light captured simultaneously by two of Herschel's three instruments -- the photodetector array camera and spectrometer with its spectral and photometric imaging receiver. The image reveals a cold and turbulent region where material is just beginning to condense into new stars. It is located in the plane of our Milky Way Galaxy, 60 degrees from the center. Blue shows warmer material, red the coolest, while green represents intermediate temperatures. The red filaments are made up of the coldest material pictured here -- material that is slightly warmer than the coldest temperature theoretically attainable in the universe. Image Credit: ESA/NASA/JPL-Caltech |
| Date |
10/5/09 |
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The Birth of Stars
The spectacular new camera i
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11/10/09
| Description |
The spectacular new camera installed on NASA's Hubble Space Telescope during Servicing Mission 4 in May has delivered the most detailed view of star birth in the graceful, curving arms of the nearby spiral galaxy M83. Nicknamed the Southern Pinwheel, M83 is undergoing more rapid star formation than our own Milky Way galaxy, especially in its nucleus. The sharp 'eye' of the Wide Field Camera 3 (WFC3) has captured hundreds of young star clusters, ancient swarms of globular star clusters, and hundreds of thousands of individual stars, mostly blue supergiants and red supergiants. WFC3's broad wavelength range, from ultraviolet to near-infrared, reveals stars at different stages of evolution, allowing astronomers to dissect the galaxy's star-formation history. The image reveals in unprecedented detail the current rapid rate of star birth in this famous "grand design" spiral galaxy. The newest generations of stars are forming largely in clusters on the edges of the dark dust lanes, the backbone of the spiral arms. These fledgling stars, only a few million years old, are bursting out of their dusty cocoons and producing bubbles of reddish glowing hydrogen gas. The excavated regions give a colorful "Swiss cheese" appearance to the spiral arm. Gradually, the young stars' fierce winds (streams of charged particles) blow away the gas, revealing bright blue star clusters. These stars are about 1 million to 10 million years old. The older populations of stars are not as blue. A bar of stars, gas, and dust slicing across the core of the galaxy may be instigating most of the star birth in the galaxy's core. The bar funnels material to the galaxy's center, where the most active star formation is taking place. The brightest star clusters reside along an arc near the core. The remains of about 60 supernova blasts, the deaths of massive stars, can be seen in the image, five times more than known previously in this region. WFC3 identified the remnants of exploded stars. By studying these remnants, astronomers can better understand the nature of the progenitor stars, which are responsible for the creation and dispersal of most of the galaxy's heavy elements. M83, located in the Southern Hemisphere, is often compared to M51, dubbed the Whirlpool galaxy, in the Northern Hemisphere. Located 15 million light-years away in the constellation Hydra, M83 is two times closer to Earth than M51. Image Credit: NASA, ESA, R. O'Connell (University of Virginia), B. Whitmore (Space Telescope Science Institute), M. Dopita (Australian National University), and the Wide Field Camera 3 Science Oversight Committee |
| Date |
11/10/09 |
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Into the Heart of Darkness
Astronomers have long known
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01/06/10
| Description |
Astronomers have long known that the supermassive black hole at the center of the Milky Way Galaxy, known as Sagittarius A* (or Sgr A* for short), is a particularly poor eater. The fuel for this black hole comes from powerful winds blown off dozens of massive young stars that are concentrated nearby. These stars are located a relatively large distance away from Sgr A*, where the gravity of the black hole is weak, and so their high-velocity winds are difficult for the black hole to capture and swallow. Scientists have previously calculated that Sgr A* should consume only about 1 percent of the fuel carried in the winds. However, it now appears that Sgr A* consumes even less than expected -- ingesting only about one percent of that one percent. Why does it consume so little? The answer may be found in a new theoretical model developed using data from a very deep exposure made by NASA's Chandra X-ray Observatory. This model considers the flow of energy between two regions around the black hole: an inner region that is close to the so-called event horizon (the boundary beyond which even light cannot escape), and an outer region that includes the black hole's fuel source -- the young stars -- extending up to a million times farther out. Collisions between particles in the hot inner region transfer energy to particles in the cooler outer region via a process called conduction. This, in turn, provides additional outward pressure that makes nearly all of the gas in the outer region flow away from the black hole. The model appears to explain well the extended shape of hot gas detected around Sgr A* in X-rays as well as features seen in other wavelengths. This Chandra image of Sgr A* and the surrounding region is based on data from a series of observations lasting a total of about one million seconds, or almost two weeks. Such a deep observation has given scientists an unprecedented view of the supernova remnant near Sgr A* (known as Sgr A East) and the lobes of hot gas extending for a dozen light years on either side of the black hole. These lobes provide evidence for powerful eruptions occurring several times over the last ten thousand years. The image also contains several mysterious X-ray filaments, some of which may be huge magnetic structures interacting with streams of energetic electrons produced by rapidly spinning neutron stars. Such features are known as pulsar wind nebulas. This new model of Sgr A* was presented at the 215th meeting of the American Astronomical Society in January 2009 by Roman Shcherbakov and Robert Penna of Harvard University and Frederick K. Baganoff of the Massachusetts Institute of Technology. Image Credit: NASA/CXC/MIT/F. Baganoff, R. Shcherbakov et al. |
| Date |
01/06/10 |
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'Galactic Ghoul' Rears Its S
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| Title |
'Galactic Ghoul' Rears Its Spooky Head |
| Description |
A "monster" lurking behind a blanket of cosmic dust is unveiled in this new Halloween image from NASA's Spitzer Space Telescope. Resembling a ghoul with two hollow eyes and a screaming mouth, this masked cloud of newborn stars was uncovered by Spitzer's heat-seeking infrared eyes. The spooky cloud -- a nebula called "DR 6" residing in the plane of our Milky Way galaxy -- is home to a cluster of about 10 massive newborn stars, ranging in size from 10 to 20 times the mass of our Sun. The nebular "eyes" and "mouth" were carved out by intense heat and winds, which shoot outward from the stars (located in the central bar or "nose"). The green material remaining in the eyes and mouth is comprised of gas, while the red regions and tendrils beyond make up the dusty cloud that originally gave birth to the young stars. Within the nebula's nose, a second generation of stars is in the process of forming. These stars, in turn, will sculpt their stellar nursery, and ultimately affect the birth of yet another generation of stars. Spitzer provides astronomers with an unprecedented combination of sensitivity and spatial resolution to study this cycle in detail. DR 6 is located 3,900 light-years away in the constellation Cygnus. The distance from one end of its central bar to the other is the about 3.5 light-years, or about the same distance from our Sun to its nearest neighbor, Alpha Centauri. This image composite was taken on Nov. 27, 2003, by Spitzer's infrared array camera. It is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red). |
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Spitzer Turns Two (NGC 4725)
| Title |
Spitzer Turns Two (NGC 4725) |
| Description |
On August 25, 2003, NASA's Spitzer Space Telescope blasted into the same dark skies it now better understands. In just two years, the observatory's infrared eyes have uncovered a hidden universe teeming with warm stellar embryos, chaotic planet-forming disks, and majestic galaxies, including the delightfully odd galaxy called NGC 4725 shown here. This peculiar galaxy is thought to have only one spiral arm. Most spiral galaxies have two or more arms. Astronomers refer to NGC 4725 as a ringed barred spiral galaxy because a prominent ring of stars encircles a bar of stars at its center (the bar is seen here as a horizontal ridge with faint red features). Our own Milky Way galaxy sports multiple arms and a proportionally smaller bar and ring. In this false-color Spitzer picture, the galaxy's arm is highlighted in red, while its center and outlying halo are blue. Red represents warm dust clouds illuminated by newborn stars, while blue indicates older, cooler stellar populations. The red spokes seen projecting outward from the arm are clumps of stellar matter that may have been pushed together by instable magnetic fields. NGC 4725 is located 41 million light-years away in the constellation Coma Berenices. This picture is composed of four images taken by Spitzer's infrared array camera at 3.6 (blue), 4.5 (green), 5.8 (red), and 8.0 (red) microns. The contribution from starlight (measured at 3.6 microns) has been subtracted from the 5.8- and 8-micron images to enhance the visibility of the dust features. |
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Milky Way Bar
| Title |
Milky Way Bar |
| Description |
This artist's rendering shows a view of our own Milky Way Galaxy and its central bar as it might appear if viewed from above. An arrow indicates the location of our Sun. Astronomers have concluded for many years that our galaxy harbors a stellar bar, though its presence has been inferred indirectly. Our vantage point within the disk of the galaxy makes it difficult to accurately determine the size and shape of this bar and surrounding spiral arms. New observations by the GLIMPSE legacy team with NASA's Spitzer Space Telescope indicate that the bar-shaped collection of old stars at the center of our galaxy may be longer, and at a different orientation, than previously believed. The newly-deduced size and angle of the bar are shown relative to our Sun's location. Our Milky Way galaxy may appear to be very different from an ordinary spiral galaxy. |
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Milky Way Bar
| Title |
Milky Way Bar |
| Description |
This artist's rendering shows a view of our own Milky Way Galaxy and its central bar as it might appear if viewed from above. An arrow indicates the location of our Sun. Astronomers have concluded for many years that our galaxy harbors a stellar bar, though its presence has been inferred indirectly. Our vantage point within the disk of the galaxy makes it difficult to accurately determine the size and shape of this bar and surrounding spiral arms. New observations by the GLIMPSE legacy team with NASA's Spitzer Space Telescope indicate that the bar-shaped collection of old stars at the center of our galaxy may be longer, and at a different orientation, than previously believed. The newly-deduced size and angle of the bar are shown relative to our Sun's location. Our Milky Way galaxy may appear to be very different from an ordinary spiral galaxy. |
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A SWIRE Picture is Worth Bil
…
| Title |
A SWIRE Picture is Worth Billions of Years |
| Description |
These spectacular images, taken by the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy project, encapsulate one of the primary objectives of the Spitzer mission: to connect the evolution of galaxies from the distant, or early, universe to the nearby, or present day, universe. The larger picture (top) depicts one-tenth of the SWIRE survey field called ELAIS-N1. In this image, the bright blue sources are hot stars in our own Milky Way, which range anywhere from 3 to 60 times the mass of our Sun. The fainter green spots are cooler stars and galaxies beyond the Milky Way whose light is dominated by older stellar populations. The red dots are dusty galaxies that are undergoing intense star formation. The faintest specks of red-orange are galaxies billions of light-years away in the distant universe. The three lower panels highlight several regions of interest within the ELAIS-N1 field. The Tadpole galaxy (bottom left) is the result of a recent galactic interaction in the local universe. Although these galactic mergers are rare in the universe's recent history, astronomers believe that they were much more common in the early universe. Thus, SWIRE team members will use this detailed image of the Tadpole galaxy to help understand the nature of the "faint red-orange specks" of the early universe. The middle panel features an unusual ring-like galaxy called CGCG 275-022. The red spiral arms indicate that this galaxy is very dusty and perhaps undergoing intense star formation. The star-forming activity could have been initiated by a near head-on collision with another galaxy. The most distant galaxies that SWIRE is able to detect are revealed in a zoom of deep space (bottom right). The colors in this feature represent the same objects as those in the larger field image of ELAIS-N1. The observed SWIRE fields were chosen on the basis of being "empty" or as free as possible from the obscuring dust, gas, and stars of our own Milky Way. Because Earth is located within the Milky Way galaxy, there is always a screen of Milky Way objects blocking our view of the rest of the universe. In some places, our view of the larger universe is less obscured than others and for the most part is considered "empty." These are prime observing spots for astronomers interested in studying objects beyond the Milky Way. ELAIS-N1 is only one of six SWIRE survey fields. The full survey covers 49 square degrees of the sky, equivalent to the area covered by about 250 full moons. The SWIRE image is a 3-channel false-color composite, where blue represents visible green light (light that would appear to be blue/green to the human eye), green captures 3.6 microns, and red represents emissions at 8 microns. Interesting Note: From the Earth the SWIRE image (top image) can be seen in one square degree of sky, or a patch of sky that is approximately the size of a pea held out at arms length. |
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A SWIRE Picture is Worth Bil
…
| Title |
A SWIRE Picture is Worth Billions of Years |
| Description |
These spectacular images, taken by the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy project, encapsulate one of the primary objectives of the Spitzer mission: to connect the evolution of galaxies from the distant, or early, universe to the nearby, or present day, universe. The larger picture (top) depicts one-tenth of the SWIRE survey field called ELAIS-N1. In this image, the bright blue sources are hot stars in our own Milky Way, which range anywhere from 3 to 60 times the mass of our Sun. The fainter green spots are cooler stars and galaxies beyond the Milky Way whose light is dominated by older stellar populations. The red dots are dusty galaxies that are undergoing intense star formation. The faintest specks of red-orange are galaxies billions of light-years away in the distant universe. The three lower panels highlight several regions of interest within the ELAIS-N1 field. The Tadpole galaxy (bottom left) is the result of a recent galactic interaction in the local universe. Although these galactic mergers are rare in the universe's recent history, astronomers believe that they were much more common in the early universe. Thus, SWIRE team members will use this detailed image of the Tadpole galaxy to help understand the nature of the "faint red-orange specks" of the early universe. The middle panel features an unusual ring-like galaxy called CGCG 275-022. The red spiral arms indicate that this galaxy is very dusty and perhaps undergoing intense star formation. The star-forming activity could have been initiated by a near head-on collision with another galaxy. The most distant galaxies that SWIRE is able to detect are revealed in a zoom of deep space (bottom right). The colors in this feature represent the same objects as those in the larger field image of ELAIS-N1. The observed SWIRE fields were chosen on the basis of being "empty" or as free as possible from the obscuring dust, gas, and stars of our own Milky Way. Because Earth is located within the Milky Way galaxy, there is always a screen of Milky Way objects blocking our view of the rest of the universe. In some places, our view of the larger universe is less obscured than others and for the most part is considered "empty." These are prime observing spots for astronomers interested in studying objects beyond the Milky Way. ELAIS-N1 is only one of six SWIRE survey fields. The full survey covers 49 square degrees of the sky, equivalent to the area covered by about 250 full moons. The SWIRE image is a 3-channel false-color composite, where blue represents visible green light (light that would appear to be blue/green to the human eye), green captures 3.6 microns, and red represents emissions at 8 microns. Interesting Note: From the Earth the SWIRE image (top image) can be seen in one square degree of sky, or a patch of sky that is approximately the size of a pea held out at arms length. |
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A SWIRE Picture is Worth Bil
…
| Title |
A SWIRE Picture is Worth Billions of Years |
| Description |
These spectacular images, taken by the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy project, encapsulate one of the primary objectives of the Spitzer mission: to connect the evolution of galaxies from the distant, or early, universe to the nearby, or present day, universe. The larger picture (top) depicts one-tenth of the SWIRE survey field called ELAIS-N1. In this image, the bright blue sources are hot stars in our own Milky Way, which range anywhere from 3 to 60 times the mass of our Sun. The fainter green spots are cooler stars and galaxies beyond the Milky Way whose light is dominated by older stellar populations. The red dots are dusty galaxies that are undergoing intense star formation. The faintest specks of red-orange are galaxies billions of light-years away in the distant universe. The three lower panels highlight several regions of interest within the ELAIS-N1 field. The Tadpole galaxy (bottom left) is the result of a recent galactic interaction in the local universe. Although these galactic mergers are rare in the universe's recent history, astronomers believe that they were much more common in the early universe. Thus, SWIRE team members will use this detailed image of the Tadpole galaxy to help understand the nature of the "faint red-orange specks" of the early universe. The middle panel features an unusual ring-like galaxy called CGCG 275-022. The red spiral arms indicate that this galaxy is very dusty and perhaps undergoing intense star formation. The star-forming activity could have been initiated by a near head-on collision with another galaxy. The most distant galaxies that SWIRE is able to detect are revealed in a zoom of deep space (bottom right). The colors in this feature represent the same objects as those in the larger field image of ELAIS-N1. The observed SWIRE fields were chosen on the basis of being "empty" or as free as possible from the obscuring dust, gas, and stars of our own Milky Way. Because Earth is located within the Milky Way galaxy, there is always a screen of Milky Way objects blocking our view of the rest of the universe. In some places, our view of the larger universe is less obscured than others and for the most part is considered "empty." These are prime observing spots for astronomers interested in studying objects beyond the Milky Way. ELAIS-N1 is only one of six SWIRE survey fields. The full survey covers 49 square degrees of the sky, equivalent to the area covered by about 250 full moons. The SWIRE image is a 3-channel false-color composite, where blue represents visible green light (light that would appear to be blue/green to the human eye), green captures 3.6 microns, and red represents emissions at 8 microns. Interesting Note: From the Earth the SWIRE image (top image) can be seen in one square degree of sky, or a patch of sky that is approximately the size of a pea held out at arms length. |
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A SWIRE Picture is Worth Bil
…
| Title |
A SWIRE Picture is Worth Billions of Years |
| Description |
These spectacular images, taken by the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy project, encapsulate one of the primary objectives of the Spitzer mission: to connect the evolution of galaxies from the distant, or early, universe to the nearby, or present day, universe. The larger picture (top) depicts one-tenth of the SWIRE survey field called ELAIS-N1. In this image, the bright blue sources are hot stars in our own Milky Way, which range anywhere from 3 to 60 times the mass of our Sun. The fainter green spots are cooler stars and galaxies beyond the Milky Way whose light is dominated by older stellar populations. The red dots are dusty galaxies that are undergoing intense star formation. The faintest specks of red-orange are galaxies billions of light-years away in the distant universe. The three lower panels highlight several regions of interest within the ELAIS-N1 field. The Tadpole galaxy (bottom left) is the result of a recent galactic interaction in the local universe. Although these galactic mergers are rare in the universe's recent history, astronomers believe that they were much more common in the early universe. Thus, SWIRE team members will use this detailed image of the Tadpole galaxy to help understand the nature of the "faint red-orange specks" of the early universe. The middle panel features an unusual ring-like galaxy called CGCG 275-022. The red spiral arms indicate that this galaxy is very dusty and perhaps undergoing intense star formation. The star-forming activity could have been initiated by a near head-on collision with another galaxy. The most distant galaxies that SWIRE is able to detect are revealed in a zoom of deep space (bottom right). The colors in this feature represent the same objects as those in the larger field image of ELAIS-N1. The observed SWIRE fields were chosen on the basis of being "empty" or as free as possible from the obscuring dust, gas, and stars of our own Milky Way. Because Earth is located within the Milky Way galaxy, there is always a screen of Milky Way objects blocking our view of the rest of the universe. In some places, our view of the larger universe is less obscured than others and for the most part is considered "empty." These are prime observing spots for astronomers interested in studying objects beyond the Milky Way. ELAIS-N1 is only one of six SWIRE survey fields. The full survey covers 49 square degrees of the sky, equivalent to the area covered by about 250 full moons. The SWIRE image is a 3-channel false-color composite, where blue represents visible green light (light that would appear to be blue/green to the human eye), green captures 3.6 microns, and red represents emissions at 8 microns. Interesting Note: From the Earth the SWIRE image (top image) can be seen in one square degree of sky, or a patch of sky that is approximately the size of a pea held out at arms length. |
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A SWIRE Picture is Worth Bil
…
| Title |
A SWIRE Picture is Worth Billions of Years |
| Description |
These spectacular images, taken by the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy project, encapsulate one of the primary objectives of the Spitzer mission: to connect the evolution of galaxies from the distant, or early, universe to the nearby, or present day, universe. The larger picture (top) depicts one-tenth of the SWIRE survey field called ELAIS-N1. In this image, the bright blue sources are hot stars in our own Milky Way, which range anywhere from 3 to 60 times the mass of our Sun. The fainter green spots are cooler stars and galaxies beyond the Milky Way whose light is dominated by older stellar populations. The red dots are dusty galaxies that are undergoing intense star formation. The faintest specks of red-orange are galaxies billions of light-years away in the distant universe. The three lower panels highlight several regions of interest within the ELAIS-N1 field. The Tadpole galaxy (bottom left) is the result of a recent galactic interaction in the local universe. Although these galactic mergers are rare in the universe's recent history, astronomers believe that they were much more common in the early universe. Thus, SWIRE team members will use this detailed image of the Tadpole galaxy to help understand the nature of the "faint red-orange specks" of the early universe. The middle panel features an unusual ring-like galaxy called CGCG 275-022. The red spiral arms indicate that this galaxy is very dusty and perhaps undergoing intense star formation. The star-forming activity could have been initiated by a near head-on collision with another galaxy. The most distant galaxies that SWIRE is able to detect are revealed in a zoom of deep space (bottom right). The colors in this feature represent the same objects as those in the larger field image of ELAIS-N1. The observed SWIRE fields were chosen on the basis of being "empty" or as free as possible from the obscuring dust, gas, and stars of our own Milky Way. Because Earth is located within the Milky Way galaxy, there is always a screen of Milky Way objects blocking our view of the rest of the universe. In some places, our view of the larger universe is less obscured than others and for the most part is considered "empty." These are prime observing spots for astronomers interested in studying objects beyond the Milky Way. ELAIS-N1 is only one of six SWIRE survey fields. The full survey covers 49 square degrees of the sky, equivalent to the area covered by about 250 full moons. The SWIRE image is a 3-channel false-color composite, where blue represents visible green light (light that would appear to be blue/green to the human eye), green captures 3.6 microns, and red represents emissions at 8 microns. Interesting Note: From the Earth the SWIRE image (top image) can be seen in one square degree of sky, or a patch of sky that is approximately the size of a pea held out at arms length. |
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Cassiopeia A: Death Becomes
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| Title |
Cassiopeia A: Death Becomes Her |
| Description |
This stunning false-color picture shows off the many sides of the supernova remnant Cassiopeia A. It is made up of images taken by three of NASA's Great Observatories, using three different wavebands of light. Infrared data from the Spitzer Space Telescope are colored red, visible data from the Hubble Space Telescope are yellow, and X-ray data from the Chandra X-ray Observatory are green and blue. Located 10,000 light-years away in the northern constellation Cassiopeia, Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This remnant marks the most recent supernova in our Milky Way galaxy, and is one of the most studied objects in the sky. Each Great Observatory highlights different characteristics of this celestial orb. While Spitzer reveals warm dust in the outer shell about a few hundred degrees Kelvin (80 degrees Fahrenheit) in temperature, Hubble sees the delicate filamentary structures of hot gases about 10,000 degrees Kelvin (18,000 degrees Fahrenheit). Chandra probes unimaginably hot gases, up to about 10 million degrees Kelvin (18 million degrees Fahrenheit). These extremely hot gases were created when ejected material from Cassiopeia A smashed into surrounding gas and dust. Chandra can also see Cassiopeia A's neutron star (turquoise dot at center of shell). Blue Chandra data were acquired using broadband X-rays (low to high energies), green Chandra data correspond to intermediate energy X-rays, yellow Hubble data were taken using a 900 nanometer-wavelength filter, and red Spitzer data are from the telescope's 24-micron detector. |
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Pillars Behind the Dust
| Title |
Pillars Behind the Dust |
| Description |
The movie begins with a visible-light picture of the southern region of our Milky Way galaxy then slowly zooms into the area imaged by NASA's Spitzer Space telescope. The dust pillars are fewer and appear dark in the visible-light view because the dust is soaking up visible light. Spitzer's infrared detectors cut through this dust, allowing it to see the heat from warm, embedded star embryos, as well as deeper, more buried pillars. The false-color image taken by Spitzer shows the "South Pillar" region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope "busted open" this murky cloud to reveal star embryos (yellow or white) tucked inside finger-like pillars of thick dust (pink). Hot gases are green and foreground stars are blue. Not all of the newfound star embryos can be easily spotted. Eta Carinae is a behemoth of a star, with more than 100 times the mass of our Sun. It is so massive that it can barely hold itself together. Over the years, it has brightened and faded as material has shot away from its surface. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime. Eta Carinae's home, the Carina Nebula, is located in the southern portion of our Milky Way galaxy, 10,000 light-years from Earth. This colossal cloud of gas and dust stretches across 200 light-years of space. Though it is dominated by Eta Carinae, it also houses the star's slightly less massive siblings, in addition to the younger generations of stars. The Spitzer image was taken by the infrared array camera on the telescope. It is a three-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). The visible-light picture is from the National Optical Astronomy Observatory. |
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The (Almost) Invisible After
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| Title |
The (Almost) Invisible Aftermath of a Massive Star's Death |
| Description |
For the universe's biggest stars, even death is a show. Massive stars typically end their lives in explosive cataclysms, or supernovae, flinging abundant amounts of hot gas and radiation into outer space. Remnants of these dramatic deaths can linger for thousands of years and be easily detected by professional astronomers. However, not all stars like attention. Thirty thousand light-years away in the Cepheus constellation, astronomers think they've found a massive star whose death barely made a peep. Remnants of this shy star's supernova would have gone completely unnoticed if the super-sensitive eyes of NASA's Spitzer Space Telescope hadn't accidentally stumbled upon it. These three panels illustrate just how shy this star is. Unlike most supernova remnants, which are detectable at a variety of wavelengths ranging from radio to X-rays, this source only shows up in mid-infrared images taken by Spitzer's Multiband Imaging Photometer (MIPS). The remnant can be seen as a red-orange blob at the center of the picture. Although the visible-light (left) and near-infrared (middle) images capture the exact same region of space, the source is completely invisible in both pictures. Astronomers suspect that the remnant's elusiveness is due to its location away from our Milky Way galaxy's dusty main disk, which contains most of the galaxy's stars. A supernova is most noticeable when the material expelled during the star's furious death throes violently collides with surrounding dust. Since the shy star sits away from the galaxy's dusty and crowded disk, the hot gas and radiation it flung into space had little surrounding material to crash into. Thus, it is largely invisible at most wavelengths. MIPS did not need dust to see the remnant. The mid-infrared instrument was able to directly detect the oxygen-rich gas from the supernova's explosive death throes. The visible-light (left) image is a three-color composite of data from the California Institute of Technology's Digitized Sky Survey. In this image, light with a wavelength of 0.44 microns is represented as blue, 0.55-micron light is green, and 0.9-micron light is red. The near-infrared (middle) image is a two-color composite of data from Spitzer's infrared array camera. In this image, starlight captured at 4.5 microns is represented in blue, and 8-micron light from dust is green. The far-infrared image (right) combines the infrared array camera data with the multiband imaging photometer data, which show light of 24 microns in red. |
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The (Almost) Invisible After
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| Title |
The (Almost) Invisible Aftermath of a Massive Star's Death |
| Description |
For the universe's biggest stars, even death is a show. Massive stars typically end their lives in explosive cataclysms, or supernovae, flinging abundant amounts of hot gas and radiation into outer space. Remnants of these dramatic deaths can linger for thousands of years and be easily detected by professional astronomers. However, not all stars like attention. Thirty thousand light-years away in the Cepheus constellation, astronomers think they've found a massive star whose death barely made a peep. Remnants of this shy star's supernova would have gone completely unnoticed if the super-sensitive eyes of NASA's Spitzer Space Telescope hadn't accidentally stumbled upon it. These three panels illustrate just how shy this star is. Unlike most supernova remnants, which are detectable at a variety of wavelengths ranging from radio to X-rays, this source only shows up in mid-infrared images taken by Spitzer's Multiband Imaging Photometer (MIPS). The remnant can be seen as a red-orange blob at the center of the picture. Although the visible-light (left) and near-infrared (middle) images capture the exact same region of space, the source is completely invisible in both pictures. Astronomers suspect that the remnant's elusiveness is due to its location away from our Milky Way galaxy's dusty main disk, which contains most of the galaxy's stars. A supernova is most noticeable when the material expelled during the star's furious death throes violently collides with surrounding dust. Since the shy star sits away from the galaxy's dusty and crowded disk, the hot gas and radiation it flung into space had little surrounding material to crash into. Thus, it is largely invisible at most wavelengths. MIPS did not need dust to see the remnant. The mid-infrared instrument was able to directly detect the oxygen-rich gas from the supernova's explosive death throes. The visible-light (left) image is a three-color composite of data from the California Institute of Technology's Digitized Sky Survey. In this image, light with a wavelength of 0.44 microns is represented as blue, 0.55-micron light is green, and 0.9-micron light is red. The near-infrared (middle) image is a two-color composite of data from Spitzer's infrared array camera. In this image, starlight captured at 4.5 microns is represented in blue, and 8-micron light from dust is green. The far-infrared image (right) combines the infrared array camera data with the multiband imaging photometer data, which show light of 24 microns in red. |
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The (Almost) Invisible After
…
| Title |
The (Almost) Invisible Aftermath of a Massive Star's Death |
| Description |
For the universe's biggest stars, even death is a show. Massive stars typically end their lives in explosive cataclysms, or supernovae, flinging abundant amounts of hot gas and radiation into outer space. Remnants of these dramatic deaths can linger for thousands of years and be easily detected by professional astronomers. However, not all stars like attention. Thirty thousand light-years away in the Cepheus constellation, astronomers think they've found a massive star whose death barely made a peep. Remnants of this shy star's supernova would have gone completely unnoticed if the super-sensitive eyes of NASA's Spitzer Space Telescope hadn't accidentally stumbled upon it. These three panels illustrate just how shy this star is. Unlike most supernova remnants, which are detectable at a variety of wavelengths ranging from radio to X-rays, this source only shows up in mid-infrared images taken by Spitzer's Multiband Imaging Photometer (MIPS). The remnant can be seen as a red-orange blob at the center of the picture. Although the visible-light (left) and near-infrared (middle) images capture the exact same region of space, the source is completely invisible in both pictures. Astronomers suspect that the remnant's elusiveness is due to its location away from our Milky Way galaxy's dusty main disk, which contains most of the galaxy's stars. A supernova is most noticeable when the material expelled during the star's furious death throes violently collides with surrounding dust. Since the shy star sits away from the galaxy's dusty and crowded disk, the hot gas and radiation it flung into space had little surrounding material to crash into. Thus, it is largely invisible at most wavelengths. MIPS did not need dust to see the remnant. The mid-infrared instrument was able to directly detect the oxygen-rich gas from the supernova's explosive death throes. The visible-light (left) image is a three-color composite of data from the California Institute of Technology's Digitized Sky Survey. In this image, light with a wavelength of 0.44 microns is represented as blue, 0.55-micron light is green, and 0.9-micron light is red. The near-infrared (middle) image is a two-color composite of data from Spitzer's infrared array camera. In this image, starlight captured at 4.5 microns is represented in blue, and 8-micron light from dust is green. The far-infrared image (right) combines the infrared array camera data with the multiband imaging photometer data, which show light of 24 microns in red. |
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The (Almost) Invisible After
…
| Title |
The (Almost) Invisible Aftermath of a Massive Star's Death |
| Description |
For the universe's biggest stars, even death is a show. Massive stars typically end their lives in explosive cataclysms, or supernovae, flinging abundant amounts of hot gas and radiation into outer space. Remnants of these dramatic deaths can linger for thousands of years and be easily detected by professional astronomers. However, not all stars like attention. Thirty thousand light-years away in the Cepheus constellation, astronomers think they've found a massive star whose death barely made a peep. Remnants of this shy star's supernova would have gone completely unnoticed if the super-sensitive eyes of NASA's Spitzer Space Telescope hadn't accidentally stumbled upon it. These three panels illustrate just how shy this star is. Unlike most supernova remnants, which are detectable at a variety of wavelengths ranging from radio to X-rays, this source only shows up in mid-infrared images taken by Spitzer's Multiband Imaging Photometer (MIPS). The remnant can be seen as a red-orange blob at the center of the picture. Although the visible-light (left) and near-infrared (middle) images capture the exact same region of space, the source is completely invisible in both pictures. Astronomers suspect that the remnant's elusiveness is due to its location away from our Milky Way galaxy's dusty main disk, which contains most of the galaxy's stars. A supernova is most noticeable when the material expelled during the star's furious death throes violently collides with surrounding dust. Since the shy star sits away from the galaxy's dusty and crowded disk, the hot gas and radiation it flung into space had little surrounding material to crash into. Thus, it is largely invisible at most wavelengths. MIPS did not need dust to see the remnant. The mid-infrared instrument was able to directly detect the oxygen-rich gas from the supernova's explosive death throes. The visible-light (left) image is a three-color composite of data from the California Institute of Technology's Digitized Sky Survey. In this image, light with a wavelength of 0.44 microns is represented as blue, 0.55-micron light is green, and 0.9-micron light is red. The near-infrared (middle) image is a two-color composite of data from Spitzer's infrared array camera. In this image, starlight captured at 4.5 microns is represented in blue, and 8-micron light from dust is green. The far-infrared image (right) combines the infrared array camera data with the multiband imaging photometer data, which show light of 24 microns in red. |
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A New Star Cluster
| Title |
A New Star Cluster |
| Description |
Using an automated computer method to sift through data collected by NASA's Spitzer Space Telescope, astronomers on the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) team found a new star cluster (inset) in our Milky Way galaxy, in the northern constellation Aquila (main image). The new cluster is seen in the center of the red nebula, or star-forming cloud, as the grouping of small blue, yellow, and green stars. The wisps of red are organic molecules within the dust which have been illuminated by nearby star formation. Green indicates the presence of hot hydrogen gas. Blue predominantly reveals older stars. The bright white arc located to the lower left side of the central star cluster shows the area where a massive star is forming. For years, dense obscuring clouds of dust have blocked the central cluster from optical view. The high density of the stars triggered the GLIMPSE team's automatic cluster-finding computer program to the presence of this cluster. There are still some dust clouds even in the heart of this cluster, as seen in the inset, indicating, that stars are probably still being formed today. With time, these clouds will disappear as more stars form. The infrared image was captured with the Spitzer's infrared array camera (IRAC). The picture is a 4-channel false-color composite, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red). |
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A New Star Cluster
| Title |
A New Star Cluster |
| Description |
Using an automated computer method to sift through data collected by NASA's Spitzer Space Telescope, astronomers on the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) team found a new star cluster (inset) in our Milky Way galaxy, in the northern constellation Aquila (main image). The new cluster is seen in the center of the red nebula, or star-forming cloud, as the grouping of small blue, yellow, and green stars. The wisps of red are organic molecules within the dust which have been illuminated by nearby star formation. Green indicates the presence of hot hydrogen gas. Blue predominantly reveals older stars. The bright white arc located to the lower left side of the central star cluster shows the area where a massive star is forming. For years, dense obscuring clouds of dust have blocked the central cluster from optical view. The high density of the stars triggered the GLIMPSE team's automatic cluster-finding computer program to the presence of this cluster. There are still some dust clouds even in the heart of this cluster, as seen in the inset, indicating, that stars are probably still being formed today. With time, these clouds will disappear as more stars form. The infrared image was captured with the Spitzer's infrared array camera (IRAC). The picture is a 4-channel false-color composite, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red). |
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A New Star Cluster
| Title |
A New Star Cluster |
| Description |
Using an automated computer method to sift through data collected by NASA's Spitzer Space Telescope, astronomers on the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) team found a new star cluster (inset) in our Milky Way galaxy, in the northern constellation Aquila (main image). The new cluster is seen in the center of the red nebula, or star-forming cloud, as the grouping of small blue, yellow, and green stars. The wisps of red are organic molecules within the dust which have been illuminated by nearby star formation. Green indicates the presence of hot hydrogen gas. Blue predominantly reveals older stars. The bright white arc located to the lower left side of the central star cluster shows the area where a massive star is forming. For years, dense obscuring clouds of dust have blocked the central cluster from optical view. The high density of the stars triggered the GLIMPSE team's automatic cluster-finding computer program to the presence of this cluster. There are still some dust clouds even in the heart of this cluster, as seen in the inset, indicating, that stars are probably still being formed today. With time, these clouds will disappear as more stars form. The infrared image was captured with the Spitzer's infrared array camera (IRAC). The picture is a 4-channel false-color composite, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red). |
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All Pillars Point to Eta
| Title |
All Pillars Point to Eta |
| Description |
This false-color image taken by NASA's Spitzer Space Telescope shows the "South Pillar" region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope "busted open" this murky cloud to reveal star embryos (yellow or white) tucked inside finger-like pillars of thick dust (pink). Hot gases are green and foreground stars are blue. Not all of the newfound star embryos can be easily spotted. Though the nebula's most famous and massive star, Eta Carinae, is too bright to be observed by infrared telescopes, the downward-streaming rays hint at its presence above the picture frame. Ultraviolet radiation and stellar winds from Eta Carinae and its siblings have shredded the cloud to pieces, leaving a mess of tendrils and pillars. This shredding process triggered the birth of the new stars uncovered by Spitzer. The inset visible-light picture of the Carina Nebula shows quite a different view. Dust pillars are fewer and appear dark because the dust is soaking up visible light. Spitzer's infrared detectors cut through this dust, allowing it to see the heat from warm, embedded star embryos, as well as deeper, more buried pillars. Eta Carinae is a behemoth of a star, with more than 100 times the mass of our Sun. It is so massive that it can barely hold itself together. Over the years, it has brightened and faded as material has shot away from its surface. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime. Eta Carinae's home, the Carina Nebula, is located in the southern portion of our Milky Way galaxy, 10,000 light-years from Earth. This colossal cloud of gas and dust stretches across 200 light-years of space. Though it is dominated by Eta Carinae, it also houses the star's slightly less massive siblings, in addition to the younger generations of stars. This image was taken by the infrared array camera on Spitzer. It is a three-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). The visible-light picture is from the National Optical Astronomy Observatory. |
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All Pillars Point to Eta
| Title |
All Pillars Point to Eta |
| Description |
This false-color image taken by NASA's Spitzer Space Telescope shows the "South Pillar" region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope "busted open" this murky cloud to reveal star embryos (yellow or white) tucked inside finger-like pillars of thick dust (pink). Hot gases are green and foreground stars are blue. Not all of the newfound star embryos can be easily spotted. Though the nebula's most famous and massive star, Eta Carinae, is too bright to be observed by infrared telescopes, the downward-streaming rays hint at its presence above the picture frame. Ultraviolet radiation and stellar winds from Eta Carinae and its siblings have shredded the cloud to pieces, leaving a mess of tendrils and pillars. This shredding process triggered the birth of the new stars uncovered by Spitzer. The inset visible-light picture of the Carina Nebula shows quite a different view. Dust pillars are fewer and appear dark because the dust is soaking up visible light. Spitzer's infrared detectors cut through this dust, allowing it to see the heat from warm, embedded star embryos, as well as deeper, more buried pillars. Eta Carinae is a behemoth of a star, with more than 100 times the mass of our Sun. It is so massive that it can barely hold itself together. Over the years, it has brightened and faded as material has shot away from its surface. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime. Eta Carinae's home, the Carina Nebula, is located in the southern portion of our Milky Way galaxy, 10,000 light-years from Earth. This colossal cloud of gas and dust stretches across 200 light-years of space. Though it is dominated by Eta Carinae, it also houses the star's slightly less massive siblings, in addition to the younger generations of stars. This image was taken by the infrared array camera on Spitzer. It is a three-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). The visible-light picture is from the National Optical Astronomy Observatory. |
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All Pillars Point to Eta
| Title |
All Pillars Point to Eta |
| Description |
This false-color image taken by NASA's Spitzer Space Telescope shows the "South Pillar" region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope "busted open" this murky cloud to reveal star embryos (yellow or white) tucked inside finger-like pillars of thick dust (pink). Hot gases are green and foreground stars are blue. Not all of the newfound star embryos can be easily spotted. Though the nebula's most famous and massive star, Eta Carinae, is too bright to be observed by infrared telescopes, the downward-streaming rays hint at its presence above the picture frame. Ultraviolet radiation and stellar winds from Eta Carinae and its siblings have shredded the cloud to pieces, leaving a mess of tendrils and pillars. This shredding process triggered the birth of the new stars uncovered by Spitzer. The inset visible-light picture of the Carina Nebula shows quite a different view. Dust pillars are fewer and appear dark because the dust is soaking up visible light. Spitzer's infrared detectors cut through this dust, allowing it to see the heat from warm, embedded star embryos, as well as deeper, more buried pillars. Eta Carinae is a behemoth of a star, with more than 100 times the mass of our Sun. It is so massive that it can barely hold itself together. Over the years, it has brightened and faded as material has shot away from its surface. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime. Eta Carinae's home, the Carina Nebula, is located in the southern portion of our Milky Way galaxy, 10,000 light-years from Earth. This colossal cloud of gas and dust stretches across 200 light-years of space. Though it is dominated by Eta Carinae, it also houses the star's slightly less massive siblings, in addition to the younger generations of stars. This image was taken by the infrared array camera on Spitzer. It is a three-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). The visible-light picture is from the National Optical Astronomy Observatory. |
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Dwarf Galaxies Swimming in T
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| Title |
Dwarf Galaxies Swimming in Tidal Tails |
| Description |
This false-color infrared image from NASA's Spitzer Space Telescope shows little "dwarf galaxies" forming in the "tails" of two larger galaxies that are colliding together. The big galaxies are at the center of the picture, while the dwarfs can be seen as red dots in the red streamers, or tidal tails. The two blue dots above the big galaxies are stars in the foreground. Galaxy mergers are common occurrences in the universe, for example, our own Milky Way galaxy will eventually smash into the nearby Andromeda galaxy. When two galaxies meet, they tend to rip each other apart, leaving a trail, called a tidal tail, of gas and dust in their wake. It is out of this galactic debris that new dwarf galaxies are born. The new Spitzer picture demonstrates that these particular dwarfs are actively forming stars. The red color indicates the presence of dust produced in star-forming regions, including organic molecules called polycyclic aromatic hydrocarbons, or PAHs. PAHs are also found on Earth, in car exhaust and on burnt toast, among other places. Here, the PAHs are being heated up by the young stars, and, as a result, shine in infrared light. This image was taken by the infrared array camera on Spitzer. It is a 4-color composite of infrared light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). Starlight has been subtracted from the orange and red channels in order to enhance the dust, or PAH, features. |
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Sunset on an Alien World
| Title |
Sunset on an Alien World |
| Description |
This artist's animation illustrates what the night sky might look like from a hypothetical alien planet in a star system with an asteroid belt 25 times as massive as the one in our own solar system. NASA's Spitzer Space Telescope found evidence for such a belt around the nearby star called HD 69830, when its infrared eyes spotted dust, presumably from asteroids banging together. The telescope did not find any evidence for a planet in the system, but astronomers speculate one or more may be present. The movie begins at dusk on the imaginary world, when HD 69830, like our Sun, has begun to set over the horizon. Time is sped up to show the onset of night and the appearance of a brilliant band of light. This light comes from dust in a massive asteroid belt, which scatters sunlight. In our solar system, anybody observing the skies on a moonless night far from city lights can see this light. Called zodiacal light and sometimes the "false dawn," it appears as a faint band stretching up from the horizon when the Sun is about to rise or set. The zodiacal light in the HD 69830 system would be 1,000 times brighter than our own, outshining even the disk of our Milky Way galaxy (shown perpendicular to the asteroid-belt light). |
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Alien Asteroid Belt Compared
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| Title |
Alien Asteroid Belt Compared to our Own |
| Description |
This artist's concept illustrates what the night sky might look like from a hypothetical alien planet in a star system with an asteroid belt 25 times as massive as the one in our own solar system (alien system above, ours below). NASA's Spitzer Space Telescope found evidence for such a belt around the nearby star called HD 69830, when its infrared eyes spotted dust, presumably from asteroids banging together. The telescope did not find any evidence for a planet in the system, but astronomers speculate one or more may be present. In our solar system, anybody observing the skies on a moonless night far from city lights can see the sunlight that is scattered by dust in our asteroid belt. Called zodiacal light and sometimes the "false dawn," this light appears as a dim band stretching up from the horizon when the Sun is about to rise or set. The light is faint enough that the disk of our Milky Way galaxy remains the most prominent feature in the sky. (The Milky Way disk is shown perpendicular to the zodiacal light in both pictures.) In contrast, the zodiacal light in the HD 69830 system would be 1,000 times brighter than our own, outshining even the Milky Way. |
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Alien Asteroid Belt Compared
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| Title |
Alien Asteroid Belt Compared to our Own |
| Description |
This artist's concept illustrates what the night sky might look like from a hypothetical alien planet in a star system with an asteroid belt 25 times as massive as the one in our own solar system (alien system above, ours below). NASA's Spitzer Space Telescope found evidence for such a belt around the nearby star called HD 69830, when its infrared eyes spotted dust, presumably from asteroids banging together. The telescope did not find any evidence for a planet in the system, but astronomers speculate one or more may be present. In our solar system, anybody observing the skies on a moonless night far from city lights can see the sunlight that is scattered by dust in our asteroid belt. Called zodiacal light and sometimes the "false dawn," this light appears as a dim band stretching up from the horizon when the Sun is about to rise or set. The light is faint enough that the disk of our Milky Way galaxy remains the most prominent feature in the sky. (The Milky Way disk is shown perpendicular to the zodiacal light in both pictures.) In contrast, the zodiacal light in the HD 69830 system would be 1,000 times brighter than our own, outshining even the Milky Way. |
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Alien Asteroid Belt Compared
…
| Title |
Alien Asteroid Belt Compared to our Own |
| Description |
This artist's concept illustrates what the night sky might look like from a hypothetical alien planet in a star system with an asteroid belt 25 times as massive as the one in our own solar system (alien system above, ours below). NASA's Spitzer Space Telescope found evidence for such a belt around the nearby star called HD 69830, when its infrared eyes spotted dust, presumably from asteroids banging together. The telescope did not find any evidence for a planet in the system, but astronomers speculate one or more may be present. In our solar system, anybody observing the skies on a moonless night far from city lights can see the sunlight that is scattered by dust in our asteroid belt. Called zodiacal light and sometimes the "false dawn," this light appears as a dim band stretching up from the horizon when the Sun is about to rise or set. The light is faint enough that the disk of our Milky Way galaxy remains the most prominent feature in the sky. (The Milky Way disk is shown perpendicular to the zodiacal light in both pictures.) In contrast, the zodiacal light in the HD 69830 system would be 1,000 times brighter than our own, outshining even the Milky Way. |
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Star Clusters Found in the M
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| Title |
Star Clusters Found in the Milky Way |
| Description |
A metropolis of stellar activity is captured in these images taken by the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Legacy project. The panoramic image composite (top) captures 8 degrees of our Milky Way galaxy's plane (approximately the width of a fist held up to the sky at arm's length). The red dust clouds have been illuminated by nearby star formation, and indicate the presence of large organic molecules mixed in with the dust. The patches of black are dense, obscuring dust clouds impenetrable by even Spitzer's super-sensitive infrared eyes. Bright arcs of white throughout the image are massive stellar incubators. Tucked away in this stretch of sky are two newly discovered star clusters (bottom). These were identified using an automatic cluster-finding computer program developed by astronomers at Boston University, Mass. This software can systematically search huge areas of sky to find star groupings difficult to find by eye. The two bottom images show these very different clusters in greater detail. One is an isolated, tight grouping of older stars (left). The other shows a looser cluster situated within a wispy red ring (right). The red doughnut-shaped cloud glows from the starlight in this cluster. The many other blue dots spread across the images are older stars located at a variety of distances along this line of sight, many positioned deep in the heart of our Milky Way. The new software helps astronomers separate out these field stars from the ones within the clusters. The infrared image was captured with the Spitzer's infrared array camera (IRAC). The picture is a 4-channel false-color composite, showing emission from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). |
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A Cauldron of Stars at the G
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| Title |
A Cauldron of Stars at the Galaxy's Center |
| Description |
This dazzling infrared image from NASA's Spitzer Space Telescope shows hundreds of thousands of stars crowded into the swirling core of our spiral Milky Way galaxy. In visible-light pictures, this region cannot be seen at all because dust lying between Earth and the galactic center blocks our view. In this false-color picture, old and cool stars are blue, while dust features lit up by blazing hot, massive stars are shown in a reddish hue. Both bright and dark filamentary clouds can be seen, many of which harbor stellar nurseries. The plane of the Milky Way's flat disk is apparent as the main, horizontal band of clouds. The brightest white spot in the middle is the very center of the galaxy, which also marks the site of a supermassive black hole. The region pictured here is immense, with a horizontal span of 890 light-years and a vertical span of 640 light-years. Earth is located 26,000 light-years away, out in one of the Milky Way's spiral arms. Though most of the objects seen in this image are located at the galactic center, the features above and below the galactic plane tend to lie closer to Earth. Scientists are intrigued by the giant lobes of dust extending away from the plane of the galaxy. They believe the lobes may have been formed by winds from massive stars. This image is a mosaic of thousands of short exposures taken by Spitzer's Infrared Array Camera (IRAC), showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). The entire region was imaged in less than 16 hours. |
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A Cauldron of Stars at the G
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| Title |
A Cauldron of Stars at the Galaxy's Center |
| Description |
This dazzling infrared image from NASA's Spitzer Space Telescope shows hundreds of thousands of stars crowded into the swirling core of our spiral Milky Way galaxy. In visible-light pictures, this region cannot be seen at all because dust lying between Earth and the galactic center blocks our view. In this false-color picture, old and cool stars are blue, while dust features lit up by blazing hot, massive stars are shown in a reddish hue. Both bright and dark filamentary clouds can be seen, many of which harbor stellar nurseries. The plane of the Milky Way's flat disk is apparent as the main, horizontal band of clouds. The brightest white spot in the middle is the very center of the galaxy, which also marks the site of a supermassive black hole. The region pictured here is immense, with a horizontal span of 890 light-years and a vertical span of 640 light-years. Earth is located 26,000 light-years away, out in one of the Milky Way's spiral arms. Though most of the objects seen in this image are located at the galactic center, the features above and below the galactic plane tend to lie closer to Earth. Scientists are intrigued by the giant lobes of dust extending away from the plane of the galaxy. They believe the lobes may have been formed by winds from massive stars. This image is a mosaic of thousands of short exposures taken by Spitzer's Infrared Array Camera (IRAC), showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). The entire region was imaged in less than 16 hours. |
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A Hidden, Massive Star Clust
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| Title |
A Hidden, Massive Star Cluster Awash with Red Supergiants |
| Description |
The sky is a jewelry box full of sparkling stars in these infrared images. The crown jewels are 14 massive stars on the verge of exploding as supernovae. These hefty stars reside in one of the most massive star clusters in the Milky Way Galaxy. The bluish cluster is inside the white box in the large image, which shows the star-studded region around it. A close-up of the cluster can be seen in the inset photo. These large stars are a tip-off to the mass of the young cluster. Astronomers estimate that the cluster is at least 20,000 times as massive as the Sun. Each red supergiant is about 20 times the Sun's mass. The larger color-composite image was taken by the Spitzer Space Telescope for the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Legacy project. The survey penetrates obscuring dust along the thick disk of our galaxy to reveal never-before-seen stars and star clusters. The false colors in the image correspond to infrared-light emission. The stars in the large color-composite image all appear blue because they emit most of their infrared light at shorter wavelengths. The inset image, a false-color composite, was captured by the Two Micron All Sky Survey (2MASS). Astronomers identified the cluster as a potential behemoth after spotting it in the 2MASS catalogue. They then used the Infrared Multi-object Spectrograph at the Kitt Peak National Observatory in Arizona to analyze the cluster's colors. From that analysis, they discovered the red supergiants. They confirmed the red supergiants' pedigree by studying the colors of other red supergiants in data taken by the Spitzer Space Telescope. The cluster lies 18,900 light-years away in the direction of the constellation Scutum. It is the first in a survey of 130 potentially massive star clusters in the Milky Way that astronomers will study over the next five years using a variety of telescopes, including the Spitzer and Hubble space telescopes. The Spitzer image was taken April 4, 2004, the 2MASS image on July 4, 1999. The science team that studied the star cluster consists of Don Figer, Space Telescope Science Institute/Rochester Institute of Techology, John MacKenty, Massimo Robberto, and Kester Smith, Space Telescope Science Institute, Francisco Najarro, Instituto de Estructura de la Materia in Madrid, Spain: Rolf Kudritzki, University of Hawaii in Honolulu, and Artemio Herrero, Universidad de La Laguna in Tenerife, Spain. |
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A Hidden, Massive Star Clust
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| Title |
A Hidden, Massive Star Cluster Awash with Red Supergiants |
| Description |
The sky is a jewelry box full of sparkling stars in these infrared images. The crown jewels are 14 massive stars on the verge of exploding as supernovae. These hefty stars reside in one of the most massive star clusters in the Milky Way Galaxy. The bluish cluster is inside the white box in the large image, which shows the star-studded region around it. A close-up of the cluster can be seen in the inset photo. These large stars are a tip-off to the mass of the young cluster. Astronomers estimate that the cluster is at least 20,000 times as massive as the Sun. Each red supergiant is about 20 times the Sun's mass. The larger color-composite image was taken by the Spitzer Space Telescope for the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Legacy project. The survey penetrates obscuring dust along the thick disk of our galaxy to reveal never-before-seen stars and star clusters. The false colors in the image correspond to infrared-light emission. The stars in the large color-composite image all appear blue because they emit most of their infrared light at shorter wavelengths. The inset image, a false-color composite, was captured by the Two Micron All Sky Survey (2MASS). Astronomers identified the cluster as a potential behemoth after spotting it in the 2MASS catalogue. They then used the Infrared Multi-object Spectrograph at the Kitt Peak National Observatory in Arizona to analyze the cluster's colors. From that analysis, they discovered the red supergiants. They confirmed the red supergiants' pedigree by studying the colors of other red supergiants in data taken by the Spitzer Space Telescope. The cluster lies 18,900 light-years away in the direction of the constellation Scutum. It is the first in a survey of 130 potentially massive star clusters in the Milky Way that astronomers will study over the next five years using a variety of telescopes, including the Spitzer and Hubble space telescopes. The Spitzer image was taken April 4, 2004, the 2MASS image on July 4, 1999. The science team that studied the star cluster consists of Don Figer, Space Telescope Science Institute/Rochester Institute of Techology, John MacKenty, Massimo Robberto, and Kester Smith, Space Telescope Science Institute, Francisco Najarro, Instituto de Estructura de la Materia in Madrid, Spain: Rolf Kudritzki, University of Hawaii in Honolulu, and Artemio Herrero, Universidad de La Laguna in Tenerife, Spain. |
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A Hidden, Massive Star Clust
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| Title |
A Hidden, Massive Star Cluster Awash with Red Supergiants |
| Description |
The sky is a jewelry box full of sparkling stars in these infrared images. The crown jewels are 14 massive stars on the verge of exploding as supernovae. These hefty stars reside in one of the most massive star clusters in the Milky Way Galaxy. The bluish cluster is inside the white box in the large image, which shows the star-studded region around it. A close-up of the cluster can be seen in the inset photo. These large stars are a tip-off to the mass of the young cluster. Astronomers estimate that the cluster is at least 20,000 times as massive as the Sun. Each red supergiant is about 20 times the Sun's mass. The larger color-composite image was taken by the Spitzer Space Telescope for the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Legacy project. The survey penetrates obscuring dust along the thick disk of our galaxy to reveal never-before-seen stars and star clusters. The false colors in the image correspond to infrared-light emission. The stars in the large color-composite image all appear blue because they emit most of their infrared light at shorter wavelengths. The inset image, a false-color composite, was captured by the Two Micron All Sky Survey (2MASS). Astronomers identified the cluster as a potential behemoth after spotting it in the 2MASS catalogue. They then used the Infrared Multi-object Spectrograph at the Kitt Peak National Observatory in Arizona to analyze the cluster's colors. From that analysis, they discovered the red supergiants. They confirmed the red supergiants' pedigree by studying the colors of other red supergiants in data taken by the Spitzer Space Telescope. The cluster lies 18,900 light-years away in the direction of the constellation Scutum. It is the first in a survey of 130 potentially massive star clusters in the Milky Way that astronomers will study over the next five years using a variety of telescopes, including the Spitzer and Hubble space telescopes. The Spitzer image was taken April 4, 2004, the 2MASS image on July 4, 1999. The science team that studied the star cluster consists of Don Figer, Space Telescope Science Institute/Rochester Institute of Techology, John MacKenty, Massimo Robberto, and Kester Smith, Space Telescope Science Institute, Francisco Najarro, Instituto de Estructura de la Materia in Madrid, Spain: Rolf Kudritzki, University of Hawaii in Honolulu, and Artemio Herrero, Universidad de La Laguna in Tenerife, Spain. |
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Artist's Impression of Massi
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Artist's Impression of Massive Star Cluster |
| Description |
This is an illustration of one of the most massive star clusters within our Milky Way Galaxy. The cluster is ablaze with the glow of 14 rare red supergiant stars. Interspersed among the supergiants are young blue stars. The cluster contains an estimated 20,000 stars and is 20 times more massive than typical clusters in our galaxy. The cluster is located in the direction of the Galaxy's center. Its visible light is obscured by interstellar dust, but infrared telescopes easily detect the cluster's glow. If it could be seen in visible light, it would resemble this illustration. In this perspective we are looking back across the Milky Way, in the direction of the Sun, 18,900 light-years away. The cluster is only 8 to 10 million years old, young enough for astronomers to see most of the red supergiants before they explode as supernovae. One supernova remnant is located in the cluster at far left. In the background at the 12:00 position is a distant region of stars called W 42. |
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Seeing Stars in Serpens
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Seeing Stars in Serpens |
| Description |
Infant stars are glowing gloriously in this infrared image of the Serpens star-forming region, captured by NASA's Spitzer Space Telescope. The reddish-pink dots are baby stars deeply embedded in the cosmic cloud of gas and dust that collapsed to create it. A dusty disk of cosmic debris, or "protoplanetary disk," that may eventually form planets, surrounds the infant stars. Wisps of green throughout the image indicate the presence of carbon rich molecules called, Polycyclic Aromatic Hydrocarbons (PAHs). On Earth, PAHs can be found on charred barbecue grills and in automobile exhaust. Blue specks sprinkled throughout the image are background stars in our Milky Way Galaxy. The Serpens star-forming region is located approximately 848 light-years away in the Serpens constellation. The image is a three-channel false-color composite, where emission at 4.5 microns is blue, emission at 8.0 microns is green, and 24 micron emission is red. |
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Dusty Death of a Massive Sta
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Dusty Death of a Massive Star |
| Description |
The supernova remnant1E0102.2-7219 (inset) sits next to the nebula N76 in a bright, star-forming region of the Small Magellanic Cloud, a satellite galaxy to our Milky Way galaxy located about 200,000 light-years from Earth. A supernova remnant is made up of the messy bits and pieces of a massive star that exploded, or went supernova. The image on the right shows glowing dust grains in three wavelengths of infrared radiation: 24 microns (red) measured by the multiband imaging photometer aboard NASA's Spitzer Space Telescope, and 8.0 microns (green) and 3.6 microns (blue) measured by Spitzer's infrared array camera. The red bubble is a dust envelope around the supernova remnant E0102, which is being heated by the shock wave created in the explosion of the remnant's massive progenitor star some 1,000 years ago. Most of the blue stars are in the Small Magellanic Cloud, though some are in our own galaxy. The close-up of E0102 on the left is a composite of the infrared observations by Spitzer (red), an optical image (0.5 microns) captured by NASA's Hubble Space Telescope (green), and X-ray measurements by NASA's Chandra X-ray Observatory (blue). The X-ray ring is generated when the reverse shock slams into stellar material that was expelled during the explosion. |
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Dusty Death of a Massive Sta
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| Title |
Dusty Death of a Massive Star |
| Description |
The supernova remnant1E0102.2-7219 (inset) sits next to the nebula N76 in a bright, star-forming region of the Small Magellanic Cloud, a satellite galaxy to our Milky Way galaxy located about 200,000 light-years from Earth. A supernova remnant is made up of the messy bits and pieces of a massive star that exploded, or went supernova. The image on the right shows glowing dust grains in three wavelengths of infrared radiation: 24 microns (red) measured by the multiband imaging photometer aboard NASA's Spitzer Space Telescope, and 8.0 microns (green) and 3.6 microns (blue) measured by Spitzer's infrared array camera. The red bubble is a dust envelope around the supernova remnant E0102, which is being heated by the shock wave created in the explosion of the remnant's massive progenitor star some 1,000 years ago. Most of the blue stars are in the Small Magellanic Cloud, though some are in our own galaxy. The close-up of E0102 on the left is a composite of the infrared observations by Spitzer (red), an optical image (0.5 microns) captured by NASA's Hubble Space Telescope (green), and X-ray measurements by NASA's Chandra X-ray Observatory (blue). The X-ray ring is generated when the reverse shock slams into stellar material that was expelled during the explosion. |
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Dusty Death of a Massive Sta
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| Title |
Dusty Death of a Massive Star |
| Description |
The supernova remnant1E0102.2-7219 (inset) sits next to the nebula N76 in a bright, star-forming region of the Small Magellanic Cloud, a satellite galaxy to our Milky Way galaxy located about 200,000 light-years from Earth. A supernova remnant is made up of the messy bits and pieces of a massive star that exploded, or went supernova. The image on the right shows glowing dust grains in three wavelengths of infrared radiation: 24 microns (red) measured by the multiband imaging photometer aboard NASA's Spitzer Space Telescope, and 8.0 microns (green) and 3.6 microns (blue) measured by Spitzer's infrared array camera. The red bubble is a dust envelope around the supernova remnant E0102, which is being heated by the shock wave created in the explosion of the remnant's massive progenitor star some 1,000 years ago. Most of the blue stars are in the Small Magellanic Cloud, though some are in our own galaxy. The close-up of E0102 on the left is a composite of the infrared observations by Spitzer (red), an optical image (0.5 microns) captured by NASA's Hubble Space Telescope (green), and X-ray measurements by NASA's Chandra X-ray Observatory (blue). The X-ray ring is generated when the reverse shock slams into stellar material that was expelled during the explosion. |
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Amazing Andromeda Galaxy
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Amazing Andromeda Galaxy |
| Description |
The many "personalities" of our great galactic neighbor, the Andromeda galaxy, are exposed in this new composite image from NASA's Galaxy Evolution Explorer and the Spitzer Space Telescope. The wide, ultraviolet eyes of Galaxy Evolution Explorer reveal Andromeda's "fiery" nature -- hotter regions brimming with young and old stars. In contrast, Spitzer's super-sensitive infrared eyes show Andromeda's relatively "cool" side, which includes embryonic stars hidden in their dusty cocoons. Galaxy Evolution Explorer detected young, hot, high-mass stars, which are represented in blue, while populations of relatively older stars are shown as green dots. The bright yellow spot at the galaxy's center depicts a particularly dense population of old stars. Swaths of red in the galaxy's disk indicate areas where Spitzer found cool, dusty regions where stars are forming. These stars are still shrouded by the cosmic clouds of dust and gas that collapsed to form them. Together, Galaxy Evolution Explorer and Spitzer complete the picture of Andromeda's swirling spiral arms. Hints of pinkish purple depict regions where the galaxy's populations of hot, high-mass stars and cooler, dust-enshrouded stars co-exist. Located 2.5 million light-years away, the Andromeda is our largest nearby galactic neighbor. The galaxy's entire disk spans about 260,000 light-years, which means that a light beam would take 260,000 years to travel from one end of the galaxy to the other. By comparison, our Milky Way galaxy's disk is about 100,000 light-years across. This image is a false color composite comprised of data from Galaxy Evolution Explorer's far-ultraviolet detector (blue), near-ultraviolet detector (green), and Spitzer's multiband imaging photometer at 24 microns (red). |
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A Shocking Surprise in Steph
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A Shocking Surprise in Stephan's Quintet |
| Description |
This false-color composite image of the Stephan's Quintet galaxy cluster clearly shows one of the largest shock waves ever seen (green arc), produced by one galaxy falling toward another at over a million miles per hour. It is made up of data from NASA's Spitzer Space Telescope and a ground-based telescope in Spain. Four of the five galaxies in this image are involved in a violent collision, which has already stripped most of the hydrogen gas from the interiors of the galaxies. The centers of the galaxies appear as bright yellow-pink knots inside a blue haze of stars, and the galaxy producing all the turmoil, NGC7318b, is the left of two small bright regions in the middle right of the image. One galaxy, the large spiral at the bottom left of the image, is a foreground object and is not associated with the cluster. The titanic shock wave, larger than our own Milky Way galaxy, was detected by the ground-based telescope using visible-light wavelengths. It consists of hot hydrogen gas. As NGC7318b collides with gas spread throughout the cluster, atoms of hydrogen are heated in the shock wave, producing the green glow. Spitzer pointed its infrared spectrograph at the peak of this shock wave (middle of green glow) to learn more about its inner workings. This instrument breaks light apart into its basic components. Data from the instrument are referred to as spectra and are displayed as curving lines that indicate the amount of light coming at each specific wavelength. The Spitzer spectrum showed a strong infrared signature for incredibly turbulent gas made up of hydrogen molecules. This gas is caused when atoms of hydrogen rapidly pair-up to form molecules in the wake of the shock wave. Molecular hydrogen, unlike atomic hydrogen, gives off most of its energy through vibrations that emit in the infrared. This highly disturbed gas is the most turbulent molecular hydrogen ever seen. Astronomers were surprised not only by the turbulence of the gas, but by the incredible strength of the emission. The reason the molecular hydrogen emission is so powerful is not yet completely understood. Stephan's Quintet is located 300 million light-years away in the Pegasus constellation. This image is composed of three data sets: near-infrared light (blue) and visible light called H-alpha (green) from the Calar Alto Observatory in Spain, operated by the Max Planck Institute in Germany, and 8-micron infrared light (red) from Spitzer's infrared array camera. |
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Black Hole Spills Kaleidosco
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Black Hole Spills Kaleidoscope of Color |
| Description |
This new false-colored image from NASA's Hubble, Chandra and Spitzer space telescopes shows a giant jet of particles that has been shot out from the vicinity of a type of supermassive black hole called a quasar. The jet is enormous, stretching across more than 100,000 light-years of space ? a size comparable to our own Milky Way galaxy! Quasars are among the brightest objects in the universe. They consist of supermassive black holes surrounded by turbulent material, which is being heated up as it is dragged toward the black hole. This hot material glows brilliantly, and some of it gets blown off into space in the form of powerful jets. The jet pictured here is streaming out from the first known quasar, called 3C273, discovered in 1963. A kaleidoscope of colors represents the jet's assorted light waves. X-rays, the highest-energy light in the image, are shown at the far left in blue (the black hole itself is well to the left of the image). The X-rays were captured by Chandra. As you move from left to right, the light diminishes in energy, and wavelengths increase in size. Visible light recorded by Hubble is displayed in green, while infrared light caught by Spitzer is red. Areas where visible and infrared light overlap appear yellow. |
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Rings Around the Galaxy
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Rings Around the Galaxy |
| Description |
Three newly-discovered streams arcing high over the Milky Way Galaxy are remnants of cannibalized galaxies and star clusters. The streams are between 13,000 and 130,000 light-years distant from Earth and extend over much of the northern sky. Two of the newly discovered streams are almost certainly the remains of ancient star clusters. Known to astronomers as globular clusters, these giant stellar cities contain between tens of thousands and millions of stars. Though only about 150 globular clusters orbit the Milky Way today, they may once have numbered in the thousands. Over billions of years, the relentless gravitational stresses inflicted on them by our galaxy have slowly torn them apart, leaving behind long, thin streams of stars. Once crowded so closely together that they could sometimes actually collide, these stars are now separated by many light-years, trailing one another at half a million miles an hour through the dark and lonely reaches of the galactic halo. The third stream is spread over a much larger region of the sky, and is most likely the scattered remains of a dwarf galaxy. Such dwarf galaxies may contain up to 100 million stars, along with sometimes substantial amounts of mysterious "dark matter." While the Milky Way galaxy currently hosts a family of 20 or so known dwarf galaxies, scientists who study the growth of galaxies in the early universe have long been puzzled as to why we don't see hundreds of them. |
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Rings Around the Galaxy
| Title |
Rings Around the Galaxy |
| Description |
Three newly-discovered streams arcing high over the Milky Way Galaxy are remnants of cannibalized galaxies and star clusters. The streams are between 13,000 and 130,000 light-years distant from Earth and extend over much of the northern sky. Two of the newly discovered streams are almost certainly the remains of ancient star clusters. Known to astronomers as globular clusters, these giant stellar cities contain between tens of thousands and millions of stars. Though only about 150 globular clusters orbit the Milky Way today, they may once have numbered in the thousands. Over billions of years, the relentless gravitational stresses inflicted on them by our galaxy have slowly torn them apart, leaving behind long, thin streams of stars. Once crowded so closely together that they could sometimes actually collide, these stars are now separated by many light-years, trailing one another at half a million miles an hour through the dark and lonely reaches of the galactic halo. The third stream is spread over a much larger region of the sky, and is most likely the scattered remains of a dwarf galaxy. Such dwarf galaxies may contain up to 100 million stars, along with sometimes substantial amounts of mysterious "dark matter." While the Milky Way galaxy currently hosts a family of 20 or so known dwarf galaxies, scientists who study the growth of galaxies in the early universe have long been puzzled as to why we don't see hundreds of them. |
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Infrared View of Spitzer
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Infrared View of Spitzer |
| Description |
Spitzer seen against the infrared sky. The band of light is the glowing dust emission from the Milky Way galaxy seen at 100 microns (as seen by the IRAS/COBE missions). The cloud complexes around Orion and the disk of the Milky Way are seen behind the observatory. |
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Andromeda Makes a Splash
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Andromeda Makes a Splash |
| Description |
This infrared composite image from NASA's Spitzer Space Telescope shows the Andromeda galaxy, a neighbor to our Milky Way galaxy. The main image (top) highlights the contrast between the galaxy's choppy waves of dust (red) and smooth sea of older stars (blue). The panels below the main image show the galaxy's older stars (left) and dust (right) separately. Spiral galaxies tend to form new stars in their dusty, clumpy arms, while their cores are populated by older stars. The Spitzer view also shows Andromeda's dust lanes twisting all the way into the center of the galaxy, a region that is crammed full of stars. In visible-light pictures, this central region tends to be dominated by starlight. Astronomers used these new images to measure the total infrared brightness of Andromeda. Because the amount of infrared light given off by stars depends on their masses, the brightness measurements provided a novel method for "weighing" the Andromeda galaxy. According to this method, the mass of the stars in Andromeda is about110 billion times that of the sun, which is in agreement with past calculations. This means the galaxy contains about one trillion stars (because most stars are actually less massive than the sun). For comparison, the Milky Way is estimated to hold about 400 billion stars. A small, companion galaxy called NGC 205 is visible above Andromeda. Another companion galaxy called M32 can also been seen below the galaxy. The Andromeda galaxy, also known affectionately by astronomers as Messier 31, is located 2.5 million light-years away in the constellation Andromeda. It is the closest major galaxy to the Milky Way, making it the ideal specimen for carefully examining the nature of galaxies. On a clear, dark night, the galaxy can be spotted with the naked eye as a fuzzy blob. Andromeda's entire disk spans about 260,000 light-years, which means that a light beam would take 260,000 years to travel from one end of the galaxy to the other. By comparison, the Milky Way is about 100,000 light-years across. When viewed from Earth, Andromeda occupies a portion of the sky equivalent to seven full moons. Because this galaxy is so large, the infrared images had to be stitched together out of about 3,000 separate Spitzer exposures. The light detected by Spitzer's infrared array camera at 3.6 and 4.5 microns is sensitive mostly to starlight and is shown in blue and green, respectively. The 8-micron light shows warm dust and is shown in red. The contribution from starlight has been subtracted from the 8-micron image to better highlight the dust structures. |
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