One of the biggest galaxy collisions ever observed is taking place at the center of this image. The four white blobs in the middle are large galaxies that have begun to tangle and ultimately merge into a single gargantuan galaxy. The whitish cloud around the colliding galaxies contains billions of stars tossed out during the messy encounter. Other galaxies and stars appear in yellow, orange and red hues. Blue shows hot gas that permeates this distant region of tightly packed galaxies. NASA's Spitzer Space Telescope spotted the four-way collision, or merger, in a giant cluster of galaxies, called CL0958+4702, located nearly five billion light-years away. The dots in the picture are a combination of galaxies in the cluster, background galaxies located behind the cluster, and foreground stars in our own Milky Way galaxy. Infrared data from Spitzer are colored red in this picture, while visible-light data from a telescope known as WIYN are green. Areas where green and red overlap appear orange or yellow. Since most galaxies in the cluster contain old stars that are visible to Spitzer and WIYN, those galaxies appear orange. Blue represents X-ray light captured by NASA's Chandra X-ray Observatory. The colliding galaxies appear white because they are in areas where all the colors overlap. The WIYN telescope, located near Tucson, Ariz., is owned and operated by the WIYN Consortium, which consists of the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatory.
Extrasolar Planet
Title
Extrasolar Planet
Description
An extrasolar planet with hypothetical (possible but unproven) water-bearing moons.
Dark Globule in IC 1396
Title
Dark Globule in IC 1396
Description
NASA's Spitzer Space Telescope image of a glowing stellar nursery provides a spectacular contrast to the opaque cloud seen in visible light. The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Located at a distance of 2,450 light-years, the globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star. The globule is being compressed by the surrounding ionized gas. The dark globule is seen in silhouette at visible-light wavelengths, backlit by the illumination of a bright star located to the left of the field of view. The Spitzer Space Telescope pierces through the obscuration to reveal the birth of new protostars, or embryonic stars, and previously unseen young stars. The infrared image, which transforms the dark cloud into a 'flying dragon,' was obtained by Spitzer's infrared array camera. The image is a four-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 filamentary appearance of the globule results from the sculpting effects of competing physical processes. The winds from a massive star, located to the left of the image, produce a dense circular rim comprising the 'head' of the globule and a swept-back tail of gas. A pair of young stars (LkHa 349 and LkHa 349c) that formed from the dense gas has cleared a spherical cavity within the globule head. While one of these stars is significantly fainter than the other in the visible-light image, they are of comparable brightness in the infrared Spitzer image. This implies the presence of a thick and dusty disc around LkHa 349c. Such circumstellar discs are the precursors of planetary systems. They are much thicker in the early stages of stellar formation when the placental planet-forming material (gas and dust) is still present.
NGC 7129
Title
NGC 7129
Description
A cluster of newborn stars herald their birth in this interstellar Valentine's Day commemorative picture obtained with NASA's Spitzer Space Telescope. These bright young stars are found in a rosebud-shaped (and rose-colored) nebulosity known as NGC 7129. The star cluster and its associated nebula are located at a distance of 3300 light-years in the constellation Cepheus. A recent census of the cluster reveals the presence of 130 young stars. The stars formed from a massive cloud of gas and dust that contains enough raw materials to create a thousand Sun-like stars. In a process that astronomers still poorly understand, fragments of this molecular cloud became so cold and dense that they collapsed into stars. Most stars in our Milky Way galaxy are thought to form in such clusters. The Spitzer Space Telescope image was obtained with an infrared array camera that is sensitive to invisible infrared light at wavelengths that are about ten times longer than visible light. In this four-color composite, emission at 3.6 microns is depicted in blue, 4.5 microns in green, 5.8 microns in orange, and 8.0 microns in red. The image covers a region that is about one quarter the size of the full moon. As in any nursery, mayhem reigns. Within the astronomically brief period of a million years, the stars have managed to blow a large, irregular bubble in the molecular cloud that once enveloped them like a cocoon. The rosy pink hue is produced by glowing dust grains on the surface of the bubble being heated by the intense light from the embedded young stars. Upon absorbing ultraviolet and visible-light photons produced by the stars, the surrounding dust grains are heated and re-emit the energy at the longer infrared wavelengths observed by Spitzer. The reddish colors trace the distribution of molecular material thought to be rich in hydrocarbons. The cold molecular cloud outside the bubble is mostly invisible in these images. However, three very young stars near the center of the image are sending jets of supersonic gas into the cloud. The impact of these jets heats molecules of carbon monoxide in the cloud, producing the intricate green nebulosity that forms the stem of the rosebud. Not all stars are formed in clusters. Away from the main nebula and its young cluster are two smaller nebulae, to the left and bottom of the central "rosebud," each containing a stellar nursery with only a few young stars. Astronomers believe that our own Sun may have formed billions of years ago in a cluster similar to NGC 7129. Once the radiation from new cluster stars destroys the surrounding placental material, the stars begin to slowly drift apart.
Dark Globule in IC 1396
Title
Dark Globule in IC 1396
Description
NASA's Spitzer Space Telescope image of a glowing stellar nursery provides a spectacular contrast to the opaque cloud seen in visible light. The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Located at a distance of 2,450 light-years, the globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star. The globule is being compressed by the surrounding ionized gas. The dark globule is seen in silhouette at visible-light wavelengths, backlit by the illumination of a bright star located to the left of the field of view. The Spitzer Space Telescope pierces through the obscuration to reveal the birth of new protostars, or embryonic stars, and previously unseen young stars. The infrared image, which transforms the dark cloud into a 'flying dragon,' was obtained by Spitzer's infrared array camera. The image is a four-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 filamentary appearance of the globule results from the sculpting effects of competing physical processes. The winds from a massive star, located to the left of the image, produce a dense circular rim comprising the 'head' of the globule and a swept-back tail of gas. A pair of young stars (LkHa 349 and LkHa 349c) that formed from the dense gas has cleared a spherical cavity within the globule head. While one of these stars is significantly fainter than the other in the visible-light image, they are of comparable brightness in the infrared Spitzer image. This implies the presence of a thick and dusty disc around LkHa 349c. Such circumstellar discs are the precursors of planetary systems. They are much thicker in the early stages of stellar formation when the placental planet-forming material (gas and dust) is still present.
A Bubble Bursts
Title
A Bubble Bursts
Description
RCW 79 is seen in the southern Milky Way, 17,200 light-years from Earth in the constellation Centaurus. The bubble is 70-light years in diameter, and probably took about one million years to form from the radiation and winds of hot young stars. The balloon of gas and dust is an example of stimulated star formation. Such stars are born when the hot bubble expands into the interstellar gas and dust around it. RCW 79 has spawned at least two groups of new stars along the edge of the large bubble. Some are visible inside the small bubble in the lower left corner. Another group of baby stars appears near the opening at the top. NASA's Spitzer Space Telescope easily detects infrared light from the dust particles in RCW 79. The young stars within RCW79 radiate ultraviolet light that excites molecules of dust within the bubble. This causes the dust grains to emit infrared light that is detected by Spitzer and seen here as the extended red features.
Dark Globule in IC 1396
Title
Dark Globule in IC 1396
Description
NASA's Spitzer Space Telescope has captured a glowing stellar nursery within a dark globule that is opaque at visible light. These new images pierce through the obscuration to reveal the birth of new protostars, or embryonic stars, and young stars never before seen. The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Located at a distance of 2,450 light-years, the globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star. The globule is being compressed by the surrounding ionized gas. The large composite image on the left is a product of combining data from the observatory's multiband imaging photometer and the infrared array camera. The thermal emission at 24 microns measured by the photometer (red) is combined with near-infrared emission from the camera at 3.6/4.5 microns (blue) and from 5.8/8.0 microns (green). The colors of the diffuse emission and filaments vary, and are a combination of molecular hydrogen (which tends to be green) and polycyclic aromatic hydrocarbon (brown) emissions. Within the globule, a half dozen newly discovered protostars are easily discernible as the bright red-tinted objects, mostly along the southern rim of the globule. These were previously undetected at visible wavelengths due to obscuration by the thick cloud ('globule body') and by dust surrounding the newly forming stars. The newborn stars form in the dense gas because of compression by the wind and radiation from a nearby massive star (located outside the field of view to the left). The winds from this unseen star are also responsible for producing the spectacular filamentary appearance of the globule itself, which resembles that of a flying dragon. The Spitzer Space Telescope also sees many newly discovered young stars, often enshrouded in dust, which may be starting the nuclear fusion that defines a star. These young stars are too cool to be seen at visible wavelengths. Both the protostars and young stars are bright in the mid-infrared because of their surrounding discs of solid material. A few of the visible-light stars in this image were found to have excess infrared emission, suggesting they are more mature stars surrounded by primordial remnants from their formation, or from crumbling asteroids and comets in their planetary systems.
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