Compton Gamma Ray Observatory
The Costanzos show off their extraterrestrial quilt. CUDDLING UP IN A QUILT OF GAMMA-RAY STARS The Compton Gamma Ray Observatory is gone, but its memory lives on -- in a quilt museum located in a rural Virginia town. A retired couple in Elkwood, VA took two gamma-ray images their son received from NASA, back in 1993, and turned them into spectacular coverlets.One image, of the Crab and Geminga pulsars, is on display through September 18 at the Virginia Quilt Museum in Harrisonburg. The second, of a gamma-ray quasar called 3C 279, will have its first public viewing during a symposium on the Compton mission July 19 at NASA's Goddard Space Flight Center, Greenbelt, Md. "I can't say I know much about quilt-making, but these are fabulous reproductions of the original Compton images, right down to the smallest detail, or data point," said Dr. Neil Gehrels, a Goddard astrophysicist and project scientist for the mission. "We could use them as view graphs at meetings if the electricity should ever fail." The cosmic quilt makers are Rose and Albert Costanzo, a retired couple who manage a Christmas tree farm. In their ten years of quilting, they have never made an astronomy-themed quilt. Nor do they consider themselves amateur astronomers. Mrs. Costanzo was simply struck by the gamma-ray images that her son showed her, captured by the Energetic Gamma-Ray Experiment Telescope (EGRET), one of Compton's four instruments. Mrs. Costanzo wrote to Goddard in June after hearing about the controlled re-entry of the Compton observatory over the Pacific Ocean. "I saw in the paper that their satellite was deliberately crashed in the ocean," said Mrs. Costanzo. "I just wanted them to know that one of EGRET's many images can now be seen as a quilt hanging in a museum." Quilts have long served as a medium for astronomical images. The Bayeaux Tapestry, an embroidery measuring more than 230 feet long and 20 inches wide, depicts the appearance of Halley's Comet in 1064, which William the Conqueror saw as a sign from God that he and not Harold of England was the rightful heir of the English throne. Seven years ago, the Costanzos' son, Daniel, now a volunteer coordinator for the Albert Einstein Planetarium at the National Air and Space Museum, thought that new Compton images he had seen would lend themselves to a quilt design. Daniel Costanzo contacted Dr. Dave Thompson, a Goddard astrophysicist who works closely with EGRET data. Dr. Thompson quickly sent the family two photographs of EGRET, not knowing how they would be used. Mrs. Costanzo's letter to Dr. Thompson contained a photograph of the Crab and Geminga quilt. The EGRET team members at Goddard were so impressed that they asked the Costanzos to join them at the Compton symposium and to bring the second quilt. The Goddard Visitors Center may also display both quilts. With the success of the Compton quilts, the Costanzos plan to attempt yet another celestial image, perhaps from the Chandra X-ray Observatory. Chandra has already captured hundreds of dramatic images of supernovae and flaring stars. Rose Costanzo is a former school teacher and one of the first women to graduate from St. Bonaventure University. Albert Costanzo, a veteran of three wars, is a retired Army colonel and was a West Point classmate of Edwin "Buzz" Aldrin. The Compton Observatory, launched in 1991, re-entered the earth's atmosphere during a controlled reentry on June 4, 2000. GLAST, the Gamma-ray Large Area Space Telescope scheduled for a 2005 launch, will essentially cover the EGRET energy range with 50 times the sensitivity. Dolores Beasley Other quilt pics (and higher res pics) can be found by clicking here. (Photo credit for the high res pics goes to James Roy. For all others-- NASA/Margaret Barse.) Press Release -- "NEW CLASS OF GAMMA RAY OBJECTS DISCOVERED IN MILKY WAY" Background information on CGRO
For a jpeg copy of this image, click here. For a TIFF file of this composite image, click here. For high-res images of each image in the composite, click here. Please click on image for an low-res animation. For high-res animation, click here. BLACK HOLE GAMMA RAYS This sequence of images is taken from a computer animation illustrating how black holes in our galaxy could be a source of mysterious gamma-ray glows near the galactic plane. A black hole is an object with gravity so strong that nothing, not even light, can escape once it crosses the black hole's point of no return, called the event horizon. However, some matter can escape if it merely passes close to the event horizon without crossing it.In the first picture (top), the event horizon is the black spherical surface at the bottom. Gas (in white) is swirling around the event horizon at high speed, accelerated by the black hole's tremendous gravity. Particles in the gas collide violently with each other, releasing gamma rays, a highly energetic form of light. The second picture (middle) pulls up and away from the black hole, revealing the accretion disk in white, blue, and red, which is material spiraling into the black hole like soap suds swirling around a bathtub drain. The black hole is in the center of the accretion disk, with a jet of gas, represented by a white streak, streaming away from it toward the top of the image. When black holes swallow large amounts of matter, they are sloppy eaters, often ejecting jets of material from their poles at high speed. This process is poorly understood, but the gamma rays are produced by high speed collisions between particles in the jets. In the third picture (bottom), the observer has moved so that the line of sight is directly down one of the jets. Like looking directly into a searchlight beam, the intense gamma-rays flare brightly, outshining the accretion disk. If some black holes in our galaxy are oriented so that one of their jets is pointed directly at us, we would see it as a bright, gamma-ray glow. This is why scientists believe one possibility for the mysterious gamma-ray objects in our galaxy may be black holes with a jet pointed our way. IMAGE CREDIT: NASA/Honeywell Max Q Digital Group, Dana Berry
For a jpeg image of composite, click here For a TIFF image of composite, click here For high-res images of each image in the composite, click here. Please click on image for animation. For high-res animation, click here. NEUTRON STAR GAMMA RAYSThese images are taken from a computer animation illustrating how neutron stars in our galaxy could be a source of mysterious gamma-ray glows near the galactic plane. Neutron stars are created when a massive star explodes in a spectacularly violent event called a supernova. The core of the star collapses under its own weight while the outer layers are blown off. The core becomes the neutron star, and as it collapses, it spins much more rapidly than the original star because its diameter is a lot smaller. This is like what happens when skaters pull their outstretched arms in close to their bodies to spin faster. The collapse of the core concentrates its mass, about that of the Sun, into an extremely dense sphere the size of a large city. The collapse also concentrates the star's magnetic field; as a result, neutron stars have the most intense magnetic fields known in the Universe, up to trillions of times greater than the Earth's. In the first picture (top), the sphere in the center represents the neutron star, and the surrounding lines emerging from the top and bottom of the sphere represent its magnetic field. The whirling magnetic field produced by the neutron star's rapid rotation accelerates electrically charged particles near the star. Their acceleration generates gamma rays, represented by the blue and white beams projecting from the star's poles. In the second image (bottom), a gamma-ray beam has rotated with the star and is now pointing directly at the viewer, resulting in a bright burst of gamma-rays. Gamma-ray emitting neutron stars are one possible source, among several, for the mysterious gamma-ray glows in our galaxy. IMAGE CREDIT: NASA/Honeywell Max Q Digital Group, Dana Berry
For a jpeg image of composite, click here For a TIFF image of composite, click here For high-res images of each image in the composite, click here. To view a 125Kb movie of image above click here To view a 3.0 Mb movie click here MYSTERIOUS GAMMA-RAY OBJECTS IN OUR GALAXY This sequence of images is taken from a computer animation and an all-sky map of gamma-ray emitting objects by the Energetic Gamma Ray Telescope Experiment (EGRET) aboard NASA's Compton Gamma Ray Observatory (CGRO) spacecraft. The first two images are from the animation. The first picture (top left) represents our galaxy, the Milky Way. This viewpoint is from above the galactic plane, looking down so the spiral formations of stars, typical for galaxies like ours, can be seen. The second picture (top right) moves the viewer to our place within the galactic plane, looking toward the bright galactic center crowded with billions of stars. The horizontal band is the galactic spirals seen edge-on, and the bright area in the center represents our galactic center. The third picture (bottom left) overlays the EGRET map on the area of the galactic plane. The bright areas are the 271 gamma-ray emitting objects seen by EGRET. Since this is a map of the entire celestial sphere that has been projected on a two dimensional image, the bright objects actually surround us in the heavens. Orange and white areas along the horizon through the middle of this image are gamma-ray objects in our galactic plane. Gamma-rays are a type of highly energetic light invisible to the human eye. The false color represents intensity; large white objects glow more brightly in gamma rays than small orange ones. The fourth picture (bottom right) shows only the unidentified gamma-ray objects in our galaxy. Of the 120 unidentified sources in our galaxy, about half lie in a narrow band along the Milky Way plane. These may be well-known classes of objects that simply shine too faintly in other types of light to identify. The other half of the unidentified galactic sources are closer to Earth and make up the new class of mystery objects. These lie just off the Milky Way plane and seemingly follow the Gould Belt, a ribbon of nearby massive stars and gas clouds that winds through the Milky Way plane. What objects could be emitting gamma rays in the Gould Belt? Possibilities are black holes acting as particle accelerators, the massive stars themselves, and clusters of oddball pulsars, among other theories. IMAGE CREDIT: NASA/Honeywell Max Q Digital Group, Angela Cheyunski
For a jpeg of image, click here For a TIFF of image, click here To view a 150 Kb movie of the above image, click here To view a 2.6 Mb movie of the same, click here STELLAR WIND GAMMA RAYSThis image is taken from a computer animation illustrating how "winds" from massive stars in our galaxy could be a source of mysterious gamma-ray glows near the galactic plane. A star (red, orange and yellow sphere) ten to twenty times more massive than our Sun throws a continuous stream of electrically charged gas from its surface at high speed (diffuse orange cloud surrounding the star). This gas slams into gas atoms surrounding the star to produce gamma rays. High-speed stellar winds like there are one possible source, among several, for the mysterious gamma-ray glows in our galaxy. IMAGE CREDIT: NASA/Honeywell Max Q Digital Group, Walt Feimer NEW CLASS OF GAMMA RAY OBJECTS DISCOVERED IN MILKY WAY The exotic world of gamma-ray astronomy has taken yet another surprising turn with the revelation that half the previously unidentified high-energy gamma ray sources in our own galaxy, the Milky Way, actually comprise a new class of mysterious objects. The discovery of this new class and speculation regarding its qualities appear in the March 22 issue of Nature. "These are objects we've never seen before," said Dr. Neil Gehrels, an astrophysicist at NASA's Goddard Space Flight Center, Greenbelt, MD, and lead author on the Nature article. "We can't make out what they are yet, but we know they're strange and, boy, there's a lot of them. These are very different than the famous gamma-ray burst sources, because the gamma rays shine continuously instead of coming in a flash, like the gamma-ray bursts." The co-authors for the Nature article are Drs. Daryl Macomb, David Bertsch, David Thompson and Robert Hartman, all from Goddard. Gamma rays, although invisible to the human eye, are in fact the most powerful form of light, far more energetic than visible light, ultraviolet radiation and X-rays. The gamma rays emitted by these mystery objects are a hundred million times more powerful than visible light. The known gamma-ray universe contains 170 yet-unidentified gamma-ray sources, as listed in a 271-source catalog compiled by the Energetic Gamma Ray Telescope Experiment (EGRET) aboard NASA's Compton Gamma Ray Observatory (CGRO) spacecraft. Scientists have struggled for 20 years to associate the unidentified sources with known objects emitting other types of light. The new class reported today represents one of the first breakthroughs in their understanding. Gehrels said that of the 170 unidentified sources in our galaxy, about half lie in a narrow band along the Milky Way plane. These may be well-known classes of objects that simply shine too faintly in other types of light to be identified. The other types of light may also be obscured by intervening "fog." Gamma rays easily pass through such material. The other half of the unidentified galactic sources are closer to Earth and make up the new class. These lie just off the Milky Way plane and seemingly follow the Gould Belt, a ribbon of nearby massive stars and gas clouds that winds through the Milky Way plane. What objects could be emitting gamma rays in the Gould Belt? Possibilities are black holes acting as particle accelerators, the massive stars themselves, and clusters of oddball pulsars, among other theories. A black hole with jets of particles shooting away from it and toward us might be visible as gamma rays. Scientists have observed this phenomenon with EGRET in supermassive black holes, which lurk in the centers of distant galaxies, but never in smaller black holes within our own galaxy. For the massive-star scenario, stars 10 to 20 times as massive as the Sun could generate stellar winds that throw high- velocity particles into the surrounding space. The particles would slam into gas atoms surrounding the star to produce gamma rays. Rapidly spinning, magnetic neutron stars known as pulsars are yet another candidate for the mystery gamma-ray sources. An earlier finding by Drs. Jules Halpern (Columbia University, New York, NY), Stephen Holt (Goddard) and David Bertsch showed that the Geminga pulsar is detectable only in X-rays and gamma rays. Several of the EGRET unidentified gamma-ray sources could be exotic high-energy pulsars like this one. Such a discovery would radically change scientists' understanding of pulsar and neutron star populations, as the current census is based largely on those pulsars only detected by radio telescopes. "Once again we have come face-to-face with the knowledge that the universe is unknown to us, but has patterns that lead us to understanding," said Dr. Alan Bunner, Science Director of NASA's Structure and Evolution of the Universe program. "It's an exciting feeling." Bunner said that the unidentified gamma-ray sources will remain a tantalizing mystery until the 2005 launch of GLAST, the Gamma Ray Large Area Space Telescope. Instruments aboard GLAST will be 50 times more sensitive than the EGRET instrument. Related Links: http://www.ksc.nasa.gov/shuttle/missions/sts-37/sts-37-press-kit.txt Information about the Gamma Ray Large Area Space Telescope: GLAST people: http://www-glast.stanford.edu/people.html GLAST institutions: http://www-glast.stanford.edu/institutions.html How gamma radiation is generated in the Universe: http://imagine.gsfc.nasa.gov/docs/introduction/gamma_generation.html How gamma rays are related to other types of light: http://imagine.gsfc.nasa.gov/docs/introduction/emspectrum.html NASA's Structure and Evolution of the Universe science theme: http://universe.gsfc.nasa.gov/ Gamma ray burst information: http://imagine.gsfc.nasa.gov/docs/introduction/bursts.html NASA/GSFC Security and Privacy Statement We are interested in what you think, so please send us your comments. |
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