A YEAR IN REVIEW:
SAGITTARIUS A*: MILKY WAY MONSTER STARS IN COSMIC REALITY SHOW - The longest X-ray look yet at the supermassive black hole at the Milky Way's center has given astronomers unprecedented access to its life and times. The new data from NASA's Chandra X-ray Observatory revealed that our galaxy's central black hole is a frequent bad actor, prone to numerous outbursts and occasional large explosions. This Chandra image of the supermassive black hole at our Galaxy's center, a.k.a. Sagittarius A* or Sgr A*, was made from the longest X-ray exposure of that region to date. In addition to Sgr A* more than two thousand other X-ray sources were detected in the region, making this one of the richest fields ever observed.
ITEM (1): Sequence of Chandra Images of Galactic Center & Sgr A* - This sequence begins with a 400 by 900 light-year mosaic of several Chandra images of the central region of our Galaxy that reveals hundreds of white dwarf stars, neutron stars, and black holes bathed in an incandescent fog of multimillion-degree gas. The mosaic then zooms into a large region around the supermassive black hole at our Galaxy's center, a.k.a. Sagittarius A* or Sgr A*. Marked in this field around Sgr A* are two newly discovered large lobes of multimillion-degree gas that extend for dozens of light years on either side of the black hole. The final Chandra image in this sequence is a close-up of the location of the supermassive black hole Sgr A* and an X-ray jet. This suspected jet is 1.5 light years in length and is due to high-energy particles ejected from the vicinity of the black hole. Courtesy: NASA/Chandra X-ray Observatory
ITEM (2): Black Hole Flare Animation - This sequence begins with a 600,000-second exposure of Sgr A* made with NASA's Chandra X-ray Observatory. Next, it zooms into the precise location of the central supermassive hole, and then dissolves into an artist's rendition of the system. This illustrates how high-energy particles and X-ray flares are produced when matter falls onto the accretion disk around a supermassive black hole. This animation illustrates an eruption that produces high-energy particles and an X-ray flare from the central region of an accretion disk around a super massive black hole.Courtesy: NASA/Chandra X-ray Observatory
[MSFC News Release #03-002 (1/6/03)
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WMAP CAPTURES IMAGE OF INFANT UNIVERSE "BABY PICTURE" REVEALS AGE OF UNIVERSE AND RECIPE OF THE COSMOS (G03-015) - With a sweeping 12-month observation of the entire sky, scientists using NASA's Wilkinson Microwave Anisotropy Probe (WMAP) have created the most detailed portrait ever of the infant Universe, revealing its age and other key characteristics. This new portrait -- capturing the afterglow of the Big Bang, called the cosmic microwave background (CMB) -- pegs the age of the Universe at 13.7 billion years old. Encoded in these patterns is the much-anticipated information about the fundamental properties of the early Universe, including the era when stars first ignited.
SECTION 1: A Cosmic "Baby Picture" of The Universe
The Wilkinson Microwave Anisotropy Probe (WMAP) Full-Sky Map
a) WMAP - Capturing the First and Oldest Light in the Universe- This is a picture of the earliest light in the Universe. The new, unprecedented full-sky picture brings into focus infinitesimal patterns that mark the seeds of what later grew into the clusters of galaxies we see today. Encoded in these patterns is the much-anticipated information about the fundamental properties of the early Universe, including the era when stars first ignited. This era is only 200 million years after the Big Bang, much earlier than many scientists thought.
b) WMAP - Close-up - Detailed version of the Wilkinson Microwave Anisotropy Probe (WMAP) Full-Sky Map. Courtesy: NASA
SECTION 2: Science Results
a) Evolution - Version 1 - Zooming in on the new portrait of the infant Universe reveals how stars and galaxies formed and evolved into the vast structure we see today. Temperature fluctuations seen today in the CMB reflect density fluctuations moments after the Big Bang. Areas of slightly enhanced density had stronger gravity than low-density areas. The gravity from high-density areas "pulled back" on the background radiation, making it appear slightly cooler in those directions. This animation depicts how matter, dictated by gravity, falls into regions of higher density -- creating filaments of gas built upon unseen, underlying dark matter. As gas condensed, stars began to form. Next, a more hierarchical structure evolved, with chains of galaxies crisscrossing to form galaxy clusters and superclusters. We pan out to reveal a look back in time, from modern day to early star and galaxy formation, to the microwave background and the beginning of time.
b) Evolution - Version 2
c) Fingerprints - Theories about the evolution of the Universe make specific predictions about the extent of temperature fluctuations in the Cosmic Microwave Background, a pattern frozen into place 380,000 years after the Big Bang. Like a detective, the WMAP team compared the unique "fingerprint" of patterns imprinted on this ancient light with fingerprints predicted by various cosmic theories and found a match.
d) Composition of Universe - The contents of the Universe include 4% atoms, 23% of an unknown type of dark matter, and 73% of a mysterious dark energy. WMAP measurements also shed light on the nature of the dark energy, which acts as a sort of an anti-gravity.
Courtesy: NASA
SECTION 3: Cosmology Background Material
a) WMAP Science Objectives - Journey to the Big Bang (Animation) - WMAP was designed to capture the afterglow of the Big Bang. This animation takes the viewer backward through time to the first light in the Universe. We see: the Earth; the planets of the Solar System; and the Oort cloud beyond Pluto, thought to be where comets originate. Panning out, we see neighboring stars, nebulae, and our place in a spiral arm of the Milky Way galaxy and countless other galaxies. The deeper we probe, the farther back in time we look, for light from distant objects can take billions of years to reach us. We peer back to the quasar era, billions of light years from Earth, forming billions of years ago. Next we peer back into a condensation of gas forming the first stars, when the Universe was only 200,000 years. Next we see the dark ages, before starlight. Next we reach the era that WMAP observes, the moment that light breaks through the fog of the infant Universe. At the end, we observe the structure of matter and finally fade to white as we arrive at the big bang.
b) Wavelengths - Looking for the Earliest Light - On a clear, dark night, one can see a milky band of star light that we call the Milky Way, essentially diffuse light from the spiral arms of the Milky Way galaxy looking along the galactic plane. That's the view in the visible wavelengths, the light that our eyes detect. Different wavelengths -- gamma ray, X-ray, ultraviolet, infrared, microwave and radio -- reveal different aspects of the Universe. The first part of this sequence shows how the entire sky can be laid out flat on a map. The second part of this sequence depicts how dramatically our view of the sky changes as we move through the wavelengths like tuning a radio dial. In optical wavelengths, the band across the center is the Milky Way diffuse light. The microwave sky is astonishingly uniform. Scientists must view the sky with extreme contrast to see the subtle patterns from the earliest light in the Universe.
c) How WMAP Works: Ripples in a Pond - Ripples resulting from tossing pebbles in a pond are affected by the size and number of the pebbles and by the viscosity of the pond water. By studying ripples in the early Universe, scientists can gain a wealth of information about the makeup of the early Universe.
d) Measuring the Shape of the Universe - Like a lens, the shape of the Universe can bend the light that passes through it during its 13.7 billion year journey. By seeing the pattern today, we can determine the shape of the Universe -- whether it is flat, open or closed.
e) WMAP - Channels - WMAP observes the Universe at several different microwave frequencies to allow scientists to distinguish the Cosmic Microwave Background (the first and oldest light in the Universe) from microwave light produced in our Milky Way galaxy.
Courtesy: NASA
SECTION 4: WMAP Spacecraft Animation, Launch, and B-Roll
a) WMAP Animation - The WMAP spacecraft spins like a top to capture light from every part of the sky. The long conical horns on each side are shaped to receive photons that have been captured by a set of reflecting mirrors. The WMAP hardware and software were produced by NASA's Goddard Space Flight Center and Princeton University.
b) WMAP Journey to its L2 Orbit - WMAP took three months after its June 30, 2001, launch to reach the special Lagrange 2 orbit point where it makes its observations. WMAP is the first mission to use the stable L2 orbit as its permanent observing station.
c) WMAP Launch - WMAP was launched on June 30, 2001, aboard a Delta II launch vehicle from NASA's Kennedy Space Center.
d) Constructing WMAP - The WMAP Project is a partnership between NASA's Goddard Space Flight Center in Greenbelt, Md., and Princeton University. These scenes show WMAP's integration and testing at Goddard.
e) WMAP Integration - B-Roll of launch process of the WMAP spacecraft at NASA's Kennedy Space Center.
a) A Brief History of the Oldest Light in the Universe - Penzias and Wilson discovered the remnant afterglow from the big bang and were awarded the Nobel Prize for their discovery. COBE discovered the patterns in the afterglow. WMAP is bringing the patterns into much better focus to unveil a wealth of information about the history and fate of the Universe.
- Penzias and Wilson microwave receiver - 1965
- The sky viewed by Penzias and Wilson's microwave receiver - 1965
- COBE spacecraft animation
b) Comparison of COBE and WMAP Images
- COBE's view of early Universe - 1992 (First Image)
- WMAP view of early Universe - 2003 (Second Image)
- Comparison of COBE (Left) and WMAP (Right)
[GSFC Top Story Page]
GAMMA RAY BURST REVEALS DEATH, BIRTH, AND OTHER SURPRISES (G03-022) - Scientists have captured the spectacular death cry of an exploding star. The explosion resulted in the release of powerful jets of gamma rays, which were detected by NASA's High Energy Transient Explorer (HETE). Scientists say the biggest explosions in the Universe are larger than previously believed and that the collapsed star may have resulted in the birth of a brand new spinning black hole. These results appear in the March 20, 2003, issue of Nature.
ITEM (1): Gamma Ray Burst Death Cry Of An Exploding Star - Scientists have captured the spectacular death cry of an exploding star. The explosion resulted in the release of powerful jets of gamma rays, which were detected by HETE. Scientists say the biggest explosions in the Universe are larger than previously believed and that the collapsed star may have resulted in the birth of a brand new spinning black hole.
A Wolf-Rayet star in its final hours. Wolf-Rayet stars are extremely massive bluish stars, containing the mass of 10 to 15 suns. These stars burn so brightly that they shed their outer atmosphere, losing mass and becoming extremely hot in the process. The blue-white color of the star indicates that its surface temperature is approximately 50,000 C. Surrounding the star are wisps of gas that have recently been shed from the outer atmosphere. Diving through the surface of the Wolf-Rayet star, we come to the stellar core, about 10 percent the size of the whole star. We see shells of iron, oxygen, and carbon in the core, the ash of nuclear burning. This star is now out of fuel. Lacking energy to support its own mass, the core collapses and a black hole forms, pulling in matter. Yet a jet of material escapes through the Polar Regions, perhaps powered by renewed fusion and the spin of the black hole. The animation is nearly in real-time. We have now returned to the surface of the star, overlooking one of its poles. The core collapse and jet formation have all happened so quickly that the outer regions of the star have had no time to react they do not even know, yet, that it has happened. However, this region of the star is about to find out. The jet that we saw formed in the very center of the star is just now reaching the stellar surface. As it erupts through the surface and into the open space beyond, the material that it is carrying quickly accelerates to very near the speed of light, blasting outwards into the galaxy. The Wolf-Rayet star and its newly formed jets form a more distant perspective. We see that internal collisions of the jet material with itself are releasing energy photons that will eventually be observed as gamma rays by satellites in Earth orbit when the beam is pointed in our direction. Courtesy: NASA
ITEM (2): The "Rapid Response" Network Animation - Gamma-ray burst hunters are greatly aided by 3 new developments: fast triggers from orbiting detectors; fast relays to observers worldwide via the Gamma-Ray Burst Coordinates Network; and the fast responses from ground-based robotic telescopes. HETE is the first satellite to provide and distribute accurate burst locations within seconds. Courtesy: NASA
ITEM (3): Erupting Jet - This colorful image displays the jet erupting from the surface of the Wolf-Rayet star 9 seconds after its creating at the center of the star by the accreting black hole, which has a radius comparable to that of the sun. Blue represents regions of low mass concentration, red is denser, with yellow being denser still. Not the blue and red striations behind the head of the jet. These are bounded by internal shocks. Courtesy: NASA
ITEM (4): Breaking Out - This image shows the distribution of energy in the jet as it breaks out of the star. Yellow and orange depict very high energy, which will ultimately make a gamma-ray burst. Blue represents regions of lower energy. The larger angles that pour off the jet will produce x-ray flashes that may be seen more frequently. Courtesy: NASA
ITEM (5): High-Energy Transient Explorer (HETE) Animation - The High Energy Transient Explorer(HETE), a small scientific satellite, was designed to detect and localize gamma-ray bursts. This GRB was detected by HETE and distributed the coordinates to interested ground-based observers around the world within seconds, thereby allowing detailed observations of the initial phase over 50 telescopes in all. HETE-2 was successfully launched on October 9, 2000. Courtesy: NASA
ITEM (6): Understanding Gamma Ray Bursts (GRB's) Animation - Gamma rays are mysterious and fleeting flashes of high-energy radiation. They shine hundreds of times brighter than a supernova, or as bright as a million trillion suns! The bursts are common, yet random and fleeting lasting from a few milliseconds to 100 seconds. Courtesy: NASA
ITEM (7): Spinning Black Hole - Gamma rays are mysterious and fleeting flashes of high-energy radiation. They shine hundreds of times brighter than a supernova, or as bright as a million trillion suns. The bursts are common, random, and fleeting. They typically last from a few milliseconds to 100 seconds. Courtesy: NASA
[GSFC Top Story Page (3/19/03)]
RHESSI'S LUCKY BREAK MAY LEAD TO SECRET OF ULTIMATE EXPLOSIONS (G03-035) - NASA's Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite may have uncovered the secret of Gamma-ray bursts, the most powerful explosions in the universe, by a chance observation. The findings are were presented in a press conference at the American Astronomical Society meeting in Nashville, Tenn. on May 28, 2003.
ITEM (1): A Chance Observation - The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite was snapping pictures of solar flares on December 6, 2002, when it caught an extremely bright gamma-ray burst in the background, over the edge of the Sun, revealing for the first time that the gamma rays in such a burst are polarized. The result indicates intense magnetic fields may be the driving force behind these awesome explosions. Courtesy: NASA
ITEM (2): The Trigger: Enormous Magnetic Fields - The RHESSI observations provide a unique window on how these bursts are powered. The burst originates from a region of highly structured magnetic fields, stronger than the fields at the surface of a neutron star - until now, the strongest magnetic fields observed in the universe. Scientists say the magnetic fields [shown as gray lines] are acting as the dynamite, driving the explosive fireball we see as a gamma-ray burst. (Revised from G03-022)
Courtesy: NASA
[GSFC Top Story Page (5/28/03)]
"ROSETTA STONE" FOUND TO DECODE THE MYSTERY OF
GAMMA RAY BURSTS (G03-042) - Scientists have pieced together the key elements of a gamma ray burst, from star death to dramatic black hole birth, thanks to what they are calling a Rosetta Stone of such bursts observed on March 29, 2003. This telling March 29 burst in the constellation Leo, one of the brightest and closest on record, reveals for the first time that a gamma-ray burst and a supernova -- the two most energetic explosions known in the Universe -- occur nearly simultaneously, a quick and powerful one-two punch. The burst was detected by NASA's High-Energy Transient Explorer (HETE) and observed in detail with the European Southern Observatory's Very Large Telescope (VLT) at the Paranal Observatory in Chile.
ITEM (1): A Star's Collapse - Thousands of years prior to this explosion, a very massive star, running out of fuel, let loose much of its outer envelope, transforming itself into a bluish Wolf-Rayet star. The Wolf-Rayet star -- containing about 10 solar masses worth of helium, oxygen and heavier elements -- rapidly depleted its fuel, triggering the Type Ic supernova / gamma-ray burst event. The core collapsed, without the star's outer part knowing. Courtesy: NASA
ITEM (2): Gamma Ray Burst - A black hole formed inside surrounded by a disk of accreting matter, and, within a few seconds, launched a jet of matter away from the black hole that ultimately made the gamma-ray burst. The surface layers of the star blast outward, forming the colorful patterns typical of supernova remnants. Courtesy: NASA
ITEM (3): Theoretical Model Of The Creation Of A Gamma Ray Burst - This "collapsar" model, introduced by Woosley in 1993, best explains the observation of GRB 030329, as opposed to the "supranova" and "merging neutron star" models. As the core collapses, a jet of newly forged radioactive nickel-56 passes through the inner star toward the outer shell of the star and, in conjunction with vigorous winds blowing off the disk inside, shatters the star. This shattering represents the supernova event. Meanwhile, collisions among pieces of the jet moving at different velocities, all very close to light speed, created the gamma-ray burst. Courtesy: NASA
ITEM (4): HETE Spacecraft Animation - HETE was built by MIT as a mission of opportunity under the NASA Explorer Program, with collaboration among U.S. universities, Los Alamos National Laboratory, and scientists and organizations in Brazil, France, India, Italy and Japan. Courtesy: NASA/MIT
[GSFC Top Story Page (6/18/03)]
FIREHOSE-LIKE JET DISCOVERED IN ACTION - An X-ray movie of the Vela pulsar, made from a series of observations by NASA's Chandra X-ray Observatory, reveals a spectacularly erratic jet that varies in a way never seen before. The jet of high-energy particles whips about like an untended fire hose at about half the speed of light. This behavior gives scientists new insight into the nature of jets from pulsars and black holes.
Chandra observed the Vela pulsar, a rotating neutron star, 13 times between January 2000 and August 2002. These observations, which were designed to study the nature of the outflow of matter and antimatter from the pulsar led to the discovery that an outer jet of particles was bending and moving sideways at phenomenal speeds.
ITEM (1): X-Ray Movie Of Vela Pulsar From Chandra Observations - This sequence starts with ChandraÕs wide-field of the region around the Vela pulsar. The view then zooms into the area covered by Chandra during a series of 13 observations taken over about two and a half years. This movie led astronomers to discover an outer jet shooting out ahead of the moving pulsar. The most striking feature of the jet is its variability, changing both its shape and brightness. Meanwhile, bright blobs are seen moving along the jet with surprising velocities Ð at about half the speed of light. Courtesy: NASA/Chandra X-ray Observatory
[MSFC News Release #03-103 (6/30/03)]
EINSTEIN'S GRAVITATIONAL WAVES MAY SET SPEED LIMIT
FOR PULSAR SPIN (G03-044) - Scientists have identified a cosmic speed limit for millisecond pulsars, the fastest-spinning objects in the Universe, based on observations of eleven nuclear-powered pulsars whipping about at nearly 20 percent the speed of light.
A group led by Prof. Deepto Chakrabarty of the Massachusetts Institute of Technology analyzed data on eleven millisecond pulsars from the Rossi X-Ray Timing Explorer (RXTE) spacecraft. Based on a statistical analysis, Chakrabarty and his colleagues deduced that the maximum pulsar spin rate seen in nature is below 760 revolutions per second and concluded that something acts to prevent pulsars from being spun up to even faster rates. Their article appears in the July 3, 2003 issue of the journal Nature. Their work supports a theory proposed by Prof. Lars Bildsten, of the University of California, Santa Barbara that gravitational radiation - ripples in the fabric of space predicted by Albert Einstein - can limit pulsar spins.
ITEM (1): Accretion Spins Pulsar To Millisecond - When a pulsar is created in a supernova explosion, it is born spinning, but slows down over millions of years. Yet if the pulsar -- a dense star with strong gravitational attraction -- is in a binary system, then it can pull in, or accrete, material from its companion star. This influx of material can eventually spin up the pulsar to the millisecond range, rotating hundreds of revolutions per second. Courtesy: NASA
ITEM (2): Nuclear Explosions on Pulsar Surface Help Scientists Determine Spin Rate - Material accumulating on the pulsar surface can sometimes ignite, causing thermonuclear flashes that emit bursts of X-ray light. These thermonuclear flames spread across the surface of the pulsar in a few seconds. The team established that "burst oscillations", a kind of flickering, during these X-ray bursts provide a direct measure of the pulsar's spin rate. Thus, these bright bursts can be used to determine pulsar spin rates throughout the galaxy. This animation is a slow-motion depiction of a thermonuclear flash or X-ray burst spreading across a rotating pulsar. The pulsar would actually be rotating hundreds of revolutions per second. Courtesy: NASA
ITEM (3): Emitted Gravitational Radiation Halts Pulsar's Spin Up t - As the pulsar picks up speed through accretion, it becomes distorted from a perfect sphere due to subtle changes in the crust, depicted here by an equatorial bulge. Such slight distortion is enough to produce gravitational waves. Material flowing onto the pulsar surface from its companion star tends to quicken the spin, but loss of energy released as gravitational radiation tends to slow the spin due to the principle of conservation of energy. This competition may reach an equilibrium, setting a natural speed limit for millisecond pulsars beyond which they cannot be spun up. Courtesy: NASA
ITEM (4): Supernova Animation: Birth of A Pulsar - A supernova is associated with the death of a star about eighttimes as massive as the Sun or more. When such stars deplete their nuclear fuel, they no longer have the energy (in the form of radiation pressure outward) to support their mass. Their cores implode, forming either a neutron star (pulsar) or if there is enough mass, a black hole. The surface layers of the star blast outward, forming the colorful patterns typical of supernova remnants. Courtesy: NASA
[GSFC Top Story Page (7/2/03)]
CHANDRA "HEARS" A BLACK HOLE FOR THE FIRST TIME - NASA's Chandra X-ray Observatory detected sound waves, for the first time, from a super-massive black hole. The "note" is the deepest ever detected from an object in the universe. The tremendous amounts of energy carried by these sound waves may solve a longstanding problem in astrophysics.
The black hole resides in the Perseus cluster, located 250 million light years from Earth. In 2002, astronomers obtained a deep Chandra observation that shows ripples in the gas filling the cluster. These ripples are evidence for sound waves that have traveled hundreds of thousands of light years away from the cluster's central black hole.
ITEM (1): Animation of Sound Waves Generated in Perseus Cluster - This animation shows how sound waves are generated in the Perseus cluster from its central supermassive black hole. The gas that fills the cluster of galaxies is shown in red. The animation then zooms in to show the cluster's central black hole, which is seen as a white point. Next, blue-white jets of high-energy particles and magnetic fields blow out from the black hole, forming dark cavities in the cluster gas. When these cavities slow down, sound waves break off and travel away from the cavities. The animation then dissolves into Chandra's X-ray image of the cluster. Courtesy: NASA/Chandra X-ray Observatory
[MSFC News Release #03-152 (9/9/03)]
CHANDRA CAPTURES SPIRAL GALAXY'S VIOLENT, RESTLESS NATURE - A series of NASA Chandra X-ray Observatory images of the spiral galaxy NGC 1637 has provided a dramatic view of a violent, restless nature that belies the galaxy's serene optical image. Over a span of 21 months, intense neutron star and black hole X-ray sources flashed on and off, giving the galaxy the appearance of a cosmic Christmas tree. Erratic, volatile behavior is a common characteristic of neutron stars or black holes that orbit normal companion stars. Gas ripped off the normal star falls toward the compact star where the gas is compressed and heated by gravitational fields billions of times stronger than on the surface of the Sun. This process generates powerful X-radiation that can flare up and subside in a matter of seconds.
ITEM (1): NGC 1637 Time-lapse - A spiral galaxy 38 million light years from Earth. A series of Chandra observations of the spiral galaxy NGC 1637 has provided a dramatic view of a violent, restless nature that belies its serene optical image. Over a span of 21 months, intense neutron star and black hole X-ray sources flashed on and off, giving the galaxy the appearance of a cosmic Christmas tree. Courtesy: NASA/Chandra X-ray Observatory
[MSFC News Release #03-192 (10/28/03)]
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