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#91    Enigmatic Ghost

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Posted 14 May 2008 - 10:09 PM

Here is my Favorite image of Cassiopeia A in the center is a yellow dot it is the neutron star. Click upon image...

Pavot

Edited by Pavot, 14 May 2008 - 10:10 PM.


#92    Tiggs

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Posted 14 May 2008 - 10:28 PM

Waspie_Dwarf on May 14 2008, 02:31 PM, said:

The most recent supernova in our galaxy has been discovered by tracking the rapid expansion of its remains. This result, using NASA's Chandra X-ray Observatory and the National Radio Astronomy Observatory's Very Large Array, will help improve our understanding of how often supernovae explode in the Milky Way galaxy.

It's nice to see they've found a recent one original.gif


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#93    Waspie_Dwarf

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Posted 17 May 2008 - 07:56 AM

Youngest Stellar Explosion in Our Galaxy Discovered

The National Radio Astronomy Observatory press release is reproduced below:

May 14, 2008

Contact:


Dave Finley, Public Information Officer
Socorro, NM
(575) 835-7302
dfinley@nrao.edu

Astronomers have found the remains of the youngest supernova, or exploded star, in our Galaxy. The supernova remnant, hidden behind a thick veil of gas and dust, was revealed by the National Science Foundation's  Very Large Array (VLA) and NASA's Chandra X-Ray Observatory, which could see through the murk. The object is the first example of a "missing population" of young supernova remnants.

linked-image
VLA Images of G1.9+0.3 in 1985 and 2008: Circle for size comparison.
CREDIT
: Green, et al., NRAO/AUI/NSF

From observing supernovae in other galaxies, astronomers have estimated that about three such stellar explosions should occur in our Milky Way every century. However, the most recent one known until now occurred around 1680, creating the remnant called Cassiopeia A. The newly-discovered object is the remnant of an explosion only about 140 years ago.

"If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions in the Milky Way that are younger than Cassiopeia A," said David Green of the University of Cambridge in the UK, who led the VLA study. "It's great to finally track one of them down."

Supernova explosions, which mark the violent death of a star, release tremendous amounts of energy and spew heavy elements such as calcium and iron into interstellar space. They thus seed the clouds of gas and dust from which new stars and planets are formed and, through their blast shocks, can even trigger such formation.

The lack of evidence for young supernova remnants in the Milky Way had caused astronomers to wonder if our Galaxy, which appears otherwise normal, differed in some unknown way from others. Alternatively, scientists thought that the "missing" Milky Way supernovae perhaps indicated that their understanding of the relationship between supernovae and other galactic processes was in error.

The astronomers made their discovery by measuring the expansion of the debris from the star's explosion. They did this by comparing images of the object, called G1.9+0.3, made more than two decades apart.

In 1985, astronomers led by Green observed G1.9+0.3 with the VLA and identified it as a supernova remnant. At that time, they estimated its age as between 400 and 1,000 years. It is near the center of our Galaxy, roughly 25,000 light-years from Earth.

In 2007, another team of astronomers, led by Stephen Reynolds of North Carolina State University, observed the object with the Chandra X-Ray Observatory. To their surprise, their image showed the object to be about 16 percent larger than in the 1985 VLA image.

"This is a huge difference. It means the explosion debris is expanding very quickly, which in turn means the object is much younger than we originally thought," Reynolds explained. However, this expansion measurement came from comparing a radio image to an X-ray image.

To make an "apples to apples" comparison, the scientists sought and were quickly granted observing time on the VLA. "I've never seen a large astronomical institution move so fast," said Reynolds. Their new VLA observations confirmed the supernova remnant's rapid expansion.

The discovery provides scientists with a valuable source of new information about exploding stars. "Our previous situation was as if someone studying humans could look at babies and at adults, but could not study teenagers. Now, we're filling in that gap," said Reynolds.

The object already has provided surprises. The velocities of its explosion debris and extreme energies of its particles are unprecedented. "No other object in the Galaxy has properties like this," said Reynolds. "Finding G1.9+0.3 is extremely important for learning more about how some stars explode and what happens in the aftermath," he added.

The discovery was possible because radio and X-ray telescopes, unlike visible-light telescopes, can penetrate the thick clouds of gas and dust in our Galaxy. "Looking out of the Milky Way, we can see some supernova explosions with optical telescopes across half of the Universe, but when they're in this murk, we can miss them in our own cosmic back yard," Reynolds said.

"Fortunately, the expanding gas cloud from the explosion shines brightly in radio waves and X-rays for thousands of years. X-ray and radio telescopes can see through all that obscuration and show us what we've been missing," he added.

Because of the obscuration, no one could have seen the original explosion 140 years ago.

The astronomers are reporting their results in papers published in the Astrophysical Journal Letters and Monthly Notices of the Royal Astronomical Society.

Background Information: Supernova Explosions
Supernova explosions are the violent death throes of stars. These explosions release in one event as much energy as is being released by all the rest of the stars in a galaxy -- typically 100 billion or so. Supernovae seen in other galaxies can outshine the rest of their galaxy for days.

The supernovae that have occurred in our own Galaxy and were not obscured by the gas and dust that obscured G1.9+0.3 have often provided a spectacular sight. Historical records indicate that ancient astronomers noted supernova explosions at least as early as A.D. 393, and probably earlier. The pre-telescopic astronomers Tycho Brahe and Johannes Kepler made extensive observations of supernovae in 1572 and 1604. Chinese astronomers noted that a supernova in 1054 was bright enough to be seen in the daytime. A supernova in 1006 remained visible for two years.

Supernovae that result from the deaths of stars much more massive than the Sun enrich the galaxy with chemical elements that are produced in the cores of those stars before they explode. The heavy elements, such as carbon, oxygen, iron, siicon and calcium, that make up planets and their inhabitants were made available by supernova explosions.

In addition to enriching the material between stars with heavy elements, supernovae stir up that material through the shock energy of the explosion. This is thought to help trigger the process of star formation in interstellar clouds of gas and dust. Many astronomers believe that our own Solar System is the result of such a supernova shock.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.


Source: NRAO Press Release

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#94    Waspie_Dwarf

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Posted 17 May 2008 - 09:43 AM

Galactic Hunt Bags Missing Supernova

Editor's preface : Astronomers have long thought that supernovas explode two or three times a century here in the Milky Way. They arrive at that figure by watching other galaxies similar to our own, and counting the stars as they explode. But this leads to a mystery: The last time anyone actually saw a supernova explode in the Milky Way was the year 1680, almost 330 years ago. So where are the Milky Way's missing supernovas?

At long last, one of them has been found. Astronomers using NASA's Chandra X-ray Observatory (an x-ray telescope in space) and the NRAO's Very Large Array (a radio telescope in New Mexico) recently located the remains of a young supernova hiding in a dense field of gas and dust near the center of our galaxy. Read today's story to learn how a decades-long "galactic hunt" landed its prey.


May 14, 2008: The most recent supernova in our galaxy has been discovered by tracking the rapid expansion of its remains. This result, obtained by NASA's Chandra X-ray Observatory and the National Radio Astronomy Observatory's Very Large Array, will help improve our understanding of how often supernovas explode in the Milky Way galaxy.

The explosion occurred about 140 years ago, making it the most recent supernova in the Milky Way as measured in Earth's time frame. Previously, the last known supernova in our galaxy occurred around 1680, an estimate based on the expansion of its remnant, Cassiopeia A.

linked-image
Above: Young supernova remnant G1.9+0.3 is hidden in the dust fields of the galactic center. [more]

The remains of this young supernova are known to astronomers as "G1.9+0.3." The numbers denote the galactic coordinates of the supernova's expanding debris cloud, located deep in the heart of the Milky Way. The explosion itself was not seen because it occurred in a dense field of gas and dust. This made the object about a trillion times fainter, in optical light, than an unobscured supernova. However, the remnant it left behind can be seen by X-ray and radio telescopes.

"We can see some supernova explosions with optical telescopes across half of the universe, but when they're in this murk we can miss them in our own cosmic backyard," says Stephen Reynolds of North Carolina State University in Raleigh, who led the Chandra study. "Fortunately, the expanding gas cloud from the explosion shines brightly in radio waves and X-rays for thousands of years. X-ray and radio telescopes can see through all that obscuration and show us what we've been missing."

Astronomers regularly observe supernovas in other galaxies like ours. Based on those observations, researchers estimate about three explode every century in the Milky Way.

"If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions that are younger than Cassiopeia A," said David Green of the University of Cambridge in the United Kingdom, who led the Very Large Array study. "It's great to finally track one of them down."

The tracking of this object began in 1985, when astronomers, led by Green, used the Very Large Array to identify the remnant of a supernova explosion near the center of our galaxy. Based on its small size, it was thought to have resulted from a supernova that exploded about 400 to 1000 years ago.

Twenty-two years later, Chandra observations revealed the remnant had expanded by a surprisingly large amount, about 16 percent, since 1985. This indicates the supernova remnant is much younger than previously thought.

linked-image
Above: The supernova's expanding shell images by
Chandra in 2007. The central circle traces the shell's
approximate size in 1985[more]


That young age was confirmed in recent weeks when the Very Large Array made new radio observations. This comparison of data pinpoints the age of the remnant at 140 years - possibly less if it has been slowing down - making it the youngest on record in the Milky Way.

Besides being the record holder for youngest supernova, the object is of considerable interest for other reasons. The high expansion velocities and extreme particle energies that have been generated are unprecedented and should stimulate deeper studies of the object with Chandra and the Very Large Array.

"No other object in the galaxy has properties like this," Reynolds said. "This find is extremely important for learning more about how some stars explode and what happens in the aftermath."

These results are scheduled to appear in The Astrophysical Journal Letters.  

Editor: Dr. Tony Phillips | Credit: Science@NASA

____________________________________________

More Information

Chandra X-ray Observatory --mission home page

Credits: NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

NASA's Future: US Space Exploration Policy

Source: Science@NASA

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#95    Waspie_Dwarf

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Posted 03 June 2008 - 06:57 AM

NASA's Swift Satellite Catches a Star Going 'Kaboom!
05.21.08

When a gigantic star blows up, astronomers call it a "supernova." Over the past 100 years, astronomers have observed thousands of these explosions. But in every case, they were seeing the star after the explosion took place. They were seeing the hot debris from the explosion racing outward. It would be like seeing fireworks a few seconds after they go off, when the colorful lights are shooting away from the puff of smoke that mark the locations of the actual explosion.

Now, thanks to NASA’s Swift satellite, astronomers have seen a star actually blow up. The discovery is due to Swift’s capabilities and some alert astronomers, but also a bit of good luck.

linked-image
Swift took these images of SN 2007uy in galaxy
NGC 2770 before SN 2008D exploded. An X-ray
image is on top. The lower image is in visible light.
Credit: NASA/Swift Science Team/Stefan Immler.
> Larger image


On January 9, 2008, Alicia Soderberg and Edo Berger of Princeton University, in Princeton, N.J., were using Swift’s X-ray Telescope to observe a distant spiral-shaped galaxy known as NGC 2770. Suddenly, at 9:33 in the morning Eastern Time, the telescope picked up a powerful burst of X-rays coming from the galaxy. The burst lasted 5 minutes before it faded away.

Astronomers were fortunate that Swift happened to be looking at the right place at the right time when the burst occurred, but the great French biologist Louis Pasteur once said, "Chance favors the prepared mind." Soderberg and Berger immediately realized that Swift had made an important observation, so they quickly organized a plan to use telescopes in space and on Earth to follow-up Swift’s discovery.

Over the next few weeks, observations made by NASA’s Hubble Space Telescope and Chandra X-ray Observatory, along with Swift and other major telescopes, showed beyond a shadow of a doubt that the January 9 X-ray burst signaled the actual explosion of a giant star. For the first time, astronomers had seen a star blow up in real time!

The X-rays were due to a powerful blast wave bursting through the star’s outer layers, and blowing it to “Kingdom Come.” The blast wave itself was triggered deep inside the star, when the nuclear engine at the center ran out of fuel and collapsed. For decades, astronomers have been hoping to see such an explosion. And now, for the first time, they have actually seen what happens when a star goes supernova.

linked-image
On January 9 Swift caught a bright X-ray burst
from an exploding star. A few days later, SN 2008D
appeared in visible light.
Credit: NASA/Swift Science Team/Stefan Immler.
> Larger image


"For years we have dreamed of seeing a star just as it was exploding, but actually finding one is a once in a lifetime event," says Soderberg." This newly born supernova is going to be the Rosetta stone of supernova studies for years to come."

"It was a gift of nature for Swift to be observing that patch of sky when the supernova exploded. But thanks to Swift's flexibility, we have been able to trace its evolution in detail every day since," adds Swift lead scientist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md

Robert Naeye
NASA's Goddard Space Flight Center


Source: NASA - Swift

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#96    Waspie_Dwarf

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Posted 03 June 2008 - 07:02 AM

Strange Ring Found Circling Dead Star
05.28.08

Pasadena, Calif. -- NASA's Spitzer Space Telescope has found a bizarre ring of material around the magnetic remains of a star that blasted to smithereens.

The stellar corpse, called SGR 1900+14, belongs to a class of objects known as magnetars. These are the cores of massive stars that blew up in supernova explosions, but unlike other dead stars, they slowly pulsate with X-rays and have tremendously strong magnetic fields.

linked-image
This image shows a ghostly ring extending seven
light-years across around the corpse of a massive
star.
Image credit: NASA/JPL-Caltech


"The universe is a big place and weird things can happen," said Stefanie Wachter of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena, who found the ring serendipitously. "I was flipping through archived Spitzer data of the object, and that's when I noticed it was surrounded by a ring we'd never seen before." Wachter is lead author of a paper about the findings in this week's Nature. You can see the ring at _http://www.nasa.gov/mission_pages/spitzer/multimedia/20080528.html.

Wachter and her colleagues think that the ring, which is unlike anything ever seen before, formed in 1998 when the magnetar erupted in a giant flare. They believe the crusty surface of the magnetar cracked, sending out a flare, or blast of energy, that excavated a nearby cloud of dust, leaving an outer, dusty ring. This ring is oblong, with dimensions of about seven by three light-years. It appears to be flat, or two-dimensional, but the scientists said they can't rule out the possibility of a three-dimensional shell.

"It's as if the magnetar became a huge flaming torch and obliterated the dust around it, creating a massive cavity," said Chryssa Kouveliotou, senior astrophysicist at NASA's Marshall Space Flight Center, Huntsville, Ala., and a co-author of the paper. "Then the stars nearby lit up a ring of fire around the dead star, marking it for eternity."

The discovery could help scientists figure out if a star's mass influences whether it becomes a magnetar when it dies. Though scientists know that stars above a certain mass will "go supernova," they do not know if mass plays a role in determining whether the star becomes a magnetar or a run-of-the-mill dead star. According to the science team, the ring demonstrates that SGR 1900+14 belongs to a nearby cluster of young, massive stars. By studying the masses of these nearby stars, the scientists might learn the approximate mass of the original star that exploded and became SGR 1900+14.

"The ring has to be lit up by something, otherwise Spitzer wouldn't have seen it," said Enrico Ramirez-Ruiz of the University of California, Santa Cruz. "The nearby massive stars are most likely what's heating the dust and lighting it up, and this means that the magnetar, which lies at the exact center of the ring, is associated with the massive star-forming region."

Rings and spheres are common in the universe. Young, hot stars blow bubbles in space, carving out dust into spherical shapes. When stars die in supernova explosions, their remains are blasted into space, forming short-lived beautiful orbs called supernova remnants. Rings can also form around exploded stars whose expanding shells of debris ram into pre-existing dust rings, causing the dust to glow, as is the case with the supernova remnant called 1987A.

But the ring around the magnetar SGR 1900+14 fits into none of these categories. For one thing, supernova remnants and the ring around 1987A cry out with X-rays and radio waves. The ring around SGR 1900+14 only glows at specific infrared wavelengths that Spitzer can see.

At first, the astronomers thought the ring must be what's called an infrared echo. These occur when an object sends out a blast wave that travels outward, heating up dust and causing it to glow with infrared light. But when they went back to observe SGR 1900+14 later, the ring didn't move outward as it should have if it were an infrared echo.

A closer analysis of the pictures later revealed that the ring is most likely a carved-out cavity in a dust cloud -- a phenomenon that must be somewhat rare in the universe since it had not been seen before. The scientists plan to look for more of these rings.

"This magnetar is still alive in many ways," said Ramirez-Ruiz. "It is interacting with its environment, making a big impact on the young star-forming region where it was born."

Other paper authors include V. Dwarkadas of the University of Chicago, Ill.; J. Granot of the University of Hertfordshire, England; S.K. Patel of the Optical Sciences Corporation, Huntsville, Ala.; and D. Figer of the Rochester Institute of Technology, N.Y. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center. Caltech manages JPL for NASA. Spitzer's infrared array camera, which made the observations, was built by NASA's Goddard Space Flight Center, Greenbelt, Md. Its principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. For more information about Spitzer, visit _http://www.spitzer.caltech.edu/spitzer and _http://www.nasa.gov/spitzer

Media contact: Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.b.clavin@jpl.nasa.gov

2008-086


Source: NASA - Spitzer - News

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#97    Waspie_Dwarf

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Posted 03 June 2008 - 07:06 AM

Ghostly Ring
05.28.08

linked-image
This image shows a ghostly ring extending seven light-years across around the corpse of a massive star. The collapsed star, called a magnetar, is located at the exact center of this image. NASA's Spitzer Space Telescope imaged the mysterious ring around magnetar SGR 1900+14 in infrared light. The magnetar itself is not visible in this image, as it has not been detected at infrared wavelengths (it has been seen in X-ray light).

Magnetars are formed when a massive star ends its life in a supernova explosion, leaving behind a super dense neutron star with an incredibly strong magnetic field. The ring seen by Spitzer could not have formed during the original explosion, as any material as close to the star as the ring would have been disrupted by the supernova shock wave. Scientists suspect that the ring my actually be the edges of a bubble that was hollowed out by an explosive burst from the magnetar in 1998. The very bright region near the center of the image is a cluster of young stars, which may be illuminating the inner edge of the bubble, making it look like a ring in projection.

This composite image was taken using all three of Spitzer's science instruments. The blue color represents 8-micron infrared light taken by the infrared array camera, green is 16-micron light from the infrared spectograph, and red is 24-micron radiation from the multiband imaging photometer.

Image credit: NASA/JPL-Caltech

› Larger view (TIFF - 651Kb)

Source: NASA - Spitzer - Multimedia

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#98    Waspie_Dwarf

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Posted 03 June 2008 - 11:11 PM

Scientists Hold Seance for Supernova
05.29.08

Astronomers have unearthed secrets from the grave of a star that blasted apart in a supernova explosion long ago. By decoding ghostly echoes of light traveling away from the remains of a supernova called Cassiopeia A, the scientists have pieced together what the star looked like in life, and ultimately how it met its demise.

The discovery, made using primarily NASA's Spitzer Space Telescope and Japan's Subaru telescope on Mauna Kea in Hawaii, represents the first time astronomers have been able to resurrect the life history of a supernova remnant in our own galaxy.

linked-image
This image shows the remnant of a star that exploded,
called Cassiopeia A (center) and its surrounding
"light echoes."
Image credit: NASA/JPL-Caltech


"Cassiopeia A lies in our cosmic backyard and offers the sharpest view of what is left hundreds of years after a supernova explosion," said Oliver Krause of the Max Planck Institute for Astronomy in Germany, lead author of a paper about the discovery appearing in this week's Science. "The echoes of light we found around Cassiopeia A provide us with a time machine to go back and see its past."

Cassiopeia A is one of the most explored objects in our sky and the subject of more than 1,000 scientific papers. It is the burnt-out corpse of a massive star that ended its life in a fiery supernova about 11,300 years ago. In fact, until recently, it was the youngest supernova remnant in our Milky Way galaxy (the new record holder, G1.9+0.3, was recently discovered using NASA's Chandra X-ray Observatory and other ground-based telescopes). Because Cassiopeia A is 11,000 light-years from Earth, the light from its explosion would have reached Earth, sweeping right past it, about 300 years ago.

linked-image
In this animation, a seething cauldron of light
appears to bubble and ooze around the remains of
a giant star.
Credit: NASA/JPL-Caltech/MPIA
›  Go to animation


Astronomers had thought this supernova light was never to be seen again, until 2005, when Krause and his colleagues discovered hints of it still bouncing around clouds surrounding the remnant (_http://www.spitzer.caltech.edu/Media/releases/ssc2005-14/index.shtml ). Using Spitzer's infrared eyes, they found so-called infrared echoes, which occur when a flash of light from the supernova blasts through clouds, heating them up and causing them to glow in infrared. As the light rolls outward, the infrared echoes continue to flare up and travel away from the star (see new movie of this effect at _http://www.nasa.gov/mission_pages/spitzer/multimedia/20080529-anim.html).

In the new study, the astronomers used Cassiopeia A's infrared echoes to hone in on faint visible-light echoes with Subaru and other ground-based telescopes. Visible-light echoes, known simply as light echoes, occur when visible light from the supernova scatters off dust. Unlike infrared echoes, they are direct signals from the graves of exploded stars, bearing all the information about the nature of the original blast.

Next, the astronomers had to act quickly because these echoes can fade within weeks. They used Subaru's spectrometer instrument to break the light apart and reveal signatures of atoms present when Cassiopeia A exploded. The resulting spectrum of light revealed hydrogen and helium -- telltale signs that Cassiopeia A was once a huge red supergiant star whose core collapsed in a rare supernova referred to as Type IIb. Previously, scientists did not know the supernova class to which Cassiopeia A belonged.

"This is an exciting result," said Alex Filippenko of the University of California, Berkeley, a supernova expert not affiliated with the study. "Cassiopeia A has been studied extensively with many telescopes over a wide range of wavelengths. It is gratifying that we finally know what kind of star exploded so long ago."

The findings also offer insight into another mystery shrouding Cassiopeia A. When Cassiopeia A's original star erupted, the event should have been widely witnessed on Earth as a bright star lighting up the sky. The most likely possible sighting is by the Astronomer Royal John Flamsteed in 1680, but he made just one observation of a dim star. The fact that almost no one saw the event is a classic problem in supernova lore.

Now that astronomers have learned how Cassiopeia A was forged, they think they might know why its death went unnoticed. "Type IIb supernovas fade quickly," said co-author George Rieke of the University of Arizona in Tucson. "This, plus a few cloudy nights, might explain the historical enigma around Cassiopeia A."

Recently, astronomers using Chandra, ESA's XMM-Newton Observatory and the Gemini Observatory in Chile, were able to use light echoes to identify the origins of a supernova outside our galaxy. That study, together with the new one, demonstrates the power of light echoes for conjuring up the "ghosts" of long-dead stars.

Other co-authors include Stephan Birkmann and Miwa Goto of the Max Planck Institute for Astronomy; Tomonori Usuda and Takashi Hattori of the National Astronomical Observatory of Japan in Hawaii; and Karl Misselt of the University of Arizona. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the California Institute of Technology, also in Pasadena. For more information about Spitzer, visit _http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer . For more information about Subaru, operated by the National Astronomical Observatory of Japan, visit _http://subarutelescope.org .

Media contact: Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.b.clavin@jpl.nasa.gov

2008-088


Source: NASA - Spitzer - News

Edited by Waspie_Dwarf, 03 June 2008 - 11:13 PM.

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#99    Waspie_Dwarf

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Posted 03 June 2008 - 11:22 PM

Dance of the Light Echoes
05.29.08

linked-image
This composite image from NASA's Spitzer Space Telescope shows the remnant of a star that exploded, called Cassiopeia A (center) and its surrounding "light echoes" -- dances of light through dusty clouds, created when stars blast apart. The light echoes are colored and the surrounding clouds of dust are gray.

A light echo occurs when a star explodes, acting like a cosmic flashbulb. The light from this explosion zips through nearby dust clumps, illuminating and heating them up slightly. This brief period of warming causes them to glow in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light.

Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion. 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 is located 11,000 light-years away in the northern constellation Cassiopeia.

This composite consists of six processed images taken over a time span of three years. Dust features that have not changed over time appear gray, while those that have changed are colored blue or orange. Bluer colors represent an earlier time and redder ones, a later time. The progression of the light echo through the dust can be seen here by the shift in colored dust clumps.

This light echo is the largest ever seen, stretching more than 300 light-years away from Cassiopeia A. If viewed from Earth, the entire frame would take up the same amount of space as seven full moons.

The earliest Spitzer image shown here was taken in February 2005, and the latest one in January 2008. The image was processed to emphasize the light echo by enhancing the areas that change, which appear in color, and dimming regions that remain constant, seen in grayscale. Spurious color artifacts such as diffraction spikes around stars were removed by hand.

Image credit: NASA/JPL-Caltech

› High-resolution JPEG (4.5Mb)

Source: NASA - Spitzer - Multimedia

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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#100    Waspie_Dwarf

Waspie_Dwarf

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Posted 03 June 2008 - 11:31 PM

Ghostly Stellar Echoes
05.29.08

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This image from NASA's Spitzer Space Telescope highlights dramatic changes in phenomena referred to as light echoes (colored areas) around the Cassiopeia A supernova remnant (center). Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died.

A light echo is created when a star explodes or erupts, flashing light into surrounding clumps of dust. As the light zips through the dust clumps, it heats them up, causing them to glow successively in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. This apparent motion can be seen here by the shift in colored dust clumps.

The main underlying image is a composite from Spitzer showing Cassiopeia A and surrounding interstellar clouds of dust. It consists of six images taken over a time span of three years, each represented in a different color, as noted by the key at the bottom of the image.

Dust features that have not changed over time appear gray, while those that have changed are colored blue or orange. Bluer colors represent an earlier time and redder ones, a later time. Certain areas of the light echo are displayed in more detail to show the turbulent patterns formed as the light echo illuminates different areas of gas and dust over time.

The supernova remnant is located 11,000 light-years away in the northern constellation Cassiopeia. The light echo is the largest ever seen, stretching more than 300 light-years away from Cassiopeia A. If viewed from Earth, the entire frame would take up the same amount of space as seven full moons.

The earliest Spitzer image shown here was taken in February 2005, and the latest one in January 2008. The image was processed to emphasize the light echo by enhancing the areas that change, which appear in color, and dimming regions that remain constant, seen in gray. Spurious color artifacts, such as diffraction spikes around stars, were removed by hand.

Image credit: NASA/JPL-Caltech/MPIA

› Full resolution TIFF (8.8Mb)

Source: NASA - Spitzer - Multimedia

"Space is big. Really big. You just won't believe how vastly, hugely, mind-boggingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space." - The Hitch-Hikers Guide to the Galaxy - Douglas Adams 1952 - 2001

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