Author Topic: NASA - Spitzer Updates  (Read 45700 times)

Offline jacqmans

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NASA - Spitzer Updates
« on: 08/31/2006 08:05 pm »
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

Image Advisory:   2006-103                                                         August 31, 2006

 

The Eternal Life of Stardust Portrayed in New NASA Image


A new image from NASA's Spitzer Space Telescope is helping astronomers understand how stardust is recycled in galaxies.

The cosmic portrait shows the Large Magellanic Cloud, a nearby dwarf galaxy named after Ferdinand Magellan, the seafaring explorer who observed the murky object at night during his fleet's historic journey around Earth.  Now, nearly 500 years after Magellan's voyage, astronomers are studying Spitzer's view of this galaxy to learn more about the circular journey of stardust, from stars to space and back again.

"The Large Magellanic Cloud is like an open book," said Dr. Margaret Meixner of the Space Telescope Science Institute, Baltimore, Md. "We can see the entire lifecycle of matter in a galaxy in this one snapshot." Meixner is lead author of a paper on the findings to appear in the November 2006 issue of the Astronomical Journal.

The vibrant false-color image, a mosaic of approximately 300,000 individual frames, shows a central blue sea of stars amidst lots of colorful, choppy waves of dust.  It can be viewed at:

http://www.spitzer.caltech.edu/Media/releases/ssc2006-17/ssc2006-17b.shtml .  

Space dust is important for making stars, planets and even people. The tiny particles -- flecks of minerals, ices and carbon-rich molecules -- are everywhere in the universe. Developing stars and solar systems are constantly consuming dust, while older stars shed dust back into space, where it will one day provide the ingredients for new generations of stars.

Spitzer, an infrared observatory orbiting the sun, is extremely sensitive to the infrared glow of dust that arises when stars heat it up. The observatory's unprecedented view of the Large Magellanic Cloud offers a unique look at three stops on the eternal ride of dust through a galaxy: in collapsing envelopes around young stars; scattered about in the space between stars; and in expelled shells of material from old stars.

"The Spitzer observations of the Large Magellanic Cloud are giving us the most detailed look yet at how this feedback process works in an entire galaxy," said Meixner. "We can quantify how much dust is being consumed and ejected by stars."

In addition to dust, Spitzer's view reveals nearly one million never-before-seen objects, most of which are stars in the Large Magellanic Cloud. The hidden stars, both young and old, are embedded in layers of dust that block visible starlight but shine in infrared.

"We can now see the populations of old stars and stars that are currently forming," said co-author Dr. Karl Gordon of the University of Arizona, Tucson.

The Large Magellanic Cloud is one of a handful of dwarf galaxies that orbit our own Milky Way. It is located near the southern constellation Dorado, about 160,000 light-years from Earth.  About one-third of the whole galaxy can be seen in the Spitzer image.

Astronomers believe that approximately six billion years ago, not long before our solar system formed, this dwarf galaxy was shaken up via a close encounter with the Milky Way. The resulting chaos triggered bursts of massive star formation similar to what is thought to occur in more primitive galaxies billions of light-years away. This and other distant-galaxy traits, such as an irregular shape and low abundance of metals, make the Large Magellanic Cloud the perfect nearby target for studying the faraway universe.

This research is part of a Spitzer Legacy program called Surveying the Agents of a Galaxy's Evolution, also known as Sage. The international Sage team includes more than 50 astronomers spread over the globe from Japan to the United States.  The main data centers are located at: the Space Telescope Science Institute, Baltimore, Md., led by Meixner; University of Arizona, Tucson, led by Gordon; and University of Wisconsin, Madison, led by Dr. Barbara Whitney.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera and multiband imaging photometer captured the new image. The camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. Its principal investigator is Dr. Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. The photometer was built by Ball Aerospace Corporation, Boulder, Colo.; the University of Arizona; and Boeing North American, Canoga Park, Calif. Its principal investigator is Dr. George Rieke of the University of Arizona, Tucson.


For more information about Spitzer visit www.spitzer.caltech.edu/spitzer.


-end-
Jacques :-)

Offline jacqmans

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Re: NASA - Spitzer Updates
« Reply #1 on: 08/25/2007 07:32 am »
Spitzer Celebrates Fourth Anniversary with Celestial Fireworks

A newly expanded image of the Helix nebula lends a festive touch to the fourth anniversary of the launch of NASA's Spitzer Space Telescope.  This spectacular object, a dying star unraveling into space, is a favorite of amateur and professional astronomers alike.  Spitzer has mapped the expansive outer structure of the six-light-year-wide nebula, and probed the inner region around the central dead star to reveal what appears to be a planetary system that survived the star's chaotic death throes.

Spitzer launched from Cape Canaveral, Fla., on August 25, 2003.  In its four years of operations, Spitzer has provided unprecedented infrared views of objects as diverse as asteroids in our own solar system to galaxies at the edge of the observable universe.  Recent discoveries include the first detection of water vapor on a planet orbiting another star and a titanic galactic collision five billion light-years away.

"With Spitzer, we have achieved scientific discoveries far beyond our wildest expectations," said Michael Werner, project scientist for Spitzer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "A large part of our success is due to the smooth and efficient operations of the spacecraft."

Another cause for celebration is Spitzer's excellent technical performance. Spitzer is the first infrared space telescope to use an Earth-trailing orbit and passive cooling techniques, such as a sun shield, to obtain the low temperatures required for an infrared observatory.  The design allowed for a much smaller tank of liquid-helium coolant, or cryogen, to chill the telescope, thereby slashing mission costs.

The minimum expected lifetime of Spitzer was only two-and-one-half years. Now, Spitzer's cryogen is expected to last much longer, giving the mission a lifetime of more than five-and-one-half years.

  "I think it's safe to say that the novel Spitzer design has been validated," said Werner.  "We've broken all records for the longest lifetime using the smallest amount of cryogen, and we still have another year and a half to go."

JPL is responsible for the operations of the Spitzer spacecraft, while science operations are conducted at the Spitzer Science Center at the California Institute of Technology, Pasadena, Calif.  Spacecraft engineering is carried out by Lockheed Martin, Denver, Colo., with help from Ball Aerospace Corporation, Boulder, Colo.

For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer or http://www.nasa.gov/spitzer .

-end-

Jacques :-)

Offline jacqmans

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Re: NASA - Spitzer Updates
« Reply #2 on: 10/23/2007 03:12 am »
Feature                                           October 22, 2007                    


 To Catch a Galactic Thief

On Earth, thieves steal everything from diamonds to art to bags full of money. In space, gas – fuel for making stars – is a commodity worth the price of theft.

New observations from NASA's Spitzer Space Telescope reveal a distant, massive galaxy in the act of ripping off vast reservoirs of gas – the equivalent of one billion suns – from its smaller, neighbor galaxy. The stolen gas, which has become scorching hot during the heist, will likely cool down and get turned into new stars and planets.

"We may be viewing the larger galaxy in a rare, brief stage of its reincarnation from an old galaxy to a youthful one studded with brilliant stars," said Patrick Ogle of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena, Calif. Ogle is the lead author of a new paper on the findings in the Oct. 20 issue of the Astrophysical Journal.

The robber galaxy, called 3C 326 North, is about the mass of our Milky Way galaxy, and its victim, 3C 326 South, is about half its mass. They are close enough to perturb each other gravitationally and might eventually collide. Such galaxy mergers are common in the universe: Gas and stars in two nearby galaxies become tangled until they join up into one seamless galaxy. The case of 3C 326 is the clearest example yet of large quantities of gas being heated and siphoned from one galaxy to another.

"This could be an important phase in galaxy mergers that we are just now witnessing," said Ogle.

Ogle and his colleagues initially set out to study a set of distant galaxies, called radio galaxies, about one billion light-years away. Radio galaxies are named after the radio-emitting jets that scream out of the black holes at their centers. Though these jets are powerful, their black holes are relatively sleepy and don't otherwise give off a lot of energy. When the astronomers scanned 72 galaxies using Spitzer's infrared vision, they noted a handful that were quite unusual.

The most extreme of the bunch, 3C 326 North, was soaking in an enormous amount of hot hydrogen gas, reaching temperatures up to 730 degrees Celsius (1,340 degrees Fahrenheit). This gas, called molecular hydrogen gas because it contains molecules of two hydrogen atoms joined together, is a building block of galaxies, stars and planets. On Earth, it is a potential alternative fuel for cars. Molecular hydrogen gas is invisible to optical telescopes, but when it's heated up it glows at infrared wavelengths that Spitzer can see.

"Hydrogen is by far the predominant element in the universe, yet in its molecular form it has been virtually undetectable until Spitzer launched," said co-author Robert Antonucci of the University of California, Santa Barbara .

Since 3C 326 North is not busy making new stars, it is unusual for it to have this much gas. When the researchers investigated the Spitzer pictures further, they noticed what appeared to be a tail of stars, called a tidal tail, connecting 3C 326 North to 3C 326 South. That was the smoking gun they needed to realize that the pair were interacting, and that 3C 326 North was lifting the gas right off its companion's back.

"The galaxy in question appears to be stripping a large quantity of molecular hydrogen from its neighbor and heating it up," said Ogle. "The supermassive black hole at the center of the galaxy is digesting a small fraction of the gas and ejecting it in enormous, relativistic jets millions of light-years long."

In addition, the hydrogen gas is hot enough to react with oxygen and form vast quantities of water. This water could potentially be incorporated into planets and comets once the gas has cooled enough to collapse and form new stars and planetary systems.

What will happen to the victim galaxy now that it is bereft of its gas? According to Ogle, the galaxy lost a lot of its fuel, and will no longer produce new stars. However, if the two galaxies do eventually merge, then what belongs to one will belong to the other!

Other authors of this paper include: Phil N. Appleton of Caltech; and David Whysong of the National Radio Astronomy Observatory, headquartered in Charlottesville, Va.

For graphics and more information about Spitzer, visit www.spitzer.caltech.edu/spitzer and www.nasa.gov/spitzer .

Jacques :-)

Offline jacqmans

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Re: NASA - Spitzer Updates
« Reply #3 on: 11/08/2007 06:42 pm »
November 8, 2007                          


Spitzer Spies a Stellar Bubble Blower

A new image from NASA's Spitzer Space Telescope shows a baby star 1,140 light-years away from Earth blowing two massive "bubbles." But instead of bubble gum, this youngster, called HH 46/47, is using powerful jets of gas to make bubbles in outer space.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are from starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. Red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

According to Thangasamy Velusamy of NASA's Jet Propulsion Laboratory in Pasadena, Calif., baby stars and their potential planet-forming disks grow by gravitationally pulling in and absorbing surrounding gas and dust. Scientists suspect that these disks stop growing when the central baby star develops powerful winds and jets that blow away surrounding material.

"Spitzer can image these jets and winds in infrared light and help us understand the details of these phenomena," says Velusamy.

For astronomers who know what to look for, Spitzer's supersensitive infrared instruments are excellent tools for studying young stars embedded within thick clouds of cosmic dust and gas, revealing information about their growth. However, Velusamy notes that it is often difficult for most people to get a clear, detailed picture of infant stars and their "growing pains."

"When you see a star through a telescope, its image is blurred in a known way, and the smaller the telescope the larger is the blurring," he says.

To clear up this blurring, astronomers at JPL developed an advanced image-processing technique for Spitzer data called Hi-Res deconvolution. This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When Velusamy and his team applied this technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

According to William Langer, also of JPL, this image will help scientists determine which of many different mechanisms are responsible for producing the winds and jets of baby stars.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

This paper on HH46/47 by Velusamy, Langer, and Kenneth Marsh, all of JPL, was published in the October issue of Astrophysical Journal Letters.

Written by Linda Vu

Media contact: Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

 
Jacques :-)

Offline jacqmans

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Re: NASA - Spitzer Updates
« Reply #4 on: 11/20/2007 06:47 pm »

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
NEWS RELEASE: 2007-132                                                   Nov. 20, 2007

Astronomers Say Moons Like Ours Are Uncommon

The next time you take a moonlit stroll, or admire a full, bright-white moon looming in the night sky, you might count yourself lucky. New observations from NASA's Spitzer Space Telescope suggest that moons like Earth’s – that formed out of tremendous collisions – are uncommon in the universe, arising at most in only 5 to 10 percent of planetary systems.

"When a moon forms from a violent collision, dust should be blasted everywhere," said Nadya Gorlova of the University of Florida, Gainesville, lead author of a new study appearing Nov. 20 in the Astrophysical Journal. "If there were lots of moons forming, we would have seen dust around lots of stars – but we didn't."

It's hard to imagine Earth without a moon. Our familiar white orb has long been the subject of art, myth and poetry. Wolves howl at it, and humans have left footprints in its soil. Life itself might have evolved from the ocean to land thanks to tides induced by the moon's gravity.

Scientists believe the moon arose about 30 to 50 million years after our sun was born, and after our rocky planets had begun to take shape. A body as big as Mars is thought to have smacked into our infant Earth, breaking off a piece of its mantle. Some of the resulting debris fell into orbit around Earth, eventually coalescing into the moon we see today. The other moons in our solar system either formed simultaneously with their planet or were captured by their planet's gravity.

Gorlova and her colleagues looked for the dusty signs of similar smash-ups around 400 stars that are all about 30 million years old – roughly the age of our sun when Earth's moon formed. They found that only 1 out of the 400 stars is immersed in the telltale dust. Taking into consideration the amount of time the dust should stick around, and the age range at which moon-forming collisions can occur, the scientists then calculated the probability of a solar system making a moon like Earth's to be at most 5 to 10 percent.

"We don't know that the collision we witnessed around the one star is definitely going to produce a moon, so moon-forming events could be much less frequent than our calculation suggests," said George Rieke of the University of Arizona, Tucson, a co-author of the study.

In addition, the observations tell astronomers that the planet-building process itself winds down by 30 million years after a star is born. Like our moon, rocky planets are built up through messy collisions that spray dust all around. Current thinking holds that this process lasts from about 10 to 50 million years after a star forms. The fact that Gorlova and her team found only 1 star out of 400 with collision-generated dust indicates that the 30-million-year-old stars in the study have, for the most part, finished making their planets.

"Astronomers have observed young stars with dust swirling around them for more than 20 years now," said Gorlova. "But those stars are usually so young that their dust could be left over from the planet-formation process. The star we have found is older, at the same age our sun was when it had finished making planets and the Earth-moon system had just formed in a collision."

For moon lovers, the news isn't all bad. For one thing, moons can form in different ways. And, even though the majority of rocky planets in the universe might not have moons like Earth's, astronomers believe there are billions of rocky planets out there. Five to 10 percent of billions is still a lot of moons.

Other authors of the paper include: Zoltan Balog, James Muzerolle, Kate Y. L. Su and Erick T. Young of the University of Arizona, and Valentin D. Ivanov of the European Southern Observatory, Chile.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .
Jacques :-)

Offline jacqmans

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Re: NASA - Spitzer Updates
« Reply #5 on: 03/13/2008 06:39 pm »
NEWS RELEASE: 2008-042                                                             March 13, 2008

Spitzer Finds Organics and Water Where New Planets May Grow

Researchers using NASA's Spitzer Space Telescope have discovered large amounts of simple organic gases and water vapor in a possible planet-forming region around an infant star, along with evidence that these molecules were created there. They've also found water in the same zone around two other young stars.

By pushing the telescope's capabilities to a new level, astronomers now have a better view of the earliest stages of planetary formation, which may help shed light on the origins of our own solar system and the potential for life to develop in others.

John Carr of the Naval Research Laboratory, Washington, and Joan Najita of the National Optical Astronomy Observatory, Tucson, Ariz., developed a new technique using Spitzer's infrared spectrograph to measure and analyze the chemical composition of the gases within protoplanetary disks. These are flattened disks of gas and dust that encircle young stars. Scientists believe they provide the building materials for planets and moons and eventually, over millions of years, evolve into orbiting planetary systems like our own.

"Most of the material within the disks is gas," said Carr, "but until now it has been difficult to study the gas composition in the regions where planets should form. Much more attention has been given to the solid dust particles, which are easier to observe."

In their project, Carr and Najita took an in-depth look at the gases in the planet-forming region in the disk around the star AA Tauri. Less than a million years old, AA Tauri is a typical example of a young star with a protoplanetary disk.

With their new procedures, they were able to detect the minute spectral signatures for three simple organic molecules--hydrogen cyanide, acetylene and carbon dioxide--plus water vapor. In addition, they found more of these substances in the disk than are found in the dense interstellar gas called molecular clouds from which the disk originated. "Molecular clouds provide the raw material from which the protoplanetary disks are created," said Carr. "So this is evidence for an active organic chemistry going on within the disk, forming and enhancing these molecules."

Spitzer's infrared spectrograph detected these same organic gases in a protoplanetary disk once before. But the observation was dependent on the star's disk being oriented in just the right way. Now researchers have a new method for studying the primordial mix of gases in the disks of hundreds of young star systems.

Astronomers will be able to fill an important gap--they know that water and organics are abundant in the interstellar medium but not what happens to them after they are incorporated into a disk. "Are these molecules destroyed, preserved or enhanced in the disk?" said Carr. "Now that we can identify these molecules and inventory them, we will have a better understanding of the origins and evolution of the basic building blocks of life--where they come from and how they evolve." Carr and Najita's research results appear in the March 14 issue of Science.

Taking advantage of Spitzer's spectroscopic capabilities, another group of scientists looked for water molecules in the disks around young stars and found them--twice. "This is one of the very few times that water vapor has been directly shown to exist in the inner part of a protoplanetary disk–the most likely place for terrestrial planets to form," said Colette Salyk, a graduate student in geological and planetary sciences at the California Institute of Technology in Pasadena. She is the lead author on a paper about the results in the March 20 issue of Astrophysical Journal Letters.

Salyk and her colleagues used Spitzer to look at dozens of young stars with protoplanetary disks and found water in many. They honed in on two stars and followed up the initial detection of water with complementary high-resolution measurements from the Keck II Telescope in Hawaii. "While we don't detect nearly as much water as exists in the oceans on Earth, we see essentially only the disk's surface, so the implication is that the water is quite abundant," said Geoffrey Blake, professor of cosmochemistry and planetary sciences at Caltech and one of the paper's co-authors.

"This is a much larger story than just one or two disks," said Blake. "Spitzer can efficiently measure these water signatures in many objects, so this is just the beginning of what we will learn."

"With upcoming Spitzer observations and data in hand," Carr added, "we will develop a good understanding of the distribution and abundance of water and organics in planet-forming disks."

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 Spitzer Science Center at Caltech, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #6 on: 06/03/2008 07:49 pm »
IMAGE ADVISORY: 2008-095                                                                     June 3, 2008

Spitzer Captures Stellar Coming of Age in Our Galaxy

More than 800,000 snapshots from NASA's Spitzer Space Telescope have been stitched together to create a new "coming of age" portrait of stars in our inner Milky Way galaxy.

The image, which depicts an area of sky 120 degrees wide by two degrees tall, can be viewed at http://www.nasa.gov/mission_pages/spitzer/multimedia/20080603.html . It was unveiled today at the 212th meeting of the American Astronomical Society in St. Louis, Mo.

"This is the highest-resolution, largest, most sensitive infrared picture ever taken of our Milky Way," said Sean Carey of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena, Calif. Carey is lead investigator for one of two teams responsible for the new picture. "Where previous surveys saw a single source of light, we now see a cluster of stars. With this data, we can learn how massive stars form, map galactic spiral arms and make a better estimate of our galaxy's star-formation rate," Carey explained.

"I suspect that Spitzer's view of the galaxy is the best that we'll have for the foreseeable future. There is currently no mission planned that has both a wide field of view and the sensitivity needed to probe the Milky Way at these infrared wavelengths," said Barbara Whitney of the Space Science Institute, Madison, Wis. Whitney is a member of the second astronomy team.

Because Earth sits inside our dusty, flat, disk-shaped Milky Way, we have an edge-on view of our galactic home. We see the Milky Way as a blurry, narrow band of light that stretches almost completely across the sky. With Spitzer's dust-piercing infrared eyes, astronomers peered 60,000 light-years away into this fuzzy band, called the galactic plane, and saw all the way to the other side of the galaxy.

The result is a cosmic tapestry depicting an epic coming-of-age tale for stars. Areas hosting stellar embryos are identified by swaths of green, which are organic molecules, called polycyclic aromatic hydrocarbons, illuminated by light from nearby newborn stars. On Earth, these molecules are found in automobile exhaust and charred barbeque grills, essentially anywhere carbon molecules are burned incompletely.   

The regions where young stars reside are revealed as "bubbles," or curved ridges in the green clouds. These bubbles are carved by the winds from young starlets blowing away their natal dust. The starlets appear as yellow and red dots, and the wisps of red that fill most bubbles are composed of graphite dust particles, similar to very small pieces of pencil lead.

Blue specks sprinkled throughout the photograph are individual older Milky Way stars. The bluish-white haze that hovers heavily in the middle two panels is starlight from the galaxy's older stellar population. A deep, careful examination of the image also shows the dusty remnants of dying and dead stars as translucent orange spheres.

"With these Spitzer data, we've been able to catalogue more than 100 million stars," said Edward Churchwell of the University of Wisconsin, at Madison. Churchwell is principal investigator of one of the teams.

"This picture shows us that our Milky Way galaxy is a crowded and dynamic place. We have a lot to learn. I've definitely found a lot of things in this map that I didn't expect to see," said Carey.

This infrared composite incorporates observations from two Spitzer instruments. Data from the infrared array camera were collected and processed by The Galactic Legacy Infrared Mid-Plane Survey Extraordinaire team, led by Churchwell. The Multiband Imaging Photometer for Spitzer Galactic Plane Survey Legacy team, led by Carey, processed observations from Spitzer's multiband imaging photometer. Blue represents 3.6-micron light, green shows light of 8 microns and red is 24-micron light.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer.

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #7 on: 07/10/2008 07:09 pm »
News Release: 2008-129                                July 10, 2008

Rare 'Star-Making Machine' Found in Distant Universe

Astronomers have uncovered an extreme stellar machine -- a galaxy in the very remote universe pumping out stars at a surprising rate of up to 4,000 per year. In comparison, our own Milky Way galaxy turns out an average of just 10 stars per year.

The discovery, made possible by several telescopes including NASA's Spitzer Space Telescope, goes against the most common theory of galaxy formation. According to the theory, called the Hierarchical Model, galaxies slowly bulk up their stars over time by absorbing tiny pieces of galaxies -- and not in one big burst as observed in the newfound "Baby Boom" galaxy. 

"This galaxy is undergoing a major baby boom, producing most of its stars all at once," said Peter Capak of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena. "If our human population was produced in a similar boom, then almost all of the people alive today would be the same age." Capak is lead author of a new report detailing the discovery in the July 10th issue of Astrophysical Journal Letters.

The Baby Boom galaxy, which belongs to a class of galaxies called starbursts, is the new record holder for the brightest starburst galaxy in the very distant universe, with brightness being a measure of its extreme star-formation rate. It was discovered and characterized using a suite of telescopes operating at different wavelengths. NASA's Hubble Space Telescope and Japan's Subaru Telescope, atop Mauna Kea in Hawaii, first spotted the galaxy in visible-light images, where it appeared as an inconspicuous smudge due to is great distance. 

It wasn't until Spitzer and the James Clerk Maxwell Telescope, also on Mauna Kea in Hawaii, observed the galaxy at infrared and submillimeter wavelengths, respectively, that the galaxy stood out as the brightest of the bunch. This is because it has a huge number of youthful stars. When stars are born, they shine with a lot of ultraviolet light and produce a lot of dust. The dust absorbs the ultraviolet light but, like a car sitting in the sun, it warms up and re-emits light at infrared and submillimeter wavelengths, making the galaxy unusually bright to Spitzer and the James Clerk Maxwell Telescope. 

To learn more about this galaxy's unique youthful glow, Capak and his team followed up with a number of telescopes. They used optical measurements from Keck to determine the exact distance to the galaxy -- a whopping12.3 billion light-years. That's looking back to a time when the universe was 1.3 billion years old (the universe is approximately 13.7 billion years old today).

"If the universe was a human reaching retirement age, it would have been about 6 years old at the time we are seeing this galaxy," said Capak.

The astronomers made measurements at radio wavelengths with the National Science Foundation's Very Large Array in New Mexico. Together with Spitzer and James Clerk Maxwell data, these observations allowed the astronomers to calculate a star-forming rate of about 1,000 to 4,000 stars per year. At that rate, the galaxy needs only 50 million years, not very long on cosmic timescales, to grow into a galaxy equivalent to the most massive ones we see today. 

While galaxies in our nearby universe can produce stars at similarly high rates, the farthest one known before now was about 11.7 billion light-years away, or a time when the universe was 1.9 billion years old. 

"Before now, we had only seen galaxies form stars like this in the teenaged universe, but this galaxy is forming when the universe was only a child," said Capak. "The question now is whether the majority of the very most massive galaxies form very early in the universe like the Baby Boom galaxy, or whether this is an exceptional case. Answering this question will help us determine to what degree the Hierarchical Model of galaxy formation still holds true." 

"The incredible star-formation activity we have observed suggests that we may be witnessing, for the first time, the formation of one of the most massive elliptical galaxies in the universe," said co-author Nick Scoville of Caltech, the principal investigator of the Cosmic Evolution Survey, also known as Cosmos. The Cosmos program is an extensive survey of a large patch of distant galaxies across the full spectrum of light.

"The immediate identification of this galaxy with its extraordinary properties would not have been possible without the full range of observations in this survey," said Scoville.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

-end-

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #8 on: 07/21/2008 08:40 pm »
IMAGE ADVISORY: 2008-138                                                         July 21, 2008

Spitzer Reveals 'No Organics' Zone Around Pinwheel Galaxy

The Pinwheel galaxy is gussied up in infrared light in a new picture from NASA's Spitzer Space Telescope.

The fluffy-looking galaxy, officially named Messier 101, is dominated by a mishmash of spiral arms. In Spitzer's new view, in which infrared light is color coded, the galaxy sports a swirling blue center and a unique, coral-red outer ring.

A new paper appearing July 20 in the Astrophysical Journal explains why this outer ring stands out. According to the authors, the red color highlights a zone where organic molecules called polycyclic aromatic hydrocarbons, which are present throughout most of the galaxy, suddenly disappear.

Polycyclic aromatic hydrocarbons are dusty, carbon-containing molecules found in star nurseries, and on Earth in barbeque pits, exhaust pipes and anywhere combustion reactions take place. Scientists believe this space dust has the potential to be converted into the stuff of life.

"If you were going look for life in Messier 101, you would not want to look at its edges," said Karl Gordon of the Space Telescope Science Institute in Baltimore, Md. "The organics can't survive in these regions, most likely because of high amounts of harsh radiation." To view Spitzer's Pinwheel, visit http://www.nasa.gov/mission_pages/spitzer/multimedia/20080721a.html

The Pinwheel galaxy is located about 27 million light-years away in the constellation Ursa Major. It has one of the highest known gradients of metals (elements heavier than helium) of all nearby galaxies in our universe. In other words, its concentrations of metals are highest at its center, and decline rapidly with distance from the center. This is because stars, which produce metals, are squeezed more tightly into the galaxy's central quarters.

Gordon and his team used Spitzer to learn about the galaxy's gradient of polycyclic aromatic hydrocarbons. The astronomers found that, like the metals, the polycyclic aromatic hydrocarbons decrease in concentration toward the outer portion of the galaxy. But, unlike the metals, these organic molecules quickly drop off and are no longer detected at the very outer rim.

"There's a threshold at the rim of this galaxy, where the organic material is getting destroyed," said Gordon.

The findings also provide a better understanding of the conditions under which the very first stars and galaxies arose. In the early universe, there were not a lot of metals or polycyclic aromatic hydrocarbons around. The outskirt of the Pinwheel galaxy therefore serves as a close-up example of what the environment might look like in a distant galaxy.

In this image, infrared light with a wavelength of 3.6 microns is colored blue; 8-micron light is green; and 24-micron light is red. All three of Spitzer instruments were used in the study: the infrared array camera, the multiband imaging photometer and the infrared spectrograph.

Other authors of the paper include Charles Engelbracht, George Rieke, Karl A. Misselt, J.D. Smith and Robert Kennicutt, Jr. of the University of Arizona, Tucson. Smith is also associated with the University of Toledo, Ohio, and Kennicutt is also associated with the University of Cambridge, England.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. Spitzer's infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Jim Houck of Cornell. The multiband imaging photometer for Spitzer was built by Ball Aerospace Corporation, Boulder, Colo., and the University of Arizona, Tucson. Its principal investigator is George Rieke of the University of Arizona.

 For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #9 on: 10/01/2008 04:18 pm »
Release: 08-85

 

INFRARED ECHOES GIVE NASA’S SPITZER A SUPERNOVA FLASHBACK

 

GREENBELT, Md. -- Hot spots near the shattered remains of an exploded star are echoing the blast's first moments, say scientists using data from NASA’s Spitzer Space Telescope.

 

Eli Dwek of NASA’s Goddard Space Flight Center in Greenbelt, Md. and Richard Arendt of the University of Maryland, Baltimore County, say these echoes are powered by radiation from the supernova shock wave that blew the star apart some 11,000 years ago. "We’re seeing the supernova's first flash," Dwek says.

 

Other Spitzer researchers discovered hot spots near the Cassiopeia A supernova remnant and recognized their importance as light echoes of the original blast. Dwek and Arendt used Spitzer data to probe this hot dust and pin down the cause of the echoes more precisely.

 

Six knots of silicate dust near the remnant show temperatures between -280° and -190° Fahrenheit. Although this might seem frigid by Earthly standards, such temperatures are downright hot compared to typical interstellar dust.

 

Writing in the October 1 issue of The Astrophysical Journal, the scientists show that the only event that could make the grains this hot is the powerful and short-lived pulse of ultraviolet radiation and X-rays that heralded the death of the star. The flash was a hundred billion times brighter than the sun but lasted only a day or so.

 

"They've identified the precise event during the demolition of the star that produces the echo we see," says Michael Werner, the Project Scientist for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

 

Light from the explosion reached Earth in the 17th century, but no one noticed. The Spitzer find gives astronomers a second chance to study the supernova as it unfolds.

 

Although the explosion originally escaped detection, its aftermath -- a hot, expanding gas cloud known as Cassiopeia A (Cas A, for short) -- is one of the best-studied supernova remnants. The blast zone lies 11,000 light-years away in the constellation Cassiopeia.

 

When a massive star runs out of nuclear fuel, its core collapses into a superdense, city-sized object called a neutron star. As the neutron star forms, it stiffens and rebounds. This triggers a mammoth shock wave that blows the star's outer layers to smithereens. The exiting shock creates a high-energy flash that precedes the supernova's rise in visible light.

 

Evidence for a flash associated with this "shock breakout" existed only in computer simulations until January 9, 2008. That's when NASA’s Swift satellite detected a 5-minute-long X-ray pulse from galaxy NGC 2770. A few days later, a new supernova -- designated SN 2008D -- appeared in the galaxy.

 

The infrared echoes from Cas A arise from dust clouds about 160 light-years farther away than the remnant. The supernova’s initial radiation pulse expands through space at the speed of light, then encounters the clouds and heats their dust grains. The dust, in turn, reradiates the energy at infrared wavelengths.

 

The breakout radiation took 160 years to reach the clouds and, once heated, the dust's infrared energy had to make up the same distance. This extra travel time results in a 320-year offset between the supernova's initial outward-moving flash and arrival of the dust's infrared echo at Earth. The researchers plan to use the echoes to paint an intimate portrait of the explosion, the star, and the immediate environment.

 

Light from the Cas A supernova first reached Earth in the late 1600s, but no one back then reported seeing a new star. On August 16, 1680, the English astronomer John Flamsteed might have seen the supernova without recognizing it. He recorded a faint naked-eye star near the position of Cas A, but none exists there now.



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 at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

 

For more information and images related to this release, please visit:

 

http://www.nasa.gov/centers/goddard/news/topstory/2008/spitzer_infrared.html

 

For more information about Spitzer, please visit:

 

http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer
Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #10 on: 10/08/2008 07:43 pm »
Image Advisory: 2008-188                                                       Oct. 8, 2008

Splashy Portrait Helps Explain How Stars Form

Different wavelengths of light swirl together like watercolors in a new, ethereal portrait of a bright, star-forming region.

The multi-wavelength picture combines infrared, visible and X-ray light from NASA's Spitzer Space Telescope, the European Southern Observatory's New Technology Telescope, and the European Space Agency's XMM-Newton orbiting X-Ray telescope, respectively.

The colorful image offers a fresh look at the history of the star-studded region, called NGC 346, revealing new information about how stars form in the universe. NGC 346 is the brightest star-forming region in the Small Magellanic Cloud, a so-called irregular dwarf galaxy that orbits our Milky Way galaxy, 210,000 light-years away.

"NGC 346 is an astronomical zoo," said Dimitrios Gouliermis of the Max Planck Institute for Astronomy in Germany, lead author of a new paper describing the observations in an upcoming issue of the Astrophysical Journal. "When we combined data at various wavelengths, we were able to tease apart what's going on in different parts of the cloud."

The new picture is available online at: http://www.nasa.gov/mission_pages/spitzer/multimedia/20081008.html .

Small stars are scattered throughout the NGC 346 region, while massive stars populate its center. The massive stars and most of the small stars formed at the same time out of one dense cloud, while other small stars were created later through a process called triggered star formation. Intense radiation from massive stars ate away at the surrounding dusty cloud, triggering gas to expand and create shock waves that compressed nearby cold dust and gas into new stars. The red-orange filaments surrounding the center of the image show where this process has occurred.

 

But a set of even younger small stars in the region, seen as a pinkish blob at the top of the image, couldn't be explained by this mechanism. Scientists were scratching their heads over what caused this seemingly isolated group of stars to form.

By combining multi-wavelength data of NGC 346, Gouliermis says he and his team were able to pinpoint the trigger as a very massive star that blasted apart in a supernova explosion about 50,000 years ago. According to the astronomers, this very massive star spurred the isolated young stars into existence before it died, but through a different type of triggered star formation than that which occurred near the center of the region. Fierce winds from the massive star, and not radiation, pushed dust and gas together, compressing it into new stars.

The finding demonstrates that both wind- and radiation-induced triggered star formation are at play in the same cloud. According to Gouliermis, "The result shows us that star formation is a far more complicated process than we used to believe, comprising different competitive or collaborative mechanisms."

The new image also reveals a bubble, seen as a blue halo to the left, caused by the supernova explosion that happened 50,000 years ago. Further analysis shows that this bubble is located within a large expanding gaseous shell, possibly powered by the explosion and the winds of other bright stars in its vicinity.

Infrared light (red) shows cold dust; visible light (green) denotes glowing gas; and X-rays (blue) represent very warm gas. Ordinary stars appear as blue spots with white centers, while young stars enshrouded in dust appear as red spots with white centers.

 

Other authors of this paper include Thomas Henning and Wolfgang Brandner of the Max Planck Institute for Astronomy, and You-Hua Chu and Robert Gruendl of the University of Illinois at Urbana-Champaign.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

More information about Spitzer is at http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

 

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #11 on: 10/14/2008 08:13 am »
NASA's Spitzer Gets Sneak Peak Inside Comet Holmes




When comet Holmes unexpectedly erupted in 2007, professional and amateur astronomers around the world turned their telescopes toward the spectacular event. Their quest was to find out why the comet had suddenly exploded.

Observations taken of the comet after the explosion by NASA's Spitzer Space Telescope deepen the mystery, showing oddly behaving streamers in the shell of dust surrounding the nucleus of the comet. The data also offer a rare look at the material liberated from within the nucleus, and confirm previous findings from NASA's Stardust and Deep Impact missions.

"The data we got from Spitzer do not look like anything we typically see when looking at comets," said Bill Reach of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena, Calif. Reach is lead investigator of the Spitzer observations. "The comet Holmes explosion gave us a rare glimpse at the inside of a comet nucleus." The findings were presented at the 40th meeting of the Division of Planetary Sciences in Ithaca, N.Y.

Every six years, comet 17P/Holmes speeds away from Jupiter and heads inward toward the sun, traveling the same route typically without incident. However, twice in the last 116 years, in November 1892 and October 2007, comet Holmes exploded as it approached the asteroid belt, and brightened a millionfold overnight.

In an attempt to understand these odd occurrences, astronomers pointed NASA's Spitzer Space Telescope at the comet in November 2007 and March 2008. By using Spitzer's infrared spectrograph instrument, Reach was able to gain valuable insights into the composition of Holmes' solid interior. Like a prism spreading visible-light into a rainbow, the spectrograph breaks up infrared light from the comet into its component parts, revealing the fingerprints of various chemicals.

In November of 2007, Reach noticed a lot of fine silicate dust, or crystallized grains smaller than sand, like crushed gems. He noted that this particular observation revealed materials similar to those seen around other comets where grains have been treated violently, including NASA's Deep Impact mission, which smashed a projectile into comet Tempel 1; NASA's Stardust mission, which swept particles from comet Wild 2 into a collector at 13,000 miles per hour (21,000 kilometers per hour), and the outburst of comet Hale-Bopp in 1995.

"Comet dust is very sensitive, meaning that the grains are very easily destroyed, said Reach. "We think the fine silicates are produced in these violent events by the destruction of larger particles originating inside the comet nucleus."

When Spitzer observed the same portion of the comet again in March 2008, the fine-grained silicate dust was gone and only larger particles were present. "The March observation tells us that there is a very small window for studying composition of comet dust after a violent event like comet Holmes' outburst," said Reach.

Comet Holmes not only has unusual dusty components, it also does not look like a typical comet. According to Jeremie Vaubaillon, a colleague of Reach's at Caltech, pictures snapped from the ground shortly after the outburst revealed streamers in the shell of dust surrounding the comet. Scientists suspect they were produced after the explosion by fragments escaping the comet's nucleus.

In November 2007, the streamers pointed away from the sun, which seemed natural because scientists believed that radiation from the sun was pushing these fragments straight back. However, when Spitzer imaged the same streamers in March 2008, they were surprised to find them still pointing in the same direction as five months before, even though the comet had moved and sunlight was arriving from a different location. "We have never seen anything like this in a comet before. The extended shape still needs to be fully understood," said Vaubaillon.

He notes that the shell surrounding the comet also acts peculiarly. The shape of the shell did not change as expected from November 2007 to March 2008. Vaubaillon said this is because the dust grains seen in March 2008 are relatively large, approximately one millimeter in size, and thus harder to move.

"If the shell was comprised of smaller dust grains, it would have changed as the orientation of the sun changes with time," said Vaubaillon. "This Spitzer image is very unique. No other telescope has seen comet Holmes in this much detail, five months after the explosion."

"Like people, all comets are a little different. We've been studying comets for hundreds of years -- 116 years in the case of comet Holmes -- but still do not really understand them," said Reach. "However, with the Spitzer observations and data from other telescopes, we are getting closer."

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

-end-

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #12 on: 10/27/2008 04:37 pm »
NEWS RELEASE: 2008-197                                                                          Oct. 27, 2008

Closest Planetary System Hosts Two Asteroid Belts

New observations from NASA's Spitzer Space Telescope indicate that the nearest planetary system to our own has two asteroid belts. Our own solar system has just one.

The star at the center of the nearby system, called Epsilon Eridani, is a younger, slightly cooler and fainter version of the sun. Previously, astronomers had uncovered evidence for two possible planets in the system, and for a broad, outer ring of icy comets similar to our own Kuiper Belt.

Now, Spitzer has discovered that the system also has dual asteroid belts. One sits at approximately the same position as the one in our solar system. The second, denser belt, most likely also populated by asteroids, lies between the first belt and the comet ring. The presence of the asteroid belts implies additional planets in the Epsilon Eridani system.

"This system probably looks a lot like ours did when life first took root on Earth," said Dana Backman, an astronomer at the SETI Institute, in Mountain View, Calif., and outreach director for NASA's Sofia mission. "The main difference we know of so far is that it has an additional ring of leftover planet construction material." Backman is lead author of a paper about the findings to appear Jan. 10 in the Astrophysical Journal.

Asteroid belts are rocky and metallic debris left over from the early stages of planet formation. Their presence around other stars signals that rocky planets like Earth could be orbiting in the system's inner regions, with massive gas planets circling near the belts' rims. In our own solar system, for example, there is evidence that Jupiter, which lies just beyond our asteroid belt, caused the asteroid belt to form long ago by stirring up material that would have otherwise coalesced into a planet. Nowadays, Jupiter helps keep our asteroid belt confined to a ring.

Astronomers have detected stars with signs of multiple belts of material before, but Epsilon Eridani is closer to Earth and more like our sun overall. It is 10 light-years away, slightly less massive than the sun, and roughly 800 million years old, or one-fifth the age of the sun.

Because the star is so close and similar to the sun, it is a popular locale in science fiction. The television series Star Trek and Babylon 5 referenced Epsilon Eridani, and it has been featured in novels by Issac Asimov and Frank Herbert, among others.

The popular star was also one of the first to be searched for signs of advanced alien civilizations using radio telescopes in 1960. At that time, astronomers did not know of the star's young age.

Spitzer observed Epsilon Eridani with both of its infrared cameras and its infrared spectrometer. When asteroid and comets collide or evaporate, they release tiny particles of dust that give off heat, which Spitzer can see. "Because the system is so close to us, Spitzer can really pick out details in the dust, giving us a good look at the system's architecture," said co-author Karl Stapelfeldt of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The asteroid belts detected by Spitzer orbit at distances of approximately 3 and 20 astronomical units from the star (an astronomical unit is the average distance between Earth and the sun). For reference, our own asteroid belt lies at about 3 astronomical units from the sun, and Uranus is roughly 19 astronomical units away.

One of the two possible planets previously identified around Epsilon Eridani, called Epsilon Eridani, was discovered in 2000. The planet is thought to orbit at an average distance of 3.4 astronomical units from the star -- just outside the innermost asteroid belt identified by Spitzer. This is the first time that an asteroid belt and a planet beyond our solar system have been found in a similar arrangement as our asteroid belt and Jupiter.

Some researchers had reported that Epsilon Eridani b orbits in an exaggerated ellipse ranging between 1 and 5 astronomical units, but this means the planet would cross, and quickly disrupt, the newfound asteroid belt. Instead, Backman and colleagues argue that this planet must have a more circular orbit that keeps it just outside the belt.

The other candidate planet was first proposed in 1998 to explain lumpiness observed in the star's outer comet ring. It is thought to lie near the inner edge of the ring, which orbits between 35 and 90 astronomical units from Epsilon Eridani.

The intermediate belt detected by Spitzer suggests that a third planet could be responsible for creating and shepherding its material. This planet would orbit at approximately 20 astronomical units and lie between the other two planets. "Detailed studies of the dust belts in other planetary systems are telling us a great deal about their complex structure," said Michael Werner, co-author of the study and project scientist for Spitzer at JPL. "It seems that no two planetary systems are alike."

JPL manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. More information about Spitzer is at http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer . More information about extrasolar planets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov .

 

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #13 on: 12/08/2008 06:34 pm »
IMAGE ADVISORY: 2008-228                                             
Dec. 8, 2008

Rivers of Gas Flow Around Stars in New Space Image

A new image from NASA's Spitzer Space Telescope shows a turbulent star-forming region, where rivers of gas and stellar winds are eroding thickets of dusty material.

The picture provides some of the best examples yet of the ripples of gas, or bow shocks, that can form around stars in choppy cosmic waters.

"The stars are like rocks in a rushing river," said Matt Povich of the University of Wisconsin, Madison. "Powerful winds from the most massive stars at the center of the cloud produce a large flow of expanding gas. This gas then piles up with dust in front of winds from other massive stars that are pushing back against the flow." Povich is lead author of a paper describing the new findings in the Dec. 10 issue of the Astrophysical Journal.

Spitzer's new infrared view of the stormy region, called M17, or the Swan nebula, is online at http://www.nasa.gov/mission_pages/spitzer/multimedia/20081208.html . The Swan is located about 6,000 light-years away in the constellation Sagittarius.

Dominating the center of the Swan is a group of massive stars, some exceeding 40 times the mass of our sun. These central stars are 100,000 to one million times as bright as the sun, and roar with radiation and fierce winds made of charged particles that speed along at up to 7.2 kilometers per hour (4.5 million miles per hour). Both the wind and radiation carve out a deep cavity at the center of the picture -- an ongoing process thought to trigger the birth of new stars.

The growth of this cavity pushes gas up against winds from other massive stars, causing "smiley-faced" bow shocks -- three of which can be seen in the new picture. The direction of the bow shocks tells researchers exactly which way the "wind is blowing."

"The bow shocks are like interstellar weather vanes, indicating the direction of the stellar winds in the nebula," said Povich.

Povich and his colleagues also used Spitzer to take an infrared picture of a star-forming region called RCW 49. Both photographs are described in the same Astrophysical Journal paper, and both provide the first examples of multiple bow shocks around the massive stars of star-forming regions.

Spitzer was able to spot the bow shocks because its infrared eyes can pierce intervening dust, and because it can photograph large swaths of sky quickly.

Ultimately, the new observations will help researchers understand how solar systems like our own are able to form and persist in the rough, celestial seas of space.

"The gas being lit up in these star-forming regions looks very wispy and fragile, but looks can be deceiving," said co-author Robert Benjamin of the University of Wisconsin, Whitewater. "These bow shocks serve as a reminder that stars aren't born in quiet nurseries but in violent regions buffeted by winds more powerful than anything we see on Earth."

Other authors include Barbara A. Whitney of the Space Science Institute, Boulder, Colo.; Brian L. Babler, Marilyn R. Meade and Ed Churchwell of the University of Wisconsin, Madison; and Remy Indebetouw of the University of Virginia, Charlottesville.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's 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 .

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #14 on: 01/06/2009 09:35 am »
NEWS RELEASE: 2009-001                                                 Jan. 5, 2009


Dead Stars Tell Story of Planet Birth


PASADENA, Calif. -- Astronomers have turned to an unexpected place to study the evolution of planets -- dead stars.


Observations made with NASA's Spitzer Space Telescope reveal six dead "white dwarf" stars littered with the remains of shredded asteroids. This might sound pretty bleak, but it turns out the chewed-up asteroids are teaching astronomers about the building materials of planets around other stars.


So far, the results suggest that the same materials that make up Earth and our solar system's other rocky bodies could be common in the universe. If the materials are common, then rocky planets could be, too.


"If you ground up our asteroids and rocky planets, you would get the same type of dust we are seeing in these star systems," said Michael Jura of the University of California, Los Angeles, who presented the results today at the American Astronomical Society meeting in Long Beach, Calif. "This tells us that the stars have asteroids like ours -- and therefore could also have rocky planets." Jura is the lead author of a paper on the findings accepted for publication in the Astronomical Journal.


Asteroids and planets form out of dusty material that swirls around young stars. The dust sticks together, forming clumps and eventually full-grown planets. Asteroids are the leftover debris. When a star like our sun nears the end of its life, it puffs up into a red giant that consumes its innermost planets, while jostling the orbits of remaining asteroids and outer planets. As the star continues to die, it blows off its outer layers and shrinks down into a skeleton of its former self -- a white dwarf.


Sometimes, a jostled asteroid wanders too close to a white dwarf and meets its demise -- the gravity of the white dwarf shreds the asteroid to pieces. A similar thing happened to Comet Shoemaker Levy 9 when Jupiter's gravity tore it up, before the comet ultimately smashed into the planet in 1994.


Spitzer observed shredded asteroid pieces around white dwarfs with its infrared spectrograph, an instrument that breaks light apart into a rainbow of wavelengths, revealing imprints of chemicals. Previously, Spitzer analyzed the asteroid dust around two so-called polluted white dwarfs; the new observations bring the total to eight.


"Now, we've got a bigger sample of these polluted white dwarfs, so we know these types of events are not extremely rare," said Jura.


In all eight systems observed, Spitzer found that the dust contains a glassy silicate mineral similar to olivine and commonly found on Earth. "This is one clue that the rocky material around these stars has evolved very much like our own," said Jura.


The Spitzer data also suggest there is no carbon in the rocky debris -- again like the asteroids and rocky planets in our solar system, which have relatively little carbon.


A single asteroid is thought to have broken apart within the last million years or so in each of the eight white-dwarf systems. The biggest of the bunch was once about 200 kilometers (124 miles) in diameter, a bit larger than Los Angeles County.


Jura says the real power of observing these white dwarf systems is still to come. When an asteroid "bites the dust" around a dead star, it breaks into very tiny pieces. Asteroid dust around living stars, by contrast, is made of larger particles. By continuing to use spectrographs to analyze the visible light from this fine dust, astronomers will be able to see exquisite details -- including information about what elements are present and in what abundance. This will reveal much more about how other star systems sort and process their planetary materials.


"It's as if the white dwarfs separate the dust apart for us," said Jura.


Other authors are Ben Zuckerman at the University of California, Los Angeles, and Jay Farihi at Leicester University, England.


This research was funded by NASA and the National Science Foundation. 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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Jacques :-)

Offline MartianBase

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Re: NASA - Spitzer Updates
« Reply #15 on: 01/15/2009 01:03 pm »
Glow of 'hot Jupiters' spotted from Earth for first time

http://www.newscientist.com/article/dn16420-glow-of-hot-jupiters-spotted-from-earth-for-first-time.html

Quote
The glow of 'hot Jupiter' planets has been detected with ground-based telescopes for the first time.

The detections are just a first step, astronomers say. But the advance could help settle a mystery over why some of the massive, close-in planets are scorchingly hot on one half and fairly cool on the other, while others seem to spread their heat more evenly.

More than 300 planets have been found orbiting other stars. Most are gas giants that circle their host stars so closely that they cannot be imaged directly, since the little starlight they do reflect gets lost in the glare of their host stars.

But the heat from some of these planets has previously been measured by NASA's Spitzer Space Telescope.

Spitzer used its heat-sensing infrared instruments to image a star with a planet at its side and then again with the planet hidden behind it. Then astronomers subtracted one from the other to distinguish the planet's heat from that of its star
« Last Edit: 01/15/2009 01:05 pm by MartianBase »

Offline jacqmans

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Re: NASA - Spitzer Updates
« Reply #16 on: 03/12/2009 03:30 pm »
March 12, 2009

 


Galactic Dust Bunnies Found to Contain Carbon After All

Using NASA's Spitzer Space Telescope, researchers have found evidence suggesting that stars rich in carbon complex molecules may form at the center of our Milky Way galaxy.

This discovery is significant because it adds to our knowledge of how stars form heavy elements -- like oxygen, carbon and iron -- and then blow them out across the universe, making it possible for life to develop.

Astronomers have long been baffled by a strange phenomenon: Why have their telescopes never detected carbon-rich stars at the center of our galaxy even though they have found these stars in other places? Now, by using Spitzer's powerful infrared detectors, a research team has found the elusive carbon stars in the galactic center.

"The dust surrounding the stars emits very strongly at infrared wavelengths," says Pedro García-Lario, a research team member who is on the faculty of the European Space Astronomy Center, the European Space Agency's center for space science. He co-authored a paper on this subject in the February 2009 issue of the journal Astronomy & Astrophysics.

"With the help of Spitzer spectra, we can easily determine whether the material returned by the stars to the interstellar medium is oxygen-rich or carbon-rich."

The team of scientists analyzed the light emitted from 40 planetary nebulae – blobs of dust and gas surrounding stars -- using Spitzer's infrared spectrograph. They analyzed 26 nebulae toward the center of the Milky Way -- a region called the "Galactic Bulge" -- and 14 nebulae in other parts of the galaxy. The scientists found a large amount of crystalline silicates and polycyclic aromatic hydrocarbons, two substances that indicate the presence of oxygen and carbon.

This combination is unusual. In the Milky Way, dust that combines both oxygen and carbon is rare and is usually only found surrounding a binary system of stars. The research team, however, found that the presence of the carbon-oxygen dust in the Galactic Bulge seems to be suggestive of a recent change of chemistry experienced by the star.

The scientists hypothesize that as the central star of a planetary nebula ages and dies, its heavier elements do not make their way to the star's outer layers, as they do in other stars. Only in the last moments of the central star's life, when it expands and then violently expels almost all of its remaining outer gasses, does the carbon become detectable. That's when astronomers see it in the nebula surrounding the star.

"The carbon produced through these recurrent 'thermal pulses' is very inefficiently dredged up to the surface of the star, contrary to what is observed in low-metallicity, galactic disk stars," said García-Lario. "It only becomes visible when the star is about to die."

This study supports a hypothesis about why the carbon in some stars does not make its way to the stars' surfaces. Scientists believe that small stars -- those with masses up to one-and-a-half times that of our sun -- that contain lots of metal do not bring carbon to their surfaces as they age. Stars in the Galactic Bulge tend to have more metals than other stars, so the Spitzer data support this commonly held hypothesis. Before the Spitzer study, this hypothesis had never been supported by observation.

This aging and expelling process is typical of all stars. As stars age and die, they burn progressively heavier and heavier elements, beginning with hydrogen and ending with iron. Towards the end of their lives, some stars become what are called "red giants." These dying stars swell so large that if one of them were placed in our solar system, where the sun is now, its outermost border would touch Earth's orbit. As these stars pulsate – losing mass in the process – and then contract, they spew out almost all of their heavier elements. These elements are the building blocks of all planets, including our own Earth (as well as of human beings and any other life forms that may exist in the universe).

The paper is co-authored by José Vicente Perea-Calderón of the European Space Astronomy Center in Villanueva de la Cañada, Spain; Domingo Anibal García-Hernández of the Instituto de Astrofísica de Canarias, on Spain's Tenerife island; Ryszard Szczerba of the Nicolaus Copernicus Astronomical Center in Torun, Poland; and Matt Bobrowsky of the University of Maryland, College Park.

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 Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Jacques :-)

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Re: NASA - Spitzer Updates
« Reply #17 on: 03/12/2009 03:51 pm »
The helium onboard is going to run out someday this spring. Any bets when?

April, 18th.

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Re: NASA - Spitzer Updates
« Reply #18 on: 03/12/2009 08:46 pm »
I'm not familiar with the helium system... pressurizing agent? That would mean loss of thrusters? Given its heliocentric orbit, could it mantain orientation by reaction wheels only?

Apparently it has just recovered from an anomaly a few days ago...

EDIT: Ok, I've just learned helium is in liquid state for cooling the infrared sensors. So running out of helium is indeed not good... well, at least Herschel will take its place :)
« Last Edit: 03/12/2009 08:47 pm by eeergo »
-DaviD-

Offline iamlucky13

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Re: NASA - Spitzer Updates
« Reply #19 on: 03/13/2009 01:09 am »
EDIT: Ok, I've just learned helium is in liquid state for cooling the infrared sensors. So running out of helium is indeed not good... well, at least Herschel will take its place :)

Right...it was always known that Spitzer's life would be limited by it's helium supply. There's some talk of continuing it's use in a limited capacity once it can't maintain cryogenic temperatures anymore, but I don't think any definite steps have been made towards that.

Unfortunately, Herschel's range of 55 to 625 micrometers is generally longer than Spitzers of 3.6 to 160 micrometers, but that's good too, since it will be exploring a new spectral range in high detail, and JWST will pick up the shorter end of Spitzer's range when it comes online.

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