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Ancient supernova seen in a new light

RCW 86

This is all that remains of a supernova explosion that was seen by Chinese astronomers in the year 185 CE. The remnant gas cloud is called RCW 86, and is approximately 8,000 light-years from Earth.

A TWISTED AND TANGLED GAS CLOUD is all that remains of the oldest documented example of a supernova, called RCW 86.

Chinese stargazers witnessed the event in 185 CE, documenting a mysterious ‘guest star’ that remained in the sky for eight months.

The image combines data from four different space telescopes to create a multi-wavelength view.

X-ray images from the European Space Agency’s XMM-Newton Observatory and NASA’s Chandra X-ray Observatory are combined to form the blue and green colours in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova.

Infrared data from NASA’s Spitzer Space Telescope, as well as NASA’s Wide-Field Infrared Survey Explorer (WISE) are shown in yellow and red, and reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy.

By studying the X-ray and infrared data together, astronomers were able to determine that the cause of the explosion witnessed nearly 2,000 years ago was a Type Ia supernova, in which an otherwise-stable white dwarf, or dead star, was pushed beyond the brink of stability when a companion star dumped material onto it.

Furthermore, scientists used the data to solve another mystery surrounding the remnant—how it got to be so big in such a short amount of time.

By blowing out a ‘wind’ prior to exploding, the white dwarf was able to clear out a huge ‘cavity,’ a region of very low-density surrounding the system. The explosion was able to expand into this cavity much faster than it otherwise would have.

RCW 86 is approximately 8,000 light-years away.

Adapted from information issued by NASA / JPL-Caltech / B. Williams (NCSU).

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Runaway star shocks the neighbours

WISE view of Zeta Ophiuchi

The star Zeta Ophiuchi (image centre) is surrounded by a cloud of dust and gas in this view from NASA's WISE infrared space telescope. The star is zooming from right to left at 87,000 kilometres per hour, forming a bow shock in the cloud in front of it.

THE BLUE STAR NEAR THE CENTRE of this image is called Zeta Ophiuchi. When seen at visible light wavelengths it looks like a relatively dim red star surrounded by other dim stars and no dust.

However, in this infrared image taken with NASA’s Wide-field Infrared Survey Explorer, or WISE, a completely different view emerges.

Zeta Ophiuchi is actually a very massive, hot, bright blue star ploughing its way through a large cloud of interstellar dust and gas.

Astronomers think this stellar juggernaut was once part of a binary star system with an even more massive partner. It’s believed that when the partner exploded as a supernova, blasting away most of its mass, Zeta Ophiuchi was suddenly freed from its partner’s pull and shot away like a bullet, moving 24 kilometres per second (87,000 kilometres per hour).

Zeta Ophiuchi is about 20 times more massive and 65,000 times more luminous than the Sun. If it weren’t surrounded by so much dust, it would be one of the brightest stars in the sky and appear blue to the eye.

Like all stars with this kind of extreme mass and power, it subscribes to the ‘live fast, die young’ motto. It’s already about halfway through its very short 8-million-year lifespan.

Artist's impression of WISE

Artist's impression of NASA's WISE space telescope, which studies the cosmos at infrared wavelengths.

In comparison, the Sun is roughly halfway through its 10-billion-year lifespan.

While the Sun will eventually become a quiet white dwarf, Zeta Ophiuchi, like its ex-partner, will ultimately die in a massive explosion called a supernova.

Perhaps the most interesting features in this image are related to the interstellar gas and dust that surrounds Zeta Ophiuchi. Off to the sides of the image and in the background are relatively calm clouds of dust, appearing green and wispy.

Near Zeta Ophiuchi, these clouds look quite different. The cloud in all directions around the star is brighter and redder, because the extreme amounts of ultraviolet radiation emitted by the star are heating the cloud, causing it to glow more brightly in the infrared than usual.

Even more striking, however, is the bright yellow curved feature directly above Zeta Ophiuchi. This is a magnificent example of a bow shock. The runaway star is flying from the lower right towards the upper left. As it does so, its very powerful stellar wind is pushing the gas and dust out of its way, forming an invisible ‘bubble’ all around it.

Directly in front of the star’s path the wind is compressing the gas together so much that it makes it glow extremely brightly (in the infrared).

Adapted from information issued by NASA / JPL-Caltech / UCLA / IPAC.

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Orion’s hidden dimensions

WISE view of part of Orion

An infrared view of the region around The Hunter's head in the constellation Orion, taken by NASA's WISE infrared space telescope. The bright star at lower left is Betelguese.

IN GREEK MYTHOLOGY, Orion was a hunter whose vanity was so great that he angered the goddess Artemis. As his punishment, Artemis banished the hunter to the sky where he can be seen as the famous constellation Orion.

In the constellation, Orion’s head is represented by the star Lambda Orionis. When viewed in infrared light, NASA’s Wide-field Infrared Survey Explorer, or WISE, reveals a giant nebula around Lambda Orionis, inflating Orion’s head to huge proportions.

Lambda Orionis (1,060 light-years from Earth) is a hot, massive star that is surrounded by several other hot, massive stars, all of which are creating radiation that excites a ring of dust, creating the ‘Lambda Orionis molecular ring’.

Also known as SH 2-264, the Lambda Orionis molecular ring is sometimes called the Meissa ring. In Arabic, the star Lambda Orionis is known as ‘Meissa’ or ‘Al-Maisan,’ meaning ‘the shining one’. It is 1,470 light-years from Earth.

The Meissa Ring is of interest to astronomers because it contains clusters of young stars and proto-stars, or forming stars, embedded within the clouds.

With a diameter of approximately 130 light-years, the Lambda Orionis molecular ring is notable for being one of the largest star-forming regions WISE has seen.

This is also the largest single image featured by WISE so far, with an area of the sky approximately 10 by 10 degrees in size; equivalent to a grid of 20 by 20 full Moons.  Nevertheless, at less than 1 percent of the whole sky’s area, it is just a taste of WISE data.

Close up WISE view of Betelguese

Betelgeuse is a red supergiant star, approximately 600 light-years from Earth. It looks blue in this infrared view.

The Hunter’s female warrior friend

The bright blue star in the lower left corner of the image is Betelgeuse, which represents one shoulder of the hunter Orion. The name Betelgeuse is actually a corruption of the original Arabic phrase ‘Yad al-Jauza’ meaning ‘hand of the giant one’.

Betelgeuse (roughly 600 light-years from Earth) is well known for being a red supergiant star, yet in WISE’s infrared view it appears blue, as do most stars in WISE images. This is because most stars, including Betelgeuse, put out more light in the shortest infrared wavelengths of light captured by WISE, and those shorter wavelengths are presented in WISE images as blue and cyan.

In visible light, Orion’s other shoulder is clearly marked by the variable star Bellatrix (400 light-years from Earth). In infrared light, however, Bellatrix is a somewhat unremarkable cyan-coloured star in the right side of the image.

In Latin, Bellatrix means ‘female warrior,’ which is perhaps why the name was chosen for a female witch character in the popular Harry Potter books.

Also seen in this image are two dark nebulae, Barnard 30 and Barnard 35, which are parts of the Meissa ring that are so dense they block out visible light. Barnard 30 is the bright knob of gas and dust in the top centre part of the image. Barnard 35 appears as a hook extending towards the centre of the ring just above and to the right of the star Betelgeuse.

The bright reddish object seen to in the middle right part of the image is the star HR 1763, which is surrounded by another star-forming region, LBN 876.

Download a full-size (1.83M, 1600 x 1489 pixel) image here.

Adapted from information issued by NASA / JPL-Caltech / WISE Team.

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Celestial treasure trove

WISE image of the Andromeda galaxy

WISE's infrared view of the Andromeda galaxy ignores most of the stars, and instead brings out detail in dust clouds heated by the energy of stars.

  • WISE space telescope studied the cosmos at infrared wavelengths
  • It took 2.7 million images during its mission
  • Huge archive of images and data has now been released

ASTRONOMERS ARE SIFTING through hundreds of millions of galaxies, stars and asteroids collected in the first bundle of data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission.

WISE launched into space on December 14, 2009, on a mission to map the entire sky in infrared light with greatly improved sensitivity and resolution over its predecessors.

From its orbit, it scanned the skies about one-and-a-half times while collecting images taken at four infrared wavelengths of light. It took more than 2.7 million images over the course of its mission, capturing objects ranging from faraway galaxies to asteroids relatively close to Earth.

Like other infrared telescopes, WISE required coolant to chill its heat-sensitive detectors. When this frozen hydrogen coolant ran out, as expected, in early October, 2010, two of its four infrared channels were still operational.

The survey was then extended for four more months, with the goal of finishing its sweep for asteroids and comets in the main asteroid belt of our Solar System.

The satellite went into hibernation in early February of this year.

WISE image of IC 342

Spiral galaxy IC 342 is normally hard to see through the stars of the Milky Way, but WISE's infrared eyes can see it spectacular detail.

WISE image Rho Ophiuchi

The Rho Ophiuchi cloud complex is one of the nearest star-forming regions to Earth. WISE's infrared capabilities enable astronomers to see normally hidden details.

The mission’s nearby discoveries included 20 comets, more than 33,000 asteroids between Mars and Jupiter, and 133 near-Earth objects, which are those asteroids and comets with orbits that come close to Earth’s path around the Sun.

Data from the first 57 percent of the sky surveyed is now accessible through an online public archive. The complete survey, with improved data processing, will be made available in the spring of 2012.

A predecessor to WISE, the Infrared Astronomical Satellite, served a similar role about 25 years ago, and those data are still valuable to astronomers today. Likewise, the WISE legacy is expected to endure for decades.

Astronomers will use WISE’s infrared data to hunt for hidden oddities, and to study trends in large populations of known objects. Survey missions often result in the unexpected discoveries too, because they are looking everywhere in the sky rather than at known targets.

The whole collection can be seen at: http://wise.ssl.berkeley.edu/gallery_images.html

Adapted from information issued by JPL.

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WISE eyes on the sky

WISE image of the Pleiades star cluster

This image shows the famous Pleiades cluster of stars as seen through the eyes of WISE, or NASA's Wide-field Infrared Survey Explorer. The mosaic contains a few hundred image frames—just a fraction of the more than one million WISE has captured so far as it completes its first survey of the entire sky in infrared light.

  • Infrared mapping telescope completes all-sky survey
  • Over 1 million images in total, with more to come
  • Spotted 100,000+ asteroids, and discovers a dozen comets

NASA’s Wide-field Infrared Survey Explorer, or WISE, completed its first survey of the entire sky on July 17. The mission has generated more than 1 million images so far, of everything from asteroids to distant galaxies.

“Like a globe-trotting shutterbug, WISE has completed a world tour with 1.3 million slides covering the whole sky,” said Edward Wright, the principal investigator of the mission at the University of California, Los Angeles.

Some of the images have been processed and stitched together into a new picture just released. It shows the Pleiades cluster of stars, also known as the Seven Sisters, resting in a tangled bed of wispy dust.

The pictured region covers seven square degrees, or an area equivalent to 35 full Moons, highlighting the telescope’s ability to take wide shots of vast regions of space.

WISE all-sky infrared map

WISE all-sky map. If you eyes could see infrared instead of normal visible light, this is what the sky would look like.

The new picture was taken in February. It combines infrared light from WISE’s four detectors in a range of wavelengths, and highlights the region’s expansive dust cloud, through which the Seven Sisters and other stars in the cluster are passing. Infrared light also reveals the smaller and cooler stars of the family.

Mapping job almost finished

The mission scanned strips of the sky as it orbited around the Earth’s poles since its launch last December. WISE always stays over the Earth’s day-night line. As the Earth moves around the Sun, new slices of sky come into the telescope’s field of view.

It has taken six months, or the amount of time for Earth to travel halfway around the sun, for the mission to complete one full scan of the entire sky.

For the next three months, the mission will map half of the sky again. This will enhance the telescope’s data, revealing more hidden asteroids, stars and galaxies. The mapping will give astronomers a look at what’s changed in the sky.

The mission will end when the instrument’s block of solid hydrogen coolant, needed to chill its infrared detectors, runs out.

Artist's impression of WISE

Artist's impression of WISE, NASA's Wide-field Infrared Survey Explorer.

“The eyes of WISE have not blinked since launch,” said William Irace, the mission’s project manager at NASA’s Jet Propulsion Laboratory. “Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned.”

Over 100,000 asteroids spotted

So far, WISE has spotted more than 100,000 asteroids, both known and previously unseen. Most of these space rocks are in the main belt between Mars and Jupiter.

However, some are “near-Earth objects”, asteroids and comets with orbits that pass relatively close to Earth. WISE has discovered more than 90 of these new near-Earth objects.

The infrared telescope is also good at spotting comets that orbit far from Earth and has discovered more than a dozen of these so far.

WISE’s infrared vision also gives it a unique ability to pick up the glow of cool stars, called brown dwarfs, in addition to distant galaxies bursting with light and energy. These galaxies are called ultra-luminous infrared galaxies. WISE can see the brightest of them.

Adapted from information issued by NASA / JPL-Caltech / UCLA .

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Space Rock: the latest hits

NASA’s Wide-field Infrared Survey Explorer, or WISE, is busy surveying the landscape of the infrared sky, building up a catalogue of cosmic specimens—everything from distant galaxies to “failed” stars, called brown dwarfs.

Closer to home, the mission is picking out an impressive collection of asteroids and comets, some known and some never seen before. Most of these hang out in the Main Belt between Mars and Jupiter, but a small number are near-Earth objects — asteroids and comets with orbits that pass within about 48 million kilometres (30 million miles) of Earth’s orbit. By studying a small sample of near-Earth objects, WISE will learn more about the population as a whole. How do their sizes differ, and how many objects are dark versus light?

“We are taking a census of a small sample of near-Earth objects to get a better idea of how they vary,” said Amy Mainzer, the principal investigator of NEOWISE, a program to catalogue asteroids seen with WISE.

Adapted from information issued by NASA / JPL-Caltech.

Space telescope reveals hidden cosmos

WISE space telescope image of the Heart and Soul nebulae

Covering an area of the sky over 10 times as wide as the full Moon, the Heart and Soul nebulae form a vast star-forming complex about 6,000 light-years from Earth.

  • Infrared telescope, good for seeing cold objects
  • Making survey of the entire sky
  • Has spotted 60,000 asteroids so far

NASA’s Wide-field Infrared Survey Explorer, or WISE, has captured a huge mosaic of two bubbling clouds in space, known as the Heart and Soul nebulae.

The space telescope, which has completed about 74% of its infrared survey of the entire sky, has already captured nearly one million frames like the ones making up the newly released mosaic.

“This new image demonstrates the power of WISE to capture vast regions,” said Ned Wright, the mission’s principal investigator at UCLA. “We’re looking north, south, east and west to map the whole sky.”

The Heart nebula is named after its resemblance to a human heart; the nearby Soul nebula happens to resemble a heart too, but only the symbolic kind with two lobes.

The nebulae, which are about 6,000 light-years away, are both massive star-making factories, shown by the giant bubbles blown into surrounding dust by the radiation and “winds” from the stars.

The infrared vision of WISE allows it to see into the cooler and dustier crevices of clouds like these, where gas and dust are just beginning to collect into new stars.

The new image was captured as WISE circled over Earth’s poles, scanning strips of the sky. It is stitched together from 1,147 frames, taken with a total exposure time of three-and-a-half hours.

An artist's impression of the WISE space telescope

WISE carries an infrared telescope cooled by solid hydrogen.

WISE will complete its first map of the sky in July 2010. It will then spend the next three months surveying much of the sky a second time, before the solid-hydrogen coolant needed to chill its infrared detectors runs dry.

The first public instalment of the WISE catalogue will be released in summer 2011.

About 960,000 WISE images have been beamed down from space to date. Some show ethereal star-forming clouds, while others reveal the ancient light of very remote, powerful galaxies.

The Solar System’s rocky rubble

Many of the WISE images are speckled with little dots … asteroids in our Solar System. So far, the mission has seen more than 60,000 asteroids, most of which lie in the main belt between Mars and Jupiter.

About 11,000 of these objects are newly discovered, and about 50 of them belong to a class of near-Earth objects, which have paths that take them within about 48 million kilometres (30 million miles) of Earth’s orbit.

One goal of the WISE mission is to study asteroids throughout our Solar System and to find out more about how they vary in size and composition. Infrared helps with this task because it can get better size measurements of the space rocks than visible light.

“Infrared will help us understand more about the sizes, properties, and origins of asteroids near and far,” said Amy Mainzer, the principal investigator of NEOWISE, a program to study and catalogue asteroids seen by WISE (the acronym comes from combining near-Earth object, or NEO, with WISE).

WISE will also study the Trojans, asteroids that run along with Jupiter in its orbit around the Sun in two packs — one in front of and one behind the gas giant planet. It has seen more than 800 of these objects, and by the end of the mission, should have observed about half of all 4,500 known Trojans. The results will influence competing concepts about how the outer planets evolved.

Comets have also made their way into WISE images, with more than 72 seen so far, about a dozen of them new. WISE is taking a census of the types of orbits comets ride in. The data will help explain what kicks comets out of their original, more distant orbits, sending them in toward the Sun.

Adapted from information issued by NASA / JPL-Caltech / UCLA.