Multicoloured view of supernova remnant RCW 86

Credit: ESA/XMM-Newton & NASA/Chandra (X-ray); NASA/WISE/Spitzer (Infrared)

Most celestial events unfold over thousands of years or more, making it impossible to follow their evolution on human timescales.

Supernovas are notable exceptions, the powerful stellar explosions that make stars as bright as an entire galaxy for several days.

Although they are very rare, only a few such explosions take place every century in a typical galaxy, supernovas can be seen with the naked eye if they are reasonably nearby.

In fact, when supernovas were discovered they were thought to be new stars appearing in the sky, 'nova' means new in Latin.

Astronomers have recorded supernovas long before a theoretical understanding of these events as stellar explosions was developed in the 20th century.

The most ancient documented record dates back to 185 AD, when Chinese astronomers saw a 'guest star' that remained visible for several months, in the vicinity of the two stars Alpha and Beta Centauri.

The material ejected during these explosions sweeps up gas and dust from the surroundings, creating picturesque supernova remnants that can be observed long after the explosion.

Modern astronomers believe that the object shown in this image, the supernova remnant RCW 86, is what remains of the supernova that was discovered in 185 AD.

The blue and green glow at the edges of the bubble represents X-ray emission from hot gas, heated to millions of degrees by shock waves generated after the explosion.

The diffuse red glow marks infrared emission from warm dust in the interstellar medium around RCW 86.

Sprinkled across the image, in yellow, are young stars that shine brightly at infrared wavelengths.

This image combines X-ray data from ESA's XMM-Newton and NASA's Chandra X-ray Observatory (combined to form the blue and green colours) with infrared observations from NASA's Spitzer Space Telescope and Wide-Field Infrared Survey Explorer - WISE (yellow and red).

The supernova remnant RCW 86 is some 8000 light-years away.

NASA WISE: Mysteries of 'Interstellar' Space revealed

This enormous mosaic of the Milky Way galaxy from NASA's Wide-field Infrared Survey Explorer (WISE), shows dozens of dense clouds, called nebulae. 

Many nebulae seen here are places where new stars are forming, creating bubble like structures that can be dozens to hundreds of light-years in size.

Image Credit: NASA

The new Paramount film "Interstellar" imagines a future where astronauts must find a new planet suitable for human life after climate change destroys the Earth's ability to sustain us.

Multiple NASA missions are helping avoid this dystopian future by providing critical data necessary to protect Earth.

Yet the cosmos beckons us to explore farther from home, expanding human presence deeper into the solar system and beyond.

For thousands of years we've wondered if we could find another home among the stars. We're right on the cusp of answering that question.

If you step outside on a very dark night you may be lucky enough to see many of the 2,000 stars visible to the human eye.

They're but a fraction of the billions of stars in our galaxy and the innumerable galaxies surrounding us.

Multiple NASA missions are helping us extend humanity's senses and capture starlight to help us better understand our place in the universe.

Largely visible light telescopes like Hubble show us the ancient light permeating the cosmos, leading to groundbreaking discoveries like the accelerating expansion of the universe.

Through infrared missions like Spitzer, SOFIA and WISE, we've peered deeply through cosmic dust, into stellar nurseries where gases form new stars.

With missions like Chandra, Fermi and NuSTAR, we've detected the death throes of massive stars, which can release enormous energy through supernovas and form the exotic phenomenon of black holes.

Yet it was only in the last few years that we could fully grasp how many other planets there might be beyond our solar system.

Some 64 million miles (104 kilometers) from Earth, the Kepler Space Telescope stared at a small window of the sky for four years.

As planets passed in front of a star in Kepler's line of view, the spacecraft measured the change in brightness.

Kepler was designed to determine the likelihood that other planets orbit stars. Because of the mission, we now know it's possible every star has at least one planet.

Solar systems surround us in our galaxy and are strewn throughout the myriad galaxies we see.

Though we have not yet found a planet exactly like Earth, the implications of the Kepler findings are staggering, there may very well be many worlds much like our own for future generations to explore.

NASA also is developing its next exoplanet mission, the Transiting Exoplanet Survey Satellite (TESS), which will search 200,000 nearby stars for the presence of Earth-size planets.



The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky.

In a two-year survey of the solar neighbourhood, TESS will monitor more than 500,000 stars for temporary drops in brightness caused by planetary transits.

This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat.

Wide-Field Infrared Survey Explorer (WISE) Image: Southern constellation of Circinus

Credit: NASA/JPL-Caltech/UCLA

The Wide-Field Infrared Survey Explorer (WISE), has uncovered a striking population of young stellar objects in a complex of dense, dark clouds in the southern constellation of Circinus.

This mosaic from WISE covers an area on the sky so large that it could contain a grid of 11 by 7 full moons.

The cloud itself is some 2,280 light-years away and spans more than 180 light-years across.

When an interstellar cloud becomes dense and cool enough, molecules can form in it, so astronomers call these molecular clouds.

Molecular clouds are where stars first form, and astronomers study them hoping to learn about the earliest stages in the lives of stars.

These clouds are so dense that the dust within blocks visible wavelengths of light. Telescopes that see visible light only detect ghostly dark patches in the sky, called dark nebulae.

Constellation of Circinus. Visible in the southern hemisphere and best at mid-evening during June. A small constellation, first defined in the 18th century.

The infrared vision of WISE was able to pierce through the cloud and see the light of the dust itself and newly forming stars within.

The colours used in this image represent specific wavelengths of infrared light.

Blue and cyan represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars.

Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.

In the western part of the cloud (right of the image center) there is a prominent cluster of red-colored sources.

This is light coming from large amounts of warm, concentrated dust. These are what astronomers call young stellar objects, stars so new that they have yet to begin nuclear fusion in their cores and are enveloped by cocoons of dust.

These young stars also power large-scale outflows of gas that are detected by radio telescopes. As these young stars develop, they will emerge from their cocoons and begin to light up their surroundings, making the Circinus cloud shine in visible light.

Also in this image: the brightest star in the upper-right is IRAS 14484-6152, a giant star rich in carbon. The red object to the east (left) of the brightest nebulosity is an O-type star.

It derives its red colour from the surrounding dust, which is being heated by this massive star.

IRAS 14568-6304 is one of several outflow sources in the Circinus-West clump. Together, these sources make up one of the brightest, most massive, and most energetic outflows ever reported.

Scientists have even suggested calling Circinus-West the “nest of molecular outflows” in tribute to this activity.

Hubble IRAS 14568-6304: Violent Birth Announcement from an Infant Star

Image courtesy ESA/Hubble and NASA. Acknowledgements: R. Sahai, NASA JPL/ Serge Meunier. 

This Hubble image shows IRAS 14568-6304, a young star that is cloaked in a haze of golden gas and dust.

It appears to be embedded within an intriguing swoosh of dark sky, which curves through the image and obscures the sky behind.

The Wide-Field Infrared Survey Explorer (WISE), has uncovered a striking population of young stellar objects in a complex of dense, dark clouds in the southern constellation of Circinus.

This dark region is known as the Circinus molecular cloud.

This cloud has a mass around 250 000 times that of the sun, and it is filled with gas, dust and young stars.

Within this cloud lie two prominent and enormous regions known colloquially to astronomers as Circinus-West and Circinus-East.

Each of these clumps has a mass of around 5000 times that of the sun, making them the most prominent star-forming sites in the Circinus cloud.

The clumps are associated with a number of young stellar objects, and IRAS 14568-6304, featured here under a blurry fog of gas within Circinus-West, is one of them.

IRAS 14568-6304 is special because it is driving a protostellar jet, which appears here as the "tail" below the star. This jet is the leftover gas and dust that the star took from its parent cloud to help form it.

While most of this material forms the star and its accretion disc, the disc of material surrounding the star, which may one day form planets, at some point in the formation process the star began to eject some of the material at supersonic speeds through space.

This phenomenon is not only beautiful, but can also provide us with valuable clues about the process of star formation.

NASA WISE study challenges black hole 'doughnut' theory

Active, supermassive black holes at the hearts of galaxies tend to fall into two categories: those that are hidden by dust, and those that are exposed. 

Credit: NASA/JPL-Caltech

A survey of more than 170,000 supermassive black holes, using NASA's Wide-field Infrared Survey Explorer (WISE), has astronomers reexamining a decades-old theory about the varying appearances of these interstellar objects.

The unified theory of active, supermassive black holes, first developed in the late 1970s, was created to explain why black holes, though similar in nature, can look completely different.

Some appear to be shrouded in dust, while others are exposed and easy to see.

The unified model answers this question by proposing that every black hole is surrounded by a dusty, doughnut-shaped structure called a torus.

Depending on how these "doughnuts" are oriented in space, the black holes will take on various appearances.

For example, if the doughnut is positioned so that we see it edge-on, the black hole is hidden from view. If the doughnut is observed from above or below, face-on, the black hole is clearly visible.

However, the new WISE results do not corroborate this theory. The researchers found evidence that something other than a doughnut structure may, in some circumstances, determine whether a black hole is visible or hidden.

The team has not yet determined what this may be, but the results suggest the unified, or doughnut, model does not have all the answers.

"Our finding revealed a new feature about active black holes we never knew before, yet the details remain a mystery," said Lin Yan of NASA's Infrared Processing and Analysis Center (IPAC), based at the California Institute of Technology in Pasadena.

"We hope our work will inspire future studies to better understand these fascinating objects."

Yan is the second author of the research accepted for publication in the Astrophysical Journal.

The lead author is a post-doctoral researcher, Emilio Donoso, who worked with Yan at IPAC and has since moved to the Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE) in Argentina.

The research also was co-authored by Daniel Stern at NASA's Jet Propulsion Laboratory in Pasadena, California, and Roberto Assef of Universidad Diego Portales in Chile and formerly of JPL.

Every galaxy has a massive black hole at its heart. The new study focuses on the "feeding" ones, called active, supermassive black holes, or active galactic nuclei. These black holes gorge on surrounding gas material that fuels their growth.

With the aid of computers, scientists were able to pick out more than 170,000 active supermassive black holes from the WISE data.

They then measured the clustering of the galaxies containing both hidden and exposed black holes—the degree to which the objects clump together across the sky.

More information: The Angular Clustering of WISE-Selected AGN: Different Haloes for Obscured and Unobscured AGN, arxiv.org/abs/1309.2277

NASA WISE Discovers Coldest Brown Dwarf Neighbour of the Sun

This artist's conception shows a newfound object named WISE J085510.83-071442.5, the coldest known brown dwarf. 

Credit: Penn State University/NASA/JPL-Caltech

A brown dwarf as cold as the North Pole has been discovered lurking remarkably close to our solar system, and it appears to be the coldest of its kind yet found, scientists say.

Using NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope, astronomers discovered the dim, "failed star" lurking just 7.2 light-years away, making it the fourth closest system to our sun.

"It's very exciting to discover a new neighbor of our solar system that is so close," Kevin Luhman, an astronomer at Pennsylvania State University's Center for Exoplanets and Habitable Worlds, said in a statement.

"And given its extreme temperature, it should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."

This diagram illustrates the locations of the star systems closest to the sun. 

Credit: Penn State University

Brown dwarfs are sometimes called failed stars because they have many of the elements of that make up stars, but they lack the huge mass needed to kick off nuclear fusion in their core.

As a result, these objects don't radiate starlight and they sometimes resemble planets.

Some are even cool enough to have atmospheres much like gas giants.

While brown dwarfs are hidden in images taken in the visible spectrum, infrared telescopes like WISE can pick up the meager glow of brown dwarfs.

Luhman and colleagues first spotted the object in WISE data. It appeared to be moving quite fast, hinting that it was close by.

The team then investigated the object using Spitzer and the Gemini South telescope on Cerro Pachon in Chile to measure its distance and temperature.

"It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the sun's nearest neighbours," Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

Dubbed WISE J085510.83-071442.5, our newfound neighbor is now the record-holder for the coldest brown dwarf, with a temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13 degrees Celsius), Luhman and colleagues say.

The previous record holders were more tepid, chilling only to room temperature.

At 3 to 10 times the mass of Jupiter, the object also may be one of the least massive brown dwarfs ever found, the astronomers say.

Because it is so small, the scientists say it's possible that the body is actually a planet ejected from its star system, but brown dwarfs are known to be quite common cosmic objects.

The findings were described April 21 in The Astrophysical Journal.

NASA WISE: Uranus and the Planet X myth - debunked

The hunt for Planet X began after Uranus (pictured) was first discovered in 1781 with astrologers hoping it could explain the wobbly orbit of Uranus around the sun

It was an elusive planet that for 200 years appeared to explain Uranus's wobbly orbit and there was the sister sun theorised to be near our solar system that caused asteroids to swerve toward Earth.

There is just one problem: neither "Planet X" nor "Nemesis" ever existed, researchers now say. Although, there is still a trace of doubt.

"The outer solar system probably does not contain a large gas giant planet ("Planet X"), or a small, companion star ("Nemesis")," concluded University of Pennsylvania astronomer Kevin Luhman, who directed the study using NASA's Wide-field Infrared Survey Explorer (WISE) telescope.

The results were published in the most recent edition of The Astrophysical Journal.

Most theories had estimated Planet X to be up to four times the size of Jupiter—the biggest planet in our solar system.

They suggested it would be found some 1,486 billion kilometers (923 billion miles) from the sun, or about 10,000 times farther than the Earth's orbit.

But the images gathered by the telescope did not detect any object larger than Jupiter.

Luhman doesn't rule out the possibility that a planet is lurking somewhere in the asteroid belt.

It would be hard to find if it were closely aligned with a bright star that blinds the telescope or were much smaller than had been theorized.

A computer generated NASA montage obtained 29 August 2002 from images collected by the Voyager 2 spacecraft shows Neptune (Lower-L) as it would appear from a spacecraft approaching Triton, Neptune's largest moon

But after this latest survey, Luhman said the odds of finding one are very unlikely: "That is like a one in a hundred chance."

History of Planet X
Scientists first imagined the existence of Planet X in 1781, when they discovered Uranus, a gas giant that astonished astronomers with its orbital variations, apparently incompatible with Newton's laws of gravity.

Observers concluded that these irregularities could be explained by the existence of another, unknown planet that was exerting its own gravitational force.

Attempts to track this mysterious Planet X led to the discovery of Neptune in 1846. But the estimated mass of Neptune couldn't explain the deviations of Uranus's orbit.

That led astronomers to continue their search for Planet X—which, in turn, led to the discovery of Pluto in 1930. But the dwarf planet was also too small to explain Uranus's irregular path around the sun.

Finally, in the 1990s, researchers determined that they had slightly overestimated the mass of Neptune, which meant the planet could in fact be the reason for Uranus's orbital behaviour.

Yet Planet X believers were still not convinced.

Sister sun killed dinosaurs?
The existence of Nemesis, a sun-like star nearby, was first posited in the 1980s. The star, by occasionally coming closer to the sun, interfered with the orbit of comets and asteroids leading them to occasionally hit the Earth.

Collisions like these are blamed for the five mass extinctions over the last 540 million years—the most recent being the dinosaur extinction 65 million years ago.

"So over the years, there have been different pieces of evidence suggesting there might be something there," Luhman explained to reporters but the WISE telescope didn't find anything.

The hunt for Planet X and Nemesis may have turned up empty, but the study did uncover 3,525 stars and brown dwarfs, celestial objects whose mass puts them between a star and a large planet, within 500 light years of the sun.

"Neighbouring star systems that have been hiding in plain sight just jump out in the WISE data," said Ned Wright, a University of California, Los Angeles astronomer who contributed to the study.

NASA WISE survey finds thousands of new stars, but no 'Planet X'

A nearby star stands out in red in this image from the Second Generation Digitized Sky Survey (DSS). 

Image credit: DSS /NASA/JPL-Caltech

After searching hundreds of millions of objects across our sky, NASA's Wide-Field Infrared Survey Explorer (WISE) has turned up no evidence of the hypothesized celestial body in our solar system commonly dubbed "Planet X."

Researchers previously had theorized about the existence of this large, but unseen celestial body, suspected to lie somewhere beyond the orbit of Pluto.

In addition to "Planet X," the body had garnered other nicknames, including "Nemesis" and "Tyche."

This recent study, which involved an examination of WISE data covering the entire sky in infrared light, found no object the size of Saturn or larger exists out to a distance of 10,000 astronomical units (au), and no object larger than Jupiter exists out to 26,000 au.

One astronomical unit equals 93 million miles. Earth is 1 au, and Pluto about 40 au, from the Sun.

Kevin Luhman

"The outer solar system probably does not contain a large gas giant planet, or a small, companion star," said Kevin Luhman of the Center for Exoplanets and Habitable Worlds at Penn State University, author of a paper 'A SEARCH FOR A DISTANT COMPANION TO THE SUN WITH WISE' in the Astrophysical Journal describing the results.

But searches of the WISE catalogue are not coming up empty. A second study reveals several thousand new residents in our Sun's "backyard," consisting of stars and cool bodies called brown dwarfs.

Ned Wright

"Neighbouring star systems that have been hiding in plain sight just jump out in the WISE data," said Ned Wright of the University of California, Los Angeles (UCLA), the principal investigator of the mission.

WISE survey finds thousands of new stars, but no 'Planet X'

Data from NASA's WISE, has found no evidence for a hypothesized body sometimes referred to as "Planet X." 

Credit: Penn State University

The second WISE study, which concentrated on objects beyond our solar system, found 3,525 stars and brown dwarfs within 500 light-years of our Sun.

Davy Kirkpatrick

"We're finding objects that were totally overlooked before," said Davy Kirkpatrick of NASA's Infrared and Processing Analysis Center (IPAC) at the California Institute of Technology, Pasadena, Calif.

Kirkpatrick is lead author of the second paper, also in the Astrophysical Journal.

Some of these 3,525 objects also were found in the Luhman study, which catalogued 762 objects.

The WISE mission operated from 2010 through early 2011, during which time it performed two full scans of the sky, with essentially a six-month gap between scans.

The survey captured images of nearly 750 million asteroids, stars and galaxies. In November 2013, NASA released data from the AllWISE program, which now enables astronomers to compare the two full-sky surveys to look for moving objects.

In general, the more an object in the WISE images appears to move over time, the closer it is. This visual clue is the same effect at work when one observes a plane flying low to the ground versus the same plane flying at higher altitude.

Though traveling at the same speed, the plane at higher altitude will appear to be moving more slowly.

Searches of the WISE data catalogue for these moving objects are uncovering some of the closest stars.

The discoveries include a star located about 20 light-years away in the constellation Norma, and as reported last March, a pair of brown dwarfs only 6.5 light-years away, making it the closest star system to be discovered in nearly a century.

Despite the large number of new solar neighbors found by WISE, "Planet X" did not show up.

Previous speculations about this hypothesized body stemmed in part from geological studies that suggested a regular timing associated with mass extinctions on Earth.

The idea was that a large planet or small star hidden in the farthest reaches of our solar system might periodically sweep through bands of outer comets, sending them flying toward our planet.

The Planet X-based mass extinction theories were largely ruled out even prior to the new WISE study.

WISE survey finds thousands of new stars, but no 'Planet X'

The third closest Binary star system to the sun, called WISE J104915.57-531906, is at the center of the larger image, which was taken by NASA's WISE. 

Credit: NASA /JPL /Gemini Observatory /AURA /NSF

Other theories based on irregular comet orbits had also postulated a Planet X-type body.

The new WISE study now argues against these theories as well.

Both of the WISE searches were able to find objects the other missed, suggesting many other celestial bodies likely await discovery in the WISE data.

"We think there are even more stars out there left to find with WISE. We don't know our own sun's backyard as well as you might think," said Ned Wright.

WISE was put into hibernation upon completing its primary mission in 2011.

In September 2013, it was reactivated, renamed NEOWISE and assigned a new mission to assist NASA's efforts to identify the population of potentially hazardous near-Earth objects.

NEOWISE will also characterise previously known asteroids and comets to better understand their sizes and compositions.

NASA WISE Image: Helix Nebula

A dying star, called the Helix nebula, is shown surrounded by the tracks of asteroids in an image captured by NASA's Wide-field Infrared Survey Explorer (WISE). 

Image Credit: NASA/JPL-Caltech/UCLA

In an unexpected juxtaposition of cosmic objects that are actually quite far from each other, a newly released image from NASA's Wide-Field Infrared Survey Explorer (WISE) shows a dying star, called the Helix nebula, surrounded by the tracks of asteroids.

The nebula is far outside our solar system, while the asteroid tracks are inside our solar system.

The portrait, discovered by chance in a search for asteroids, comes at a time when the mission's team is celebrating its fourth launch anniversary -- and new lease on life.

In August, NASA decided to bring WISE out of hibernation to search for more asteroids. The mission was rechristened NEOWISE, formerly the name of the asteroid-hunting portion of WISE.

"I was recently looking for asteroids in images collected in 2010, and this picture jumped out at me," said Amy Mainzer, the NEOWISE principal investigator at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "I recognized the Helix nebula right away."

WISE launched into the morning skies above Vandenberg Air Force Base in central California on Dec. 14, 2009.

By early 2011, it had finished scanning the entire sky twice in infrared light, snapping pictures of nearly one billion objects, including remote galaxies, stars and asteroids.

Upon completing its main goals, WISE was put to sleep. Now, engineers are bringing the spacecraft out of slumber, as it cools back down to the chilly temperatures required for infrared observations.

The spacecraft no longer has onboard coolant, but two of its infrared channels still work and can be used for asteroid hunting.

"WISE is the spacecraft that keeps on giving," said Ned Wright of UCLA, the principal investigator of WISE before it transitioned into NEOWISE.

In the Helix nebula image, infrared wavelengths of light have been assigned different colors, with longer wavelengths being red, and shorter, blue.

The bluish-green and red materials are expelled remnants of what was once a star similar to our sun. As the star aged, it puffed up and its outer layers sloughed off.

The burnt-out core of the star, called a white dwarf, is heating the expelled material, inducing it to glow with infrared light.

Over time, the brilliant object, known as a planetary nebula, will fade away, leaving just the white dwarf.

NASA WISE: Massive black hole duo

Two black holes are entwined in a gravitational tango in this artist's conception. 

Supermassive black holes at the hearts of galaxies are thought to form through the merging of smaller, yet still massive black holes, such as the ones depicted here. 

NASA's Wide-field Infrared Survey Explorer (WISE), helped lead astronomers to what appears to be a new example of a dancing black hole duo. 

Called WISE J233237.05-505643.5, the suspected black hole merger is located about 3.8 billion light-years from Earth, much farther than other black hole binary candidates of a similar nature. 

Credit: NASA

Astronomers have spotted what appear to be two supermassive black holes at the heart of a remote galaxy, circling each other like dance partners.

The incredibly rare sighting was made with the help of NASA's Wide-field Infrared Survey Explorer (WISE).

Follow-up observations with the Australian Telescope Compact Array near Narrabri, Australia, and the Gemini South telescope in Chile, revealed unusual features in the galaxy, including a lumpy jet thought to be the result of one black hole causing the jet of the other to sway.

"We think the jet of one black hole is being wiggled by the other, like a dance with ribbons," said Chao-Wei Tsai of NASA's Jet Propulsion Laboratory, Pasadena, Calif., who is lead author of a paper on the findings appearing in the Dec. 10 issue of Astrophysical Journal.

"If so, it is likely the two black holes are fairly close and gravitationally entwined."

The findings could teach astronomers more about how supermassive black holes grow by merging with each other.

The WISE satellite scanned the entire sky twice in infrared wavelengths before being put into hibernation in 2011. NASA recently gave the spacecraft a second lease on life, waking it up to search for asteroids, in a project called NEOWISE.

The new study took advantage of previously released all-sky WISE data. Astronomers sifted through images of millions of actively feeding supermassive black holes spread throughout our sky before an oddball, also known as WISE J233237.05-505643.5, jumped out.

"At first we thought this galaxy's unusual properties seen by WISE might mean it was forming new stars at a furious rate," said Peter Eisenhardt, WISE project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and a co-author of the study.

"But on closer inspection, it looks more like the death spiral of merging giant black holes."

Almost every large galaxy is thought to harbor a supermassive black hole filled with the equivalent in mass of up to billions of suns.

How did the black holes grow so large? One way is by swallowing ambient materials. Another way is through galactic cannibalism.

When galaxies collide, their massive black holes sink to the center of the new structure, becoming locked in a gravitational tango. Eventually, they merge into one even-more-massive black hole.

More information: Preprint paper: arxiv.org/abs/1310.2257

NASA WISE reveals the Milky Way's ancient brown dwarf population

A brown dwarf from the thick-disk or halo is shown. 

Although astronomers observe these objects as they pass near to the solar system, they spend much of their time away from the busiest part of the Galaxy, and the Milky Way's disk can be seen in the background. 

Credit: John Pinfield

A team of astronomers led by Dr David Pinfield at the University of Hertfordshire have discovered two of the oldest brown dwarfs in the Galaxy.

These ancient objects are moving at speeds of 100-200 kilometres per second, much faster than normal stars and other brown dwarfs and are thought to have formed when the Galaxy was very young, more than 10 billion years ago.

Intriguingly the scientists believe they could be part of a vast and previously unseen population of objects. The researchers publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

Brown dwarfs are star-like objects but are much less massive (with less than 7% of the Sun's mass), and do not generate internal heat through nuclear fusion like stars.

Because of this brown dwarfs simply cool and fade with time and very old brown dwarfs become very cool indeed - the new discoveries have temperatures of 250-600 degrees Celsius, much cooler than stars (in comparison the Sun has a surface temperature of 5600 degrees Celsius).

Pinfield's team identified the new objects in the survey made by the Wide-field Infrared Survey Explorer (WISE), a NASA observatory that scanned the mid-infrared sky from orbit in 2010 and 2011.

The object names are WISE 0013+0634 and WISE 0833+0052, and they lie in the Pisces and Hydra constellations respectively.

Additional measurements confirming the nature of the objects came from large ground-based telescopes (Magellan, Gemini, VISTA and UKIRT).

The infrared sky is full of faint red sources, including reddened stars, faint background galaxies (large distances from our own Milky Way) and nebulous gas and dust.

Identifying cool brown dwarfs in amongst this messy mixture is akin to finding needles in a haystack. But Pinfield's team developed a new method that takes advantage of the way in which WISE scans the sky multiple times.

This allowed them to identify cool brown dwarfs that were fainter than other searches had revealed.

The team of scientists then studied the infrared light emitted from these objects, which are unusual compared to typical slower moving brown dwarfs.

The spectral signatures of their light reflects their ancient atmospheres, which are almost entirely made up of hydrogen rather than having the more abundant heavier elements seen in younger stars.

Pinfield comments on their venerable ages and high speeds, "Unlike in other walks of life, the Galaxy's oldest members move much faster than its younger population".

More information: "A deep WISE search for very late type objects and the discovery of two halo/thick-disk T dwarfs: WISE 0013+0634 and WISE 0833+0052", D. J. Pinfield et al, Monthly Notices of the Royal Astronomical Society, in press. A pre-publication version of the paper is available on arXiv: arxiv.org/abs/1308.0495

NASA WISE: Retired Satellite Telescope to be Re-activated

NASA is considering re-activating a mothballed space telescope to help find asteroids that could be on a collision course with Earth, according to a senior U.S. space agency official.

Launched in December 2009, the Wide-field Infrared Survey Explorer (WISE), telescope spent about a year taking pictures for an all-sky map.

With its infrared detectors, WISE was able to peer through thick layers of dust and see even relatively dim objects such as cool brown dwarf stars in great detail.

NASA then put WISE to work on another mission looking for asteroids and comets in the solar system. Of particular interest were objects in orbits that pass relatively close to Earth.

WISE found about 150 near-Earth asteroids, including 20 that were potentially hazardous, before funding for the project ran out. The telescope was put into hibernation in February 2011.

Lindley Johnson

NASA is now reviewing options for enhancing its asteroid-hunting efforts including bringing WISE out of hibernation, Lindley Johnson, who oversees the agency's Near-Earth Objects observations program, said this week.

This follows February's explosion of a small asteroid in the skies above Russia and the near-Earth passage of a larger one the same day.

More than 1,500 people were hurt by flying glass and debris after that small asteroid exploded above Chelyabinsk, Russia.

The larger asteroid then zipped past Earth closer than the networks of communication satellites that ring the planet.

Together, those events served as a celestial alarm clock, prompting congressional hearings and fresh calls for NASA and other agencies to step up asteroid detection initiatives.

NASA says it already has found about 95 percent of the asteroids that are .62 miles or larger in diameter.

"If an object of that size were to impact the Earth, it would have global consequences," Lindley said during a NASA advisory committee meeting in Washington.

"One as much as 100 meters (328 feet) in size would have regional effects and could cause a great many casualties."

The Obama administration has requested funding from Congress to double NASA's $20 million Near-Earth Objects detection programs for the 2014 fiscal year beginning October 1.

Costs for WISE's potential re-activation and operation were not released, but Johnson said it may be possible within the program's current $20 million annual budget and would easily fit within the proposed $40 million spending plan.

NASA's human exploration program also has been developing an initiative to send a robotic spacecraft to a small nearby asteroid and redirect it into a high orbit around the moon, officials said.

Astronauts would then visit the asteroid as part of an initial foray to send humans beyond the International Space Station, which flies about 250 miles above Earth.

Another $85 million in Obama's $17.7 billion 2014 spending plan for NASA would start technology developments and planning for the robotic portion of the asteroid encounter.

NASA is about halfway through a 15-year effort to find 90 percent of all near-Earth objects that are as small as about 459 feet in diameter.

Scientists say one of the quickest ways to speed up the effort is to re-activate WISE. "We think it can be operated for three years and get much more data," Johnson said.

Time is of the essence as WISE is expected to slip from its optimal viewing orbit around Earth by early 2017.

NASA's WISE discover rare galaxy furiously burning fuel for stars

The tiny red spot in this image is one of the most efficient star-making galaxies ever observed, converting gas into stars at the maximum possible rate. 

The galaxy is shown here in an image from NASA's Wide-field Infrared Survey Explorer (WISE), which first spotted the rare galaxy in infrared light. 

Credit: NASA/JPL-Caltech/STScI/IRAM

Astronomers have found a galaxy turning gas into stars with almost 100 percent efficiency, a rare phase of galaxy evolution that is the most extreme yet observed.

The findings come from the IRAM Plateau de Bure interferometer in the French Alps, NASA's Wide-field Infrared Survey Explorer and NASA's Hubble Space Telescope.

Jim Geach

"Galaxies burn gas like a car engine burns fuel. Most galaxies have fairly inefficient engines, meaning they form stars from their stellar fuel tanks far below the maximum theoretical rate," said Jim Geach of McGill University, lead author of a new study appearing in the Astrophysical Journal Letters.

"This galaxy is like a highly tuned sports car, converting gas to stars at the most efficient rate thought to be possible," he said.

The galaxy, called SDSSJ1506+54, jumped out at the researchers when they looked at it using data from WISE's all-sky infrared survey. Infrared light is pouring out of the galaxy, equivalent to more than a thousand billion times the energy of our sun.

Ned Wright

"Because WISE scanned the entire sky, it detected rare galaxies like this one that stand out from the rest," said Ned Wright of UCLA, the WISE principal investigator.

Hubble's visible-light observations revealed that the galaxy is extremely compact, with most of its light emanating from a region just a few hundred light-years across.

"This galaxy is forming stars at a rate hundreds of times faster than our Milky Way galaxy, but the sharp vision of Hubble revealed that the majority of the galaxy's starlight is being emitted by a region just a few percent of the diameter of the Milky Way. This is star formation at its most extreme," said Geach.

The team then used the IRAM Plateau de Bure Interferometer to measure the amount of gas in the galaxy. The ground-based telescope detected millimeter-wave light coming from carbon monoxide, an indicator of the presence of hydrogen gas, which is fuel for stars.

Combining the rate of star formation derived with WISE, and the gas mass measured by IRAM, the scientists get a measure of the star formation efficiency.

The results reveal that the star-forming efficiency of the galaxy is close to the theoretical maximum, called the Eddington limit. In regions of galaxies where new stars are forming, parts of gas clouds are collapsing due to gravity. When the gas is dense enough to squeeze atoms together and ignite nuclear fusion, a star is born.

At the same time, winds and radiation from stars that have just formed can prevent the formation of new stars by exerting pressure on the surrounding gas, curtailing the collapse.

The Eddington limit is the point at which the force of gravity pulling gas together is balanced by the outward pressure from the stars. Above the Eddington limit, the gas clouds would be blown apart, halting star formation.

NASA GALEX, Spitzer, WISE Image: Helix Nebula - Unraveling

A dying star is throwing a cosmic tantrum in this combined image from NASA's Spitzer Space Telescope and the Galaxy Evolution Explorer (GALEX), which NASA has lent to the California Institute of Technology in Pasadena.

In death, the star's dusty outer layers are unraveling into space, glowing from the intense ultraviolet radiation being pumped out by the hot stellar core.

This object, called the Helix nebula, lies 650 light-years away, in the constellation of Aquarius.

Also known by the catalog number NGC 7293, it is a typical example of a class of objects called planetary nebulae.

Discovered in the 18th century, these cosmic works of art were erroneously named for their resemblance to gas-giant planets.

Planetary nebulae are actually the remains of stars that once looked a lot like our sun.

These stars spend most of their lives turning hydrogen into helium in massive runaway nuclear fusion reactions in their cores.

In fact, this process of fusion provides all the light and heat that we get from our sun. Our sun will blossom into a planetary nebula when it dies in about five billion years.

When the hydrogen fuel for the fusion reaction runs out, the star turns to helium for a fuel source, burning it into an even heavier mix of carbon, nitrogen and oxygen.

Eventually, the helium will also be exhausted, and the star dies, puffing off its outer gaseous layers and leaving behind the tiny, hot, dense core, called a white dwarf.

The white dwarf is about the size of Earth, but has a mass very close to that of the original star; in fact, a teaspoon of a white dwarf would weigh as much as a few elephants!

The glow from planetary nebulae is particularly intriguing as it appears surprisingly similar across a broad swath of the spectrum, from ultraviolet to infrared.

The Helix remains recognizable at any of these wavelengths, but the combination shown here highlights some subtle differences.

The intense ultraviolet radiation from the white dwarf heats up the expelled layers of gas, which shine brightly in the infrared.

GALEX has picked out the ultraviolet light pouring out of this system, shown throughout the nebula in blue, while Spitzer has snagged the detailed infrared signature of the dust and gas in yellow

A portion of the extended field beyond the nebula, which was not observed by Spitzer, is from NASA's all-sky Wide-field Infrared Survey Explorer (WISE). The white dwarf star itself is a tiny white pinprick right at the center of the nebula.

The brighter purple circle in the very center is the combined ultraviolet and infrared glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved).

This dust was most likely kicked up by comets that survived the death of their star.

Before the star died, its comets, and possibly planets, would have orbited the star in an orderly fashion.

When the star ran out of hydrogen to burn, and blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, kicking up an ongoing cosmic dust storm.

Any inner planets in the system would have burned up or been swallowed as their dying star expanded.

Infrared data from Spitzer for the central nebula is rendered in green (wavelengths of 3.6 to 4.5 microns) and red (8 to 24 microns), with WISE data covering the outer areas in green (3.4 to 4.5 microns) and red (12 to 22 microns). Ultraviolet data from GALEX appears as blue (0.15 to 2.3 microns).

Image Credit: NASA/JPL-Caltech

NASA WISE Image: The Flame Nebula

The Flame Nebula sits on the eastern hip of Orion the Hunter, a constellation most easily visible in the northern hemisphere during winter evenings.

This view of the nebula was taken by WISE, NASA's Wide-field Infrared Survey Explorer.

This image shows a vast cloud of gas and dust where new stars are being born.

Three familiar nebulae are visible in the central region: the Flame Nebula, the Horsehead Nebula and NGC 2023.

The Flame Nebula is the brightest and largest in the image. It is lit by a star inside it that is 20 times the mass of the sun and would be as bright to our eyes as the other stars in Orion's belt if it weren't for all the surrounding dust, which makes it appear 4 billion times dimmer than it actually is.

Images from NASA's Wide-field Infrared Survey Explorer (WISE) reveal an old star in the throes of a fiery outburst, spraying the cosmos with dust.

The findings offer a rare, real-time look at the process by which stars like our sun seed the universe with building blocks for other stars, planets and even life.

 The star, catalogued as WISE J180956.27-330500.2, was discovered in images taken during the WISE survey in 2010, the most detailed infrared survey to date of the entire celestial sky.

It stood out from other objects because it glowed brightly with infrared light. When compared to images taken more than 20 years ago, astronomers found the star was 100 times brighter.

"We were not searching specifically for this phenomenon, but because WISE scanned the whole sky, we can find such unique objects," said Poshak Gandhi of the Japan Aerospace Exploration Agency (JAXA), lead author of a new paper to be published in the Astrophysical Journal Letters.

Results indicate the star recently exploded with copious amounts of fresh dust, equivalent in mass to our planet Earth. The star is heating the dust and causing it to glow with infrared light.

"Observing this period of explosive change while it is actually ongoing is very rare," said co-author Issei Yamamura of JAXA.

"These dust eruptions probably occur only once every 10,000 years in the lives of old stars, and they are thought to last less than a few hundred years each time. It's the blink of an eye in cosmological terms."

The aging star is in the "red giant" phase of its life. Our own sun will expand into a red giant in about 5 billion years.

When a star begins to run out of fuel, it cools and expands. As the star puffs up, it sheds layers of gas that cool and congeal into tiny dust particles.

This is one of the main ways dust is recycled in our universe, making its way from older stars to newborn solar systems.

The other way, in which the heaviest of elements are made, is through the deathly explosions, or supernovae, of the most massive stars.

"It's an intriguing glimpse into the cosmic recycling program," said Bill Danchi, WISE program scientist at NASA Headquarters in Washington. "Evolved stars, which this one appears to be, contribute about 50 percent of the particles that make up humans."

NASA Wise Image: The latest infra-red map of the Universe

The map of the whole sky was compiled by NASA's infrared space telescope, WISE, and is made up of 560 million stars, galaxies and other objects.

The Milky Way's disk and central bulge are traced out in blue, representing infrared light with a wavelength of 3.4 micrometres, which mainly comes from stars.

The bluish blobs to the bottom right are our two largest satellite galaxies, the Large and Small Magellanic clouds, more than 150,000 light years away. Andromeda forms a small blue streak to the lower left, and the image is dotted with more distant galaxies.

Longer-wavelength radiation, coloured green and red, comes from dust clouds. Just above the galactic disk near the centre of the image is the Rho Ophiuchi cloud complex, only 130 light years away, where new stars are forming.

Among the discoveries made by WISE are many near-Earth asteroids, as well as a new class of super-cool stars called Y-dwarfs.

NASA WISE Image: Cosmic clouds bubbling with new star birth

A new, large mosaic from NASA's Wide-Field Infrared Survey Explorer (WISE) showcases a vast stretch of cosmic clouds bubbling with new star birth.

The region - a 1,000-square-degree chunk of our Milky Way galaxy - is home to numerous star-forming clouds, where massive stars have blown out bubbles in the gas and dust.

"Massive stars sweep up and destroy their natal clouds, but they continuously spark new stars to form along the way," said WISE Mission Scientist Dave Leisawitz of NASA Goddard Space Flight Center, Greenbelt, Md. Leisawitz is co-author of a new paper reporting the results in the Astrophysical Journal.

"Occasionally a new, massive star forms, perpetuating the sequence of events and giving rise to the dazzling fireworks display seen in this WISE mosaic."

The WISE space telescope mapped the entire sky two times in infrared light, completing its survey in February of 2011. Astronomers studying how stars form took advantage of WISE's all-encompassing view by studying several star-forming clouds, or nebulae, including 10 pictured in this new view.

The observations provide new evidence for a process called triggered star formation, in which the winds and sizzling radiation from massive stars compress gas and dust, inducing a second generation of stars. The same winds and radiation carve out the cavities, or bubbles, seen throughout the image.

Finding evidence for triggered star formation has proved more difficult than some might think. Astronomers are not able to watch the stars grow and evolve like biologists watching zebras in the wild.

Instead, they piece together a history of star formation by looking at distinct stages in the process. It's the equivalent of observing only baby, middle-aged and elderly zebras with crude indicators of their ages. WISE is helping to fill in these gaps by providing more and more "specimens" for study.

"Each region we looked at gave us a single snapshot of star formation in progress," said Xavier Koenig, lead author of the new study at Goddard, who presented the results in Austin, Texas, at the 219th meeting of the American Astronomical Society. "But when we look at a whole collection of regions, we can piece together the chain of events."

After looking at several of the star-forming nebulae, Koenig and his colleagues noticed a pattern in the spatial arrangement of newborn stars. Some were found lining the blown-out cavities, a phenomenon that had been seen before, but other new stars were seen sprinkled throughout the cavity interiors.

The results suggest that stars are born in a successive fashion, one after the other, starting from a core cluster of massive stars and moving steadily outward. This lends support to the triggered star formation theory, and offers new clues about the physics of the process.

The astronomers also found evidence that the bubbles seen in the star-forming clouds can spawn new bubbles. In this scenario, a massive star blasts away surrounding material, eventually triggering the birth of another star massive enough to carve out its own bubble. A few examples of what may be first- and second-generation bubbles can be seen in the new WISE image.

"I can almost hear the stars pop and crackle," said Leisawitz.