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.

Fermi finds a mysterious 'transformer' pulsar

These artist's renderings show one model of pulsar J1023 before (top) and after (bottom) its radio beacon (green) vanished. 

Normally, the pulsar's wind staves off the companion's gas stream. 

When the stream surges, an accretion disk forms and gamma-ray particle jets (magenta) obscure the radio beam. 

Credit: NASA's Goddard Space Flight Center

In late June 2013, an exceptional binary containing a rapidly spinning neutron star underwent a dramatic change in behavior never before observed.

The pulsar's radio beacon vanished, while at the same time the system brightened fivefold in gamma rays, the most powerful form of light, according to measurements by NASA's Fermi Gamma-ray Space Telescope.

"It's almost as if someone flipped a switch, morphing the system from a lower-energy state to a higher-energy one," said Benjamin Stappers, an astrophysicist at the University of Manchester, England, who led an international effort to understand this striking transformation.

"The change appears to reflect an erratic interaction between the pulsar and its companion, one that allows us an opportunity to explore a rare transitional phase in the life of this binary."

A binary consists of two stars orbiting around their common center of mass. This system, known as AY Sextantis, is located about 4,400 light-years away in the constellation Sextans.

It pairs a 1.7-millisecond pulsar named PSR J1023+0038 (J1023) with a star containing about one-fifth the mass of the sun.

The stars complete an orbit in only 4.8 hours, which places them so close together that the pulsar will gradually evaporate its companion.

When a massive star collapses and explodes as a supernova, its crushed core may survive as a compact remnant called a neutron star or pulsar, an object squeezing more mass than the sun's into a sphere no larger than Washington, D.C.

Young isolated neutron stars rotate tens of times each second and generate beams of radio, visible light, X-rays and gamma rays that astronomers observe as pulses whenever the beams sweep past Earth.

Pulsars also generate powerful outflows, or "winds," of high-energy particles moving near the speed of light.

The power for all this comes from the pulsar's rapidly spinning magnetic field, and over time, as the pulsars wind down, these emissions fade.

More than 30 years ago, astronomers discovered another type of pulsar revolving in 10 milliseconds or less, reaching rotational speeds up to 43,000 rpm.

While young pulsars usually appear in isolation, more than half of millisecond pulsars occur in binary systems, which suggested an explanation for their rapid spin.

"Astronomers have long suspected millisecond pulsars were spun up through the transfer and accumulation of matter from their companion stars, so we often refer to them as recycled pulsars," explained Anne Archibald, a postdoctoral researcher at the Netherlands Institute for Radio Astronomy (ASTRON) in Dwingeloo who discovered J1023 in 2007.


Zoom into an artist's concept of AY Sextantis, a binary star system whose pulsar switched from radio emissions to high-energy gamma rays in 2013. 

This transition likely means the pulsar's spin-up process is nearing its end. 

Credit: NASA FERMI

During the initial mass-transfer stage, the system would qualify as a low-mass X-ray binary, with a slower-spinning neutron star emitting X-ray pulses as hot gas raced toward its surface.

A billion years later, when the flow of matter comes to a halt, the system would be classified as a spun-up millisecond pulsar with radio emissions powered by a rapidly rotating magnetic field.

To better understand J1023's spin and orbital evolution, the system was regularly monitored in radio using the Lovell Telescope in the United Kingdom and the Westerbork Synthesis Radio Telescope in the Netherlands.

These observations revealed that the pulsar's radio signal had turned off and prompted the search for an associated change in its gamma-ray properties.

A few months before this, astronomers found a much more distant system that flipped between radio and X-ray states in a matter of weeks.

Located in M28, a globular star cluster about 19,000 light-years away, a pulsar known as PSR J1824-2452I underwent an X-ray outburst in March and April 2013. As the X-ray emission dimmed in early May, the pulsar's radio beam emerged.

While J1023 reached much higher energies and is considerably closer, both binaries are otherwise quite similar. What's happening, astronomers say, are the last sputtering throes of the spin-up process for these pulsars.

In J1023, the stars are close enough that a stream of gas flows from the sun-like star toward the pulsar. The pulsar's rapid rotation and intense magnetic field are responsible for both the radio beam and its powerful pulsar wind.

When the radio beam is detectable, the pulsar wind holds back the companion's gas stream, preventing it from approaching too closely but now and then the stream surges, pushing its way closer to the pulsar and establishing an accretion disk.

Gas in the disk becomes compressed and heated, reaching temperatures hot enough to emit X-rays. Next, material along the inner edge of the disk quickly loses orbital energy and descends toward the pulsar.

When it falls to an altitude of about 50 miles (80 km), processes involved in creating the radio beam are either shut down or, more likely, obscured.

The inner edge of the disk probably fluctuates considerably at this altitude. Some of it may become accelerated outward at nearly the speed of light, forming dual particle jets firing in opposite directions, a phenomenon more typically associated with accreting black holes.

Shock waves within and along the periphery of these jets are a likely source of the bright gamma-ray emission detected by Fermi.

The findings were published in the July 20 edition of The Astrophysical Journal. The team reports that J1023 is the first example of a transient, compact, low-mass gamma-ray binary ever seen.

The researchers anticipate that the system will serve as a unique laboratory for understanding how millisecond pulsars form and for studying the details of how accretion takes place on neutron stars.

"So far, Fermi has increased the number of known gamma-ray pulsars by about 20 times and doubled the number of millisecond pulsars within in our galaxy," said Julie McEnery, the project scientist for the mission at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"Fermi continues to be an amazing engine for pulsar discoveries."

More information: Paper: "A State Change In The Missing Link Binary Pulsar System PSR J1023+0038" iopscience.iop.org/0004-637X/790/1/39 - Paper: "A Radio Pulsar/X-ray Binary Link" arxiv.org/abs/0905.3397

Dark Energy Survey (DES): Five-year mission to map southern sky in detail

This image of the NGC 1398 galaxy was taken with the Dark Energy Camera (DECam). 

This galaxy lives in the Fornax cluster, roughly 65 million light years from Earth. 

It is 135,000 light years in diameter, just slightly larger than our own Milky Way galaxy, and contains more than a hundred million stars. 

Credit: Dark Energy Survey.

Tonight, as the sun sinks below the horizon, the world's most powerful digital camera will once again turn its gleaming eye skyward.

Tonight, and for hundreds of nights over the next five years, a team of physicists and astronomers from around the globe will use this remarkable machine to try to answer some of the most fundamental questions about our universe.

Dark Energy Survey - DECam: Fermilab  

On Aug. 31, the Dark Energy Survey (DES) officially began. Scientists on the survey team will systematically map one-eighth of the sky (5000 square degrees) in unprecedented detail.

The start of the survey is the culmination of 10 years of planning, building and testing by scientists from 25 institutions in six countries.

The survey's goal is to find out why the expansion of the universe is speeding up, instead of slowing down due to gravity, and to probe the mystery of dark energy, the force believed to be causing that acceleration.

James Siegrist

"The Dark Energy Survey will explore some of the most important questions about our existence," said James Siegrist, associate director for High Energy Physics at the U.S. Department of Energy's Office of Science.

"In five years' time, we will be far closer to the answers, and far richer in our knowledge of the universe."

"With the start of the survey, the work of more than 200 collaborators is coming to fruition," said DES Director Josh Frieman of the U.S. Department of Energy's Fermi National Accelerator Laboratory.

"It's an exciting time in cosmology, when we can use observations of the distant universe to tell us about the fundamental nature of matter, energy, space and time."

Composite Dark Energy Camera image of one of the sky regions that the collaboration will use to study supernovae, exploding stars that will help uncover the nature of dark energy. 

The outlines of each of the 62 Charged Coupled Devices can be seen. 

This picture spans 2 degrees across on the sky and contains 520 megapixels.

The survey will use four methods to probe dark energy:

• Counting galaxy clusters. While gravity pulls mass together to form galaxies, dark energy pulls it apart. The Dark Energy Camera will see light from 100,000 galaxy clusters billions of light-years away. Counting the number of galaxy clusters at different points in time sheds light on this cosmic competition between gravity and dark energy.
• Measuring supernovae. A supernova is a star that explodes and becomes as bright as an entire galaxy of billions of stars. By measuring how bright they appear on Earth, we can tell how far away they are. Scientists can use this information to determine how fast the universe has been expanding since the star's explosion. The survey will discover 4000 of these supernovae, which exploded billions of years ago in galaxies billions of light-years away. 
• Studying the bending of light. When light from distant galaxies encounters dark matter in space, it bends around the matter, causing those galaxies to appear distorted in telescope images. The survey will measure the shapes of 200 million galaxies, revealing the cosmic tug of war between gravity and dark energy in shaping the lumps of dark matter throughout space.
• Using sound waves to create a large-scale map of expansion over time. When the universe was less than 400,000 years old, the interplay between matter and light set off a series of sound waves traveling at nearly two-thirds the speed of light. Those waves left an imprint on how galaxies are distributed throughout the universe. The survey will measure the positions in space of 300 million galaxies to find this imprint and use it to infer the history of cosmic expansion.

NASA Fermi and Swift see 'shockingly bright' burst

The maps in this animation show how the sky looks at gamma-ray energies above 100 million electron volts with a view centered on the north galactic pole. 

The first frame shows the sky during a three-hour interval prior to GRB 130427A.

The second frame shows a three-hour interval starting 2.5 hours before the burst, and ending 30 minutes into the event. 

The Fermi team chose this interval to demonstrate how bright the burst was relative to the rest of the gamma-ray sky.

This burst was bright enough that Fermi autonomously left its normal surveying mode to give the LAT instrument a better view, so the three-hour exposure following the burst does not cover the whole sky in the usual way. 

Credit: NASA/DOE/Fermi LAT Collaboration

A record-setting blast of gamma rays from a dying star in a distant galaxy has wowed astronomers around the world.

The eruption, which is classified as a gamma-ray burst, or GRB, and designated GRB 130427A, produced the highest-energy light ever detected from such an event.

"We have waited a long time for a gamma-ray burst this shockingly, eye-wateringly bright," said Julie McEnery, project scientist for the Fermi Gamma-ray Space Telescope at NASA's Goddard Space Flight Center in Greenbelt, Md.

"The GRB lasted so long that a record number of telescopes on the ground were able to catch it while space-based observations were still ongoing."

Just after 3:47 a.m. EDT on Saturday, April 27, Fermi's Gamma-ray Burst Monitor (GBM) triggered on eruption of high-energy light in the constellation Leo.

The burst occurred as NASA's Swift satellite was slewing between targets, which delayed its Burst Alert Telescope's detection by a few seconds.

Fermi's Large Area Telescope (LAT) recorded one gamma ray with an energy of at least 94 billion electron volts (GeV), or some 35 billion times the energy of visible light, and about three times greater than the LAT's previous record.

The GeV emission from the burst lasted for hours, and it remained detectable by the LAT for the better part of a day, setting a new record for the longest gamma-ray emission from a GRB.

Swift's X-Ray Telescope took this 26.5-second exposure of GRB 130427A at 3:50 a.m. EDT on April 27, just moments after Swift and Fermi triggered on the outburst. The image is 6.5 arcminutes across. 

Credit: NASA /Swift /Stefan Immler

The burst subsequently was detected in optical, infrared and radio wavelengths by ground-based observatories, based on the rapid accurate position from Swift.

Astronomers quickly learned that the GRB was located about 3.6 billion light-years away, which for these events is relatively close.

Gamma-ray bursts are the universe's most luminous explosions. Astronomers think most occur when massive stars run out of nuclear fuel and collapse under their own weight. As the core collapses into a black hole, jets of material shoot outward at nearly the speed of light.

Stefan Immler

The jets bore all the way through the collapsing star and continue into space, where they interact with gas previously shed by the star and generate bright afterglows that fade with time.

If the GRB is near enough, astronomers usually discover a supernova at the site a week or so after the outburst.

This animation shows a more detailed Fermi LAT view of GRB 130427A. The sequence shows high-energy (100 Mev to 100 GeV) gamma rays from a 20-degree-wide region of the sky starting three minutes before the burst to 14 hours after.

Following an initial one-second spike, the LAT emission remained relatively quiet for the next 15 seconds while Fermi's GBM instrument showed bright, variable lower-energy emission. 

Then the burst re-brightened in the LAT over the next few minutes and remained bright for nearly half a day. 

Credit: NASA /DOE /Fermi LAT Collaboration

Neil Gehrels

"This GRB is in the closest 5 percent of bursts, so the big push now is to find an emerging supernova, which accompanies nearly all long GRBs at this distance," said Goddard's Neil Gehrels, principal investigator for Swift.

Ground-based observatories are monitoring the location of GRB 130427A and expect to find an underlying supernova by mid-month.

NASA Fermi Detects Super Solar Flare

NASA's Fermi Gamma-ray Space Telescope has witnessed the highest amount of energy ever emitted during a solar flare.

The solar flare occurred on 7 March, and was classified as X5.4, with x-class flares being the most powerful that erupt on the Sun.

The flare was the largest ever observed with the Large Area Telescope (LAT) aboard Fermi, briefly making the Sun the brightest object in the gamma-ray sky. Not only was the flare bright, it also lasted for around twenty hours, which surpasses previous events by at least twelve hours.

"For most of Fermi's four years in orbit, its LAT saw the Sun as a faint, steady gamma-ray source thanks to the impacts of high-speed particles called cosmic rays," said Nicola Omodei from Stanford University. "Now we're beginning to see what the Sun itself can do."

During the peak of the flare, the energy emitted from the Sun reached around four billion gigaelectron volts, which is 1,000 times greater than the Sun’s ordinary energy output.

Charged particles are accelerated during a solar flare, which collide with matter in the Sun’s photosphere to produce gamma rays. Fermi’s LAT performs a sweep of the sky every three hours, seeking out gamma rays that are between 20 megaelectron volts and 300 gigaelectron volts. Fermi also hosts the Gamma-ray Burst Monitor (GBM), which monitors lower energy events.

A less powerful solar flare was observed by both the LAT and GBM on 12 June 2010, which yielded some interesting results according to Michael Briggs at the University of Alabama. "Seeing the rise and fall of this brief flare in both instruments allowed us to determine that some of these particles were accelerated to two-thirds of the speed of light in as little as three seconds.”

"Merged with available theoretical models, Fermi observations will give us the ability to reconstruct the energies and types of particles that interact with the Sun during flares, an understanding that will open up whole new avenues in solar research," said Gerald Share from the University of Maryland.

Events such as this powerful solar flare will continue to become more common until the Sun reaches its peak in the current solar cycle in 2013.

NASA Fermi: Mysterious Objects at the Edge of the Electromagnetic Spectrum

From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or roughly half of the Milky Way's diameter, as shown in this illustration. 

Hints of the bubbles' edges were first observed in X-rays (blue) by ESA's ROSAT, a Germany-led mission operating in the 1990s. 

The gamma rays mapped by Fermi (magenta) extend much farther from the galaxy's plane. 

Credit: NASA's Goddard Space Flight Center.

The human eye is crucial to astronomy. Without the ability to see, the luminous universe of stars, planets and galaxies would be closed to us, unknown forever. Nevertheless, astronomers cannot shake their fascination with the invisible.

Outside the realm of human vision is an entire electromagnetic spectrum of wonders. Each type of light from radio waves to gamma-rays reveals something unique about the universe. Some wavelengths are best for studying black holes; others reveal newborn stars and planets; while others illuminate the earliest years of cosmic history.

NASA has many telescopes "working the wavelengths" up and down the electromagnetic spectrum. One of them, the Fermi Gamma-Ray Telescope orbiting Earth, has just crossed a new electromagnetic frontier.

"Fermi is picking up crazy-energetic photons," says Dave Thompson, an astrophysicist at NASA's Goddard Space Flight Center. "And it's detecting so many of them we've been able to produce the first all-sky map of the very high energy universe."

"This is what the sky looks like near the very edge of the electromagnetic spectrum, between 10 billion and 100 billion electron volts."

The light we see with human eyes consists of photons with energies in the range 2 to 3 electron volts. The gamma-rays Fermi detects are billions of times more energetic, from 20 million to more than 300 billion electron volts.

These gamma-ray photons are so energetic, they cannot be guided by the mirrors and lenses found in ordinary telescopes. Instead Fermi uses a sensor that is more like a Geiger counter than a telescope.

If we could wear Fermi's gamma ray "glasses," we'd witness powerful bullets of energy - individual gamma rays - from cosmic phenomena such as supermassive black holes and hypernova explosions. The sky would be a frenzy of activity.

Fermi telescope: Gamma-ray bursts' highest power side unveiled

Detectable for only a few seconds but possessing enormous energy, gamma-ray bursts are difficult to capture because their energy does not penetrate the Earth's atmosphere.

Now, thanks to an orbiting telescope, astrophysicists are filling in the unknowns surrounding these bursts and uncovering new questions.

The Fermi Gamma-Ray Space Telescope, formerly called the Gamma-Ray Large Area Space Telescope, launched on June 11, 2008. As part of its mission, the telescope records any gamma-ray bursts within its viewing area.

"Fermi is lucky to measure the highest energy portion of the gamma-ray burst emission, which last for hundreds to thousands of seconds -- maybe 20 minutes," said Péter Mészáros, Eberly Chair Professor of Astronomy and Astrophysics and Physics, Penn State.

Most gamma-ray bursts occur when stars that are more than 25 times larger than our sun come to the end of their lives. When the internal nuclear reaction in these stars ends, the star collapses in on itself and forms a black hole. The outer envelope of the star is ejected forming a supernova.

"The black hole is rotating rapidly and as it is swallowing the matter from the star, the rotation ejects a jet of material through the supernova envelope," said Mészáros.

This jet causes the gamma-ray burst, which briefly becomes the brightest thing in the sky. However, unlike supernovas that radiate in all directions, gamma-ray bursts radiate in a very narrow area, and Fermi sees only jets ejecting in its direction.

This, however, is the direction in which they send their highest energy photons. Any gamma-ray bursts on the other side of the black hole or even off at an angle are invisible to the telescope.

"We actually miss about 500 gamma-ray bursts for every one we detect," Mészáros told attendees today at the annual meeting of the American Association for the Advancement of Science in Vancouver, British Columbia.

The gamma-ray bursts that Fermi has seen have allowed astrophysicists to clarify previous theories about gamma-ray bursts.

"We have been able to rule out the simplest version of theories which combine quantum mechanics with gravity, although others remain to be tested," said Mészáros.

Mészáros notes that Fermi and other programs like the SWIFT telescope have shown that gamma-ray bursts last longer than we thought they did and that there are long and short gamma-ray bursts.

Read more about the SWIFT Telescope discovery here

ESA Planck and Fermi: Galactic Haze

This all-sky image shows the distribution of the Galactic Haze seen by ESA's Planck mission at microwave frequencies superimposed over the high-energy sky as seen by NASA's Fermi Gamma-ray Space Telescope.

The Planck data (shown here in red and yellow) correspond to the Haze emission at frequencies of 30 and 44 GHz, extending from and around the Galactic Centre.

The Fermi data (shown here in blue) correspond to observations performed at energies between 10 and 100 GeV and reveal two bubble-shaped, gamma-ray emitting structures extending from the Galactic Centre.

The two emission regions seen by Planck and Fermi at two opposite ends of the electromagnetic spectrum correlate spatially quite well and might indeed be a manifestation of the same population of electrons via different radiation processes.

Synchrotron emission associated with the Galactic Haze seen by Planck exhibits distinctly different characteristics from the synchrotron emission seen elsewhere in the Milky Way. Diffuse synchrotron emission in the Galaxy is interpreted as radiation from highly energetic electrons that have been accelerated in shocks created by supernova explosions.

Compared to this well-studied emission, the Galactic Haze has a 'harder' spectrum, meaning that its emission does not decline as rapidly with increasing frequency.

Several explanations have been proposed for this unusual behaviour, including enhanced supernova rates, galactic winds and even annihilation of dark-matter particles. Thus far, none of them have been confirmed and the issue remains open.

The Planck image includes the mask that has been used in the analysis of the data to exclude regions with strong foreground contamination due to the Galaxy's diffuse emission. The mask also includes strong point-like sources located over the whole sky.

Credits: ESA/Planck Collaboration (microwave); NASA/DOE/Fermi LAT/D. Finkbeiner et al. (gamma rays)

NASA Fermi Tycho Supernova: Cosmic Mystery

Gamma rays detected by NASA's Fermi space telescope show that the remnant of Tycho's supernova shines in the highest-energy form of light. 

This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data.

CREDIT: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS

A well-known exploded star that is pumping out powerful gamma rays may be the celestial smoking gun astronomers have in the search for the origins of some of the fastest-moving particles in the universe, a new study reports.

NASA's Fermi space telescope has detected gamma rays — the highest-energy form of light — emanating from the shattered husk of Tycho's supernova, a star that exploded in 1572.

The find could help astronomers pinpoint the origin of cosmic rays, super-speedy subatomic particles that crash constantly into Earth's atmosphere, researchers said.

Gamma-rays detected by Fermi's LAT show that the remnant of Tycho's supernova shines in the highest-energy form of light. 

This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data. (Credit: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS).

In early November 1572, observers on Earth witnessed the appearance of a "new star" in the constellation Cassiopeia, an event now recognised as the brightest naked-eye supernova in more than 400 years.

It's often called "Tycho's supernova" after the great Danish astronomer Tycho Brahe, who gained renown for his extensive study of the object.

Now, years of data collected by NASA's Fermi Gamma-Ray Space Telescope reveal that the shattered star's remains shine in high-energy gamma rays.

The detection gives astronomers another clue in understanding the origin of cosmic rays, subatomic particles - mainly protons - that move through space at nearly the speed of light.

Exactly where and how these particles attain such incredible energies has been a long-standing mystery because charged particles speeding through the galaxy are easily deflected by interstellar magnetic fields. This makes it impossible to track cosmic rays back to their sources.

"Fortunately, high-energy gamma rays are produced when cosmic rays strike interstellar gas and starlight. These gamma rays come to Fermi straight from their sources," said Francesco Giordano at the University of Bari and the National Institute of Nuclear Physics in Italy. He is the lead author of a paper describing the findings in the Dec. 7 edition of The Astrophysical Journal Letters.

Better understanding the origins of cosmic rays is one of Fermi's key goals. Its Large Area Telescope (LAT) scans the entire sky every three hours, gradually building up an ever-deeper view of the gamma-ray sky. Because gamma rays are the most energetic and penetrating form of light, they serve as signposts for the particle acceleration that gives rise to cosmic rays.

"This detection gives us another piece of evidence supporting the notion that supernova remnants can accelerate cosmic rays," said co-author Stefan Funk, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), jointly located at SLAC National Accelerator Laboratory and Stanford University, Calif.

In 1949, physicist Enrico Fermi - the satellite's namesake - suggested that the highest-energy cosmic rays were accelerated in the magnetic fields of interstellar gas clouds. In the decades that followed, astronomers showed that supernova remnants may be the galaxy's best candidate sites for this process.

NASA's Fermi Shows Highly Active Galaxies

Active galaxies called blazars make up the largest class of objects detected by Fermi's Large Area Telescope (LAT).

Massive black holes in the hearts of these galaxies fire particle jets in our direction.

Fermi team member Elizabeth Hays narrates this quick tour of blazars, which includes LAT movies showing how rapidly their emissions can change. 

Credit: NASA/Goddard Space Flight Center

Fermi's Latest Gamma-ray Census Highlights Cosmic Mysteries

Active galaxies called blazars constitute the single largest source class in the second Fermi LAT catalog, but nearly a third of the sources are unassociated with objects at any other wavelength. Their natures are unknown.

Credit: NASA's Goddard Space Flight Center.

Every three hours, NASA's Fermi Gamma-ray Space Telescope scans the entire sky and deepens its portrait of the high-energy universe. Every year, the satellite's scientists reanalyze all of the data it has collected, exploiting updated analysis methods to tease out new sources. These relatively steady sources are in addition to the numerous transient events Fermi detects, such as gamma-ray bursts in the distant universe and flares from the sun.

Earlier this year, the Fermi team released its second catalog of sources detected by the satellite's Large Area Telescope (LAT), producing an inventory of 1,873 objects shining with the highest-energy form of light.

"More than half of these sources are active galaxies, whose massive black holes are responsible for the gamma-ray emissions that the LAT detects," said Gino Tosti, an astrophysicist at the University of Perugia in Italy and currently a visiting scientist at SLAC National Accelerator Laboratory in Menlo Park, Calif.

One of the scientists who led the new compilation, Tosti presented a paper on the catalog at a meeting of the American Astronomical Society's High Energy Astrophysics Division in Newport, R.I.

"What is perhaps the most intriguing aspect of our new catalog is the large number of sources not associated with objects detected at any other wavelength," he noted.

Indeed, if the Fermi catalog were a recipe, the two major ingredients would be active galaxies and pure mystery. To them, add in a pinch of pulsars, a dollop of supernova remnants, and a dash of other celestial objects, such as globular star clusters and galaxies like our own Milky Way.

Astronomers delight in the possibility of finding new types of gamma-ray-emitting objects within the "unassociated sources" that constitute roughly a third of the catalog. But Fermi's LAT is revealing gamma-rays from an increasing - and sometimes, surprising - variety of astronomical objects. To highlight the range of LAT discoveries, the Fermi team created the following "top ten" list of five sources within the Milky Way and five beyond our galaxy.

NASA Fermi Telescope:

Click on the picture to play the video

WASHINGTON -- NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."

The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.

Finkbeiner and his team discovered the bubbles by processing publicly available data from Fermi's Large Area Telescope (LAT).

The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.

Other astronomers studying gamma rays hadn't detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way.

The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles.

Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges.


The structure's shape and emissions suggest it was formed as a result of a large and relatively rapid energy release - the source of which remains a mystery.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole.

While there is no evidence the Milky Way's black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's center several million years ago.

"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel, a scientist at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."

Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky Way. NASA's Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles.

The Fermi LAT team also revealed Tuesday the instrument's best picture of the gamma-ray sky, the result of two years of data collection.

"Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail," said Julie McEnery, Fermi project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

NASA's Fermi is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

"Since its launch in June 2008, Fermi repeatedly has proven itself to be a frontier facility, giving us new insights ranging from the nature of space-time to the first observations of a gamma-ray nova," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “These latest discoveries continue to demonstrate Fermi's outstanding performance.”

For more information about Fermi, visit: http://www.nasa.gov/fermi

NASA Fermi Space Telescope Points to our Earth

A NASA space telescope hunting for the most powerful explosions in the universe is turning its eye on Earth to hunt for tiny flashes of radiation to determine if they pose a potential hazard to passengers aboard high-flying airliners.

NASA’s Fermi Gamma-Ray Space Telescope has joined the search for mysterious gamma-ray flashes above thunderstorms, which are ultrabrief but could be a concern for air travelers, researchers said.

Just one millisecond blast of the so-called terrestrial gamma-ray flashes (TGFs) could expose passengers and crew aboard a nearby jetliner to the same level of radiation as 400 chest X-rays, according to a recent study.

Fermi, which NASA launched to seek out gamma-ray bursts — immensely powerful explosions in deep space, usually from a dying star — joined in the hunt several months ago to possibly uncover more about when and how TGFs occur around thunderstorms and lightning.

To do that, scientists are using one of the telescope’s monitoring sensors.

“Fermi-GBM [Gamma-Ray Burst Monitor] has the broadest energy coverage and highest sensitivity of any instruments that have observed, or will observe TGFs,” said Jerry Fishman, an astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, Ala.

Scientists first discovered the existence of TGFs by accident, when the Compton Gamma-Ray Observatory detected a flash in 1991. But they still do not know if it is lightning that triggers the phenomenon or whether TGFs provide the quick burst of electrons that may spark a lightning strike.

Research findings by Fishman and his team are expected to be published in the coming weeks by the American Geophysical Union.