Four Supernova Remnants: NASA’s Chandra X-ray Observatory Celebrates 15th Anniversary

Four Supernova Remnants

Credit: NASA/CXC/SAO

JPEG (308.7 kb) - Large JPEG (609.2 kb) - Tiff (45.6 MB)

More Images

**************** 
 
 A Tour of IGR J11014-6103

In commemoration of the 15th anniversary of NASA's Chandra X-ray Observatory, four newly processed images of supernova remnants dramatically illustrate Chandra's unique ability to explore high-energy processes in the cosmos (see the accompanying press release).

The images of the Tycho and G292.0+1.8 supernova remnants show how Chandra can trace the expanding debris of an exploded star and the associated shock waves that rumble through interstellar space at speeds of millions of miles per hour. The images of the Crab Nebula and 3C58 show how extremely dense, rapidly rotating neutron stars produced when a massive star explodes can create clouds of high-energy particles light years across that glow brightly in X-rays.

Tycho:

More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of the exploded star produced a shock wave moving outward into the surrounding interstellar gas, and another, reverse shock wave moving back into the expanding stellar debris. This Chandra image of Tycho reveals the dynamics of the explosion in exquisite detail. The outer shock has produced a rapidly moving shell of extremely high-energy electrons (blue), and the reverse shock has heated the expanding debris to millions of degrees (red and green). There is evidence from the Chandra data that these shock waves may be responsible for some of the cosmic rays - ultra-energetic particles - that pervade the Galaxy and constantly bombard the Earth.

G292.0+1.8:

At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. These oxygen-rich supernovas are of great interest to astronomers because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people. The X-ray image from Chandra shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen (yellow and orange), other elements such as magnesium (green) and silicon and sulfur (blue) that were forged in the star before it exploded.

The Crab Nebula:

In 1054 AD, Chinese astronomers and others around the world noticed a new bright object in the sky. This “new star” was, in fact, the supernova explosion that created what is now called the Crab Nebula. At the center of the Crab Nebula is an extremely dense, rapidly rotating neutron star left behind by the explosion. The neutron star, also known as a pulsar, is spewing out a blizzard of high-energy particles, producing the expanding X-ray nebula seen by Chandra. In this new image, lower-energy X-rays from Chandra are red, medium energy X-rays are green, and the highest-energy X-rays are blue.

3C58:

3C58 is the remnant of a supernova observed in the year 1181 AD by Chinese and Japanese astronomers. This new Chandra image shows the center of 3C58, which contains a rapidly spinning neutron star surrounded by a thick ring, or torus, of X-ray emission. The pulsar also has produced jets of X-rays blasting away from it to both the left and right, and extending trillions of miles. These jets are responsible for creating the elaborate web of loops and swirls revealed in the X-ray data. These features, similar to those found in the Crab, are evidence that 3C58 and others like it are capable of generating both swarms of high-energy particles and powerful magnetic fields. In this image, low, medium, and high-energy X-rays detected by Chandra are red, green, and blue respectively.

****************

Fast Facts for 3C58:

Scale: Image is 12 arcmin across (35 light years) across.

Category: Neutron Stars/X-ray Binaries, Supernovas & Supernova Remnants

Coordinates (J2000): RA 02h 05m 37.00s | Dec +64 49 48.00

Constellation: Cassiopeia

Observation Dates: 4 pointings between Sep 2000 and Apr 2003

Observation Time: 108 hours 52 min (4 days 12 hours 52 min

Obs. IDs: 728, 3832, 4382, 4383

Instrument: ACIS

Color Code: X-ray (Red, Green, Blue)

Distance Estimate: About 10,000 light years

****************
   

Fast Facts for Crab Nebula:

Scale: Image is 4.6 arcmin across (8.7 light years) across.

Category: Neutron Stars/X-ray Binaries, Supernovas & Supernova Remnants

Coordinates (J2000): RA 05h 34m 32s | Dec +22 0.0 52.00

Constellation: Taurus

Observation Dates: 48 pointings between March 2000 and Nov 2013

Observation Time: 25 hours 28 min (1 day 1 hour 28 min)

Obs. IDs: 769-773,1994-2001,4607,13139,13146,13147,13150-13154,13204-132

Instrument: ACIS

Color Code: X-ray (Red, Green, Blue)

Distance Estimate: About 6,500 light years light years

**************** 

Fast Facts for Tycho's Supernova Remnant:

Scale: Image is 9.5 arcmin across (36 light years) across.

Category: Neutron Stars/X-ray Binaries, Supernovas & Supernova Remnants

Coordinates (J2000): RA 00h 25m 17s | Dec +64 08 37

Constellation: Cassiopeia

Observation Dates: 13 pointings between Sep 2000 and May 2009

Observation Time: 297 hours 26 min (12 days 9 hours 26 min)

Obs. IDs: 115, 3837, 7639, 8551, 10093-10097, 10902-10906

Instrument: ACIS

Also Knows As: G120.1+01.4, SN 1572

Color Code: X-ray (Red, Green, Blue)

Distance Estimate: About 6,500 light years light years

**************** 

Fast Facts for G292.0+1.8:

Scale: Image is 11.4 arcmin across (about 66 light years) across.

Category: Neutron Stars/X-ray Binaries, Supernovas & Supernova Remnants

Coordinates (J2000): RA 11h 24m 36.00s | Dec -59 16 00.00

Constellation: Centaurus

Observation Dates: 6 pointings between 13 Sep and 16 Oct 2006

Observation Time: 141 hours 30 min (5 days 21 hours 30 min)

Obs. IDs: 6677-6680, 8221, 8447

Instrument: ACIS

Color Code: X-ray X-ray (Red, Orange, Green, Blue)

Distance Estimate: About 20,000 light years light years

Source: NASA’s Chandra X-ray Observatory

An Image Gallery Gift from NASA's Swift

Of the three telescopes carried by NASA's Swift satellite, only one captures cosmic light at energies similar to those seen by the human eye. Although small by the standards of ground-based observatories, Swift's Ultraviolet/Optical Telescope (UVOT) plays a critical role in rapidly pinpointing the locations of gamma-ray bursts (GRBs), the brightest explosions in the cosmos.

 But as the proxy to the human eye aboard Swift, the UVOT takes some amazing pictures. The Swift team is celebrating eight years of UVOT operations by collecting more than 100 of the instrument's best snapshots in a web-based photo gallery. The images also can be viewed with the free Swift Explorer Mission iPhone app developed by the Swift Mission Operations Center (MOC), which is located in State College, Pa., and operated by Penn State.

The Crab Nebula is the wreckage of an exploded star, or supernova, observed in the year 1054. The expanding cloud of gas is located 6,500 light-years away in the constellation Taurus. This composite of three Swift UVOT ultraviolet images highlights the luminous hot gas in the supernova remnant. The image is constructed from exposures using these filters: uvw1, centered at 2,600 angstroms (shown as red); uvm2, centered at 2,246 angstroms (green); and uvw2, centered at 1,928 angstroms (blue). Credit: NASA/Swift/E. Hoversten, PSU

› Larger image (labeled) - › Larger image (unlabeled)

 Swift has detected an average of about 90 GRBs a year since its launch in 2004. "When we aren't studying GRBs, we use the satellite's unique capabilities to engage in other scientific investigations, some of which produce beautiful images from the UVOT that we're delighted to be able to share with the public," said Michael Siegel, the lead scientist on the UVOT and a research associate in astronomy and astrophysics at the MOC.

 The targets range from comets and star clusters to supernova remnants, nearby galaxies and active galaxies powered by supermassive black holes.

 "One of our more challenging projects in the past was completing an ultraviolet mosaic of M31, the famous Andromeda galaxy," said Stefan Immler, a member of the Swift team at NASA's Goddard Space Flight Center in Greenbelt, Md. "Because the galaxy is so much larger than the UVOT field of view, we had to take dozens of pictures and blend them together to show the whole object."

 An ongoing mosaic project targets the Large and Small Magellanic Clouds, two small satellite galaxies orbiting our own, and makes the Andromeda effort look like child's play. Although the galaxies are much smaller than M31, they are both much closer to us and extend over much larger areas of the sky. The task involves acquiring and aligning hundreds of images and is far from complete.

 With the UVOT's wavelength range of 1,700 to 6,000 angstroms, Swift remains one of few missions that study ultraviolet light, much of which is blocked by Earth's atmosphere.

Omega Centauri (also known as NGC 5139) is the largest, brightest and most massive of our galaxy's retinue of 150 or so globular star clusters. Packing some 10 million stars into a region just 150 light-years across, Omega Centauri is easily visible to the unaided eye despite lying nearly 16,000 light-years away. Unlike other star clusters, whose members all have similar age and chemical makeup, Omega Centauri displays a wide range of age and chemistry, from the ancient (12 billion years) to the relatively recent. The presence of different stellar populations suggests that Omega Centauri is not, in fact, a globular cluster, but the remnant core of a dwarf galaxy torn to shreds by the Milky Way’s gravity. The false-color ultraviolet composite from Swift UVOT's uvw1, uvm2 and uvw2 filters reveals a treasure trove of rare stars in various stages of demise. Credit: NASA/Swift/S. Holland (Goddard), M. Siegel and E. Fonseca (PSU)

› Larger image (labeled) - › Larger image (unlabeled)

 The 6.5-foot-long (2 meter) UVOT is centered on an 11.8-inch (30 cm) primary mirror. Designed and built by the Mullard Space Science Laboratory in Surrey, England, the telescope module includes the primary and secondary mirrors, an external baffle to reduce scattered light, two redundant detectors -- only one has been used to date -- and a power supply.

 Each detector lies behind an identical filter wheel. The wheel holds color filters that transmit a broad range of wavelengths as well as devices called grisms, which spread out incoming light in much the same way as a prism spreads sunlight into a rainbow of component colors. The detectors retain information on the position and arrival time of each photon of light, an operating mode similar to typical X-ray telescopes.

 Because most ultraviolet light never reaches the ground, Swift's UVOT provides a unique perspective on the cosmos. For example, it can measure the amount of water produced in passing comets by detecting the ultraviolet emission of hydroxyl (OH), one of the molecular fragments created when ultraviolet sunlight breaks up water molecules. Other types of UVOT science include exploring emissions from the centers of active galaxies, studying regions undergoing star formation, and identifying some of the rarest and most exotic stars known.

Technicians prepare Swift's UVOT for vibration testing on Aug. 1, 2002, more than two years before launch, in the High Bay Clean Room at NASA's Goddard Space Flight Center in Greenbelt, Md. Credit: NASA's Goddard Space Flight Center. › Larger image

Toward the end of its energy-producing life, a star like the sun will blow away its outer layers as its core transforms into a compact, Earth-sized remnant known as a white dwarf. This chapter of stellar evolution, known to astronomers as the post-asymptotic giant branch phase, lasts only about 100,000 years -- just an eye-blink in comparison to the star's total lifetime. To better understand the process, astronomers need to study large numbers of these unusual stars.

"The UVOT's capabilities give us a great tool for surveying stellar populations and cataloging rare types of ultraviolet-bright stars," Siegel explained.

One of the first targets for the stellar survey was the giant cluster Omega Centauri, which hosts millions of stars and may be the remains of a small galaxy. Thanks to Swift's UVOT, astronomers at Goddard and Penn State have cataloged hundreds of rare stellar types in the cluster and are now comparing their properties and numbers to predictions from theoretical models describing how stars evolve.

Related Links

• Penn State's Cool UVOT Pictures gallery

• The Swift Explorer Mission iPhone app

• Young Supernovae Observed by Swift

• "Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy" (09.16.09)

• UVOT first-light images at Mullard Space Science Laboratory

• Additional Swift imagery

Francis Reddy
NASA's Goddard Space Flight Center, Greenbelt, Md.

Crab Nebula

 The Crab Nebula

Credit: ESA/Herschel/SPIRE/PACS/MESS

Large, Annotated

See this object in:
Chromoscope  -  Google Sky

Herschel has produced an intricate view of the remains of a star that died in a stellar explosion a millennium ago. It has provided further proof that the interstellar dust which lies throughout our Galaxy is created when massive stars reach the end of their lives.

The Crab Nebula lies about six and a half thousand light years away from Earth and is the remnant of a dramatic explosion, called a supernova, originally seen by Chinese Astronomers in 1054 AD. Starting out at 12-15 times more massive than the Sun, all that was left after the dramatic death of the star is a tiny, rapidly rotating neutron star and a complex network of ejected stellar material.

The Crab Nebula is well known for its intricate nature, with beautiful filamentary structures seen at visible wavelengths. Now, for the first time, thanks to Herschel’s exquisite resolution, we can see these filaments of dust in the far-infrared region of the electromagnetic spectrum. After ruling out other sources, astronomers using Herschel showed that these filaments are made of cosmic dust, lying in exactly the same place that we see the densest clumps of supernova ejecta. This provides definitive evidence that the Crab Nebula is an efficient dust factory, containing enough dust to make around 30,000-40,000 planet Earths. The dust is made of a combination of carbon and silicate materials, which are crucial for the formation of planetary systems like our own Solar System.

The Crab Nebula and surrounding area, showing the lack of contaminating dust in the foreground and background. (large image)

Previous infrared images of the Crab Nebula, using the Spitzer Space Telescope, used much shorter wavelengths and so only showed the warmer dust. Spitzer found only a tiny amount of dust, simply because it missed the massive reservoir of colder dust now known to exist. Herschel, observing at longer wavelengths, is able to detect both warm dust (shown in green/blue in the image) and also cool dust (shown as yellow/orange), some as cold as -260 Celsius. This has allowed astronomers to measure the total mass of dust for the first time.

Large amounts of dust have been seen in supernova remnants before, but the Crab Nebula is particularly exciting as it provides the the cleanest view of what is going on. Unlike many other remnants there is almost no dusty Galactic material in front of or behind the Crab Nebula, so the image is uncontaminated by material in between it and the Earth. This also allows astronomers to rule out the possibility that the dust was swept up as the shockwave expanded throughout the surrounding region.

Large amounts of dust have been seen in supernova remnants before, but the Crab Nebula is particularly exciting as it provides the the cleanest view of what is going on. Unlike many other remnants there is almost no dusty Galactic material in front of or behind the Crab Nebula, so the image is uncontaminated by material in between it and the Earth. This also allows astronomers to rule out the possibility that the dust was swept up as the shockwave expanded throughout the surrounding region.

In most supernova remnants, much of the dust is destroyed as it ploughs into the surrounding interstellar gas and dust, crushed by violent shockwaves. A final treat is that the Crab Nebula is a much kinder environment for dust grains, so the dust does not seem to be destroyed. This may be the first observed case of dust being freshly-cooked in a supernova and surviving its outward journey carried along by the shock wave. We now have definitive evidence that supernovae created the raw materials for the first solid particles, the building blocks of rocky planets and life itself, in a blink of an eye.

The Crab Nebula as seen in visible (left), showing the glow from hot, energised gas, and far-infrared (right), showing warm dust (green/blue) and cooler dust (yellow/orange) shining in the remnant. Image credit: ESA/Herschel/SPIRE/PACS/MESS (Far-IR); NASA/ESA/STScI (Visible)

Detailed Information

Object Name:  Crab Nebula (Messier 1)
Type of Object:  Supernova remnant
Image Scale:  The image is around 10 arcminutes across
Coordinates:  Right Ascension: 5h 34m 30s ; Declination: 22° 00′ 57″
Constellation:  Taurus the Bull
Instrument:  SPIRE and PACS
Wavelengths:  70 microns (blue), 160 microns(green), 250 microns (red)
Distance of Object:  6500 light years
Date of Release: 13/12/2012
Key Programme: Mass Loss from Evolved StarsS
Publication: Gomez et al. (2012) Astrophysical Journal 760 96 "A Cool Dust Factory in the Crab Nebula: A Herschel Study of the Filaments"

NASA's Fermi Spots 'Superflares' in the Crab Nebula

There are strange goings-on in the Crab Nebula. On April 12, 2011, NASA's Fermi Gamma-ray Space Telescope detected the most powerful in a series of gamma-ray flares occurring somewhere within the supernova remnant.

WASHINGTON -- The famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any flare previously seen from the object. On April 12, NASA's Fermi Gamma-ray Space Telescope first detected the outburst, which lasted six days.

The nebula is the wreckage of an exploded star that emitted light which reached Earth in the year 1054. It is located 6,500 light-years away in the constellation Taurus. At the heart of an expanding gas cloud lies what is left of the original star's core, a superdense neutron star that spins 30 times a second. With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars (also known as pulsars).

A Hubble visible light image of the Crab Nebula inset against a full-sky gamma ray map showing the location of the nebula (croshairs). Credit: NASA. Larger image

Fermi's LAT discovered a gamma-ray 'superflare' from the Crab Nebula on April 12, 2011. These images show the number of gamma rays with energies greater than 100 million electron volts from a region of the sky centered on the Crab Nebula. Both views eliminate emission form the Crab pulsar by showing the sky in between its pulses. In both images, the bright source below is the Geminga pulsar. At left, the region 20 days before the flare; at right, April 14. Credit: NASA/DOE/Fermi LAT/R. Buehler. Larger image | Larger image without captions

Apart from these pulses, astrophysicists believed the Crab Nebula was a virtually constant source of high-energy radiation. But in January, scientists associated with several orbiting observatories, including NASA's Fermi, Swift and Rossi X-ray Timing Explorer, reported long-term brightness changes at X-ray energies.

"The Crab Nebula hosts high-energy variability that we're only now fully appreciating," said Rolf Buehler, a member of the Fermi Large Area Telescope (LAT) team at the Kavli Institute for Particle Astrophysics and Cosmology, a facility jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University.

Since 2009, Fermi and the Italian Space Agency's AGILE satellite have detected several short-lived gamma-ray flares at energies greater than 100 million electron volts (eV) -- hundreds of times higher than the nebula's observed X-ray variations. For comparison, visible light has energies between 2 and 3 eV.

On April 12, Fermi's LAT, and later AGILE, detected a flare that grew about 30 times more energetic than the nebula's normal gamma-ray output and about five times more powerful than previous outbursts. On April 16, an even brighter flare erupted, but within a couple of days, the unusual activity completely faded out.

"These superflares are the most intense outbursts we've seen to date, and they are all extremely puzzling events," said Alice Harding at NASA's Goddard Space Flight Center in Greenbelt, Md. "We think they are caused by sudden rearrangements of the magnetic field not far from the neutron star, but exactly where that's happening remains a mystery."

The Crab's high-energy emissions are thought to be the result of physical processes that tap into the neutron star's rapid spin. Theorists generally agree the flares must arise within about one-third of a light-year from the neutron star, but efforts to locate them more precisely have proven unsuccessful so far.

Since September 2010, NASA's Chandra X-ray Observatory routinely has monitored the nebula in an effort to identify X-ray emission associated with the outbursts. When Fermi scientists alerted astronomers to the onset of a new flare, Martin Weisskopf and Allyn Tennant at NASA's Marshall Space Flight Center in Huntsville, Ala., triggered a set of pre-planned observations using Chandra.

"Thanks to the Fermi alert, we were fortunate that our planned observations actually occurred when the flares were brightest in gamma rays," Weisskopf said. "Despite Chandra's excellent resolution, we detected no obvious changes in the X-ray structures in the nebula and surrounding the pulsar that could be clearly associated with the flare."

Scientists hoped that NASA's Chandra X-ray Observatory would locate X-ray sources correlated to the gamma-ray flares seen by Fermi and Italy's AGILE satellites. Two observations were made during the April 2011 superflare, but there's no clear evidence of them in the Chandra images. Credit: NASA/CXC/M. Weisskopf and A. Tennant

Scientists think the flares occur as the intense magnetic field near the pulsar undergoes sudden restructuring. Such changes can accelerate particles like electrons to velocities near the speed of light. As these high-speed electrons interact with the magnetic field, they emit gamma rays.

To account for the observed emission, scientists say the electrons must have energies 100 times greater than can be achieved in any particle accelerator on Earth. This makes them the highest-energy electrons known to be associated with any cosmic source. Based on the rise and fall of gamma rays during the April outbursts, scientists estimate that the size of the emitting region must be comparable in size to the solar system.

NASA's Fermi is an astrophysics and particle physics partnership managed by NASA's Goddard Space Flight Center in Greenbelt, Md., and 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.

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

NASA Satellites Find High-Energy Surprises in 'Constant' Crab Nebula

The combined data from several NASA satellites has astonished astronomers by revealing unexpected changes in X-ray emission from the Crab Nebula, once thought to be the steadiest high-energy source in the sky.

"For 40 years, most astronomers regarded the Crab as a standard candle," said Colleen Wilson-Hodge, an astrophysicist at NASA's Marshall Space Flight Center in Huntsville, Ala., who presented the findings today at the American Astronomical Society meeting in Seattle. "Now, for the first time, we're clearly seeing how much our candle flickers."

The Crab Nebula is the wreckage of an exploded star whose light reached Earth in 1054. It is one of the most studied objects in the sky. At the heart of an expanding gas cloud lies what's left of the original star's core, a superdense neutron star that spins 30 times a second. All of the Crab's high-energy emissions are thought to be the result of physical processes that tap into this rapid spin.

This view of the Crab Nebula in visible light comes from the Hubble Space Telescope and spans 12 light-years. The supernova remnant, located 6,500 light-years away in the constellation Taurus, is among the best-studied objects in the sky. Credit: NASA/ESA/ASU/J. Hester. Larger image

For decades, astronomers have regarded the Crab's X-ray emissions as so stable that they've used it to calibrate space-borne instruments. They also customarily describe the emissions of other high-energy sources in "millicrabs," a unit derived from the nebula's output.

"The Crab Nebula is a cornerstone of high-energy astrophysics," said team member Mike Cherry at Louisiana State University in Baton Rouge, La. (LSU), "and this study shows us that our foundation is slightly askew." The story unfolded when Cherry and Gary Case, also at LSU, first noticed the Crab's dimming in observations by the Gamma-ray Burst Monitor (GBM) aboard NASA's Fermi Gamma-ray Space Telescope.

The team then analyzed GBM observations of the object from August 2008 to July 2010 and found an unexpected but steady decline of several percent at four different "hard" X-ray energies, from 12,000 to 500,000 electron volts (eV). For comparison, visible light has energies between 2 and 3 eV.

With the Crab's apparent constancy well established, the scientists needed to prove that the fadeout was real and was not an instrumental problem associated with the GBM. "If only one satellite instrument had reported this, no one would have believed it," Wilson-Hodge said.

So the team amassed data from the fleet of sensitive X-ray observatories now in orbit: NASA's Rossi X-Ray Timing Explorer (RXTE) and Swift satellites and the European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL). The results confirm a real intensity decline of about 7 percent at energies between 15,000 to 50,000 eV over two years. They also show that the Crab has brightened and faded by as much as 3.5 percent a year since 1999.

X-ray data from NASA's Fermi, RXTE, and Swift satellites and the European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) confirm that the Crab Nebula's output has declined about 7 percent in two years at energies from 15,000 to 50,000 electron volts. They also show that the Crab has brightened or faded by as much as 3.5 percent a year since 1999. Fermi's Large Area Telescope (LAT) has detected powerful gamma-ray flares (magenta lines) as well. (Image credit: NASA's Goddard Space Flight Center). Larger version -
Unlabeled version

NASA's Chandra X-ray Observatory reveals the complex X-ray-emitting central region of the Crab Nebula. This image is 9.8 light-years across. Chandra observations were not compatible with the study of the nebula's X-ray variations. Credit: NASA/CXC/SAO/F. Seward et al. Larger image

The scientists say that astronomers will need to find new ways to calibrate instruments in flight and to explore the possible effects of the inconstant Crab on past findings. A paper on the results will appear in the Feb. 1 issue of The Astrophysical Journal Letters.

Fermi's other instrument, the Large Area Telescope, has detected unprecedented gamma-ray flares from the Crab, showing that it is also surprisingly variable at much higher energies. A study of these events was published Thursday, Jan. 6, in Science Express.

The nebula's power comes from the central neutron star, which is also a pulsar that emits fast, regular radio and X-ray pulses. This pulsed emission exhibits no changes associated with the decline, so it cannot be the source. Instead, researchers suspect that the long-term changes probably occur in the nebula's central light-year, but observations with future telescopes will be needed to know for sure.

This region is dominated by four high-energy structures: an X-ray-emitting jet; an outflow of particles moving near the speed of light, called a "pulsar wind"; a disk of accumulating particles where the wind terminates; and a shock front where the wind abruptly slows.

"This environment is dominated by the pulsar's magnetic field, which we suspect is organized precariously," said Roger Blandford, who directs the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University. "The X-ray changes may involve some rearrangement of the magnetic field, but just where this happens is a mystery."

The Crab Nebula is a supernova remnant located 6,500 light-years away in the constellation Taurus.

NASA's Fermi is an astrophysics and particle physics partnership managed by NASA's Goddard Space Flight Center in Greenbelt, Md., and 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.

The GBM Instrument Operations Center is located at the National Space Science Technology Center in Huntsville, Ala. The team includes a collaboration of scientists from UAH, NASA's Marshall Space Flight Center in Huntsville, the Max Planck Institute for Extraterrestrial Physics in Germany and other institutions.

NASA Goddard manages Swift, RXTE and a guest observer facility for U.S. participation in the European Space Agency's INTEGRAL mission.

Related Link:

Download related video and visuals from NASA Goddard's Scientific Visualization Studio

Contact

Lynn Chandler
NASA's Goddard Space Flight Center, Greenbelt, Md.
301-286-2806
lynn.chandler-1@nasa.gov

Janet Anderson
NASA's Marshall Space Flight Center, Huntsville, Ala.
256-544-6162
janet.l.anderson@nasa.gov

Crab Nebula: The Crab Nebula: A Cosmic Icon

Credit X-ray: NASA/CXC/SAO/F.Seward;
Optical: NASA/ESA/ASU/J.Hester & A.Loll;
Infrared: NASA/JPL-Caltech/Univ. Minn./R.Gehrz

JPEG (416.6 kb)

Tiff (36.9 MB)

PS (15.5 MB)

More Images

Download Desktop

Zoom-In (flash)

Great Observatories Composite Image of Crab Nebula
(Runtime: 00:14)

More Animations

A star's spectacular death in the constellation Taurus was observed on Earth as the supernova of 1054 A.D. Now, almost a thousand years later, a super dense object -- called a neutron star -- left behind by the explosion is seen spewing out a blizzard of high-energy particles into the expanding debris field known as the Crab Nebula. X-ray data from Chandra provide significant clues to the workings of this mighty cosmic "generator," which is producing energy at the rate of 100,000 suns.

This composite image uses data from three of NASA's Great Observatories. The Chandra X-ray image is shown in blue, the Hubble Space Telescope optical image is in red and yellow, and the Spitzer Space Telescope's infrared image is in purple. The X-ray image is smaller than the others because extremely energetic electrons emitting X-rays radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. Along with many other telescopes, Chandra has repeatedly observed the Crab Nebula over the course of the mission's lifetime. The Crab Nebula is one of the most studied objects in the sky, truly making it a cosmic icon.

Fast Facts for Crab Nebula:

Scale: Image is 5 arcmin across
Category: Supernovas & Supernova Remnants, Neutron Stars/X-ray Binaries
Coordinates: (J2000) RA 05h 34m 32s | Dec +22° 0.0' 52.00"
Constellation: Taurus
Observation Date: 03/14/2001 and 01/27/2004
Observation Time: 11 hours 30 minutes
Obs. ID: 1997, 4607
Color Code: X-ray: Blue; Optical: Red-Yellow; Infrared: Purple
Instrument: ACIS
References: F.Seward et al 2006, ApJ, 652, 1277
Distance Estimate: About 6,000 light years