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 Chandra Image: Supernova remnant MSH 11-62

A long observation with Chandra of the supernova remnant MSH 11-62 reveals an irregular shell of hot gas, shown in red, surrounding an extended nebula of high energy X-rays, shown in blue. 

Even though scientists have yet to detect any pulsations from the central object within MSH 11-62, the structure around it has many of the same characteristics as other pulsar wind nebulas. 

The reverse shock and other, secondary shocks within MSH 11-62 appear to have begun to crush the pulsar wind nebula, possibly contributing to its elongated shape. 

Note: the orientation of this image has been rotated by 24 degrees so that north is pointed to the upper left.

Image credit:  NASA/CXC/SAO/P. Slane et al.

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.

NASA Chandra: Exoplanet WASP-18b makes star act deceptively old

A new study from NASA’s Chandra X-ray Observatory shows that a giant exoplanet, WASP-18b, is making the star that it orbits very closely act much older than it actually is. 

This artist’s illustration depicts WASP-18b and its star, which are about 330 light years away 

Credit: NASA/CXC/M. Weiss

A planet may be causing the star it orbits to act much older than it actually is, according to new data from NASA's Chandra X-ray Observatory. This discovery shows how a massive planet can affect the behavior of its parent star.

The star, WASP-18, and its planet, WASP-18b, are located about 330 light-years from Earth. WASP-18b has a mass about 10 times that of Jupiter and completes one orbit around its star in less than 23 hours, placing WASP-18b in the "hot Jupiter" category of exoplanets, or planets outside our solar system.

WASP-18b is the first known example of an orbiting planet that has apparently caused its star, which is roughly the mass of our sun, to display traits of an older star.

"WASP-18b is an extreme exoplanet," said Ignazio Pillitteri of the Istituto Nazionale di Astrofisica (INAF)-Osservatorio Astronomico di Palermo in Italy, who led the study.

"It is one of the most massive hot Jupiters known and one of the closest to its host star, and these characteristics lead to unexpected behaviour. This planet is causing its host star to act old before its time."

Pillitteri's team determined WASP-18 is between 500 million and 2 billion years old, based on theoretical models and other data.

While this may sound old, it is considered young by astronomical standards. By comparison, our sun is about 5 billion years old and thought to be about halfway through its lifetime.

Younger stars tend to be more active, exhibiting stronger magnetic fields, larger flares, and more intense X-ray emission than their older counterparts.

Magnetic activity, flaring, and X-ray emission are linked to the star's rotation, which generally declines with age.

However, when astronomers took a long look with Chandra at WASP-18 they didn't detect any X-rays.

Using established relations between the magnetic activity and X-ray emission of stars, as well as its actual age, researchers determined WASP-18 is about 100 times less active than it should be.

"We think the planet is aging the star by wreaking havoc on its innards," said co-author Scott Wolk of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

The researchers argue that tidal forces created by the gravitational pull of the massive planet, similar to those the moon has on Earth's tides, but on a much larger scale, may have disrupted the magnetic field of the star.

The strength of the magnetic field depends on the amount of convection in the star, or how intensely hot gas stirs the interior of the star.

"The planet's gravity may cause motions of gas in the interior of the star that weaken the convection," said co-author Salvatore Sciortino also of INAF-Osservatorio Astronomico di Palermo in Italy.

"This has a domino effect that results in the magnetic field becoming weaker and the star to age prematurely."

WASP-18 is particularly susceptible to this effect because its convection zone is narrower than most stars.

This makes it more vulnerable to the impact of tidal forces that tug at it.

The effect of tidal forces from the planet may also explain an unusually high amount of Lithium found in earlier optical studies of WASP-18.

Lithium is usually abundant in younger stars, but over time convection carries lithium to the hot inner regions of a star, where it is destroyed by nuclear reactions.

If there is less convection, the lithium does not circulate into the interior of the star as much, allowing more lithium to survive.

These results were published in the July issue of Astronomy and Astrophysics and are available online.

More information: For a preprint of the study results in The Astrophysical Journal, visit: arxiv.org/abs/1406.2620

Chandra & XMM-Newton Image: Detailed X-ray view of Puppis A supernova

The destructive results of a powerful supernova explosion reveal themselves in a delicate tapestry of X-ray light, as seen in this image from NASA’s Chandra X-Ray Observatory and the European Space Agency's XMM-Newton.

Image credit: NASA /CXC /IAFE /G.Dubner et al & ESA /XMM-Newton

The image shows the remains of a supernova that would have been witnessed on Earth about 3,700 years ago.

The remnant is called Puppis A, and is around 7,000 light years away and about 10 light years across.

This image provides the most complete and detailed X-ray view of Puppis A ever obtained, made by combining a mosaic of different Chandra and XMM-Newton observations.

Low-energy X-rays are shown in red, medium-energy X-rays are in green and high energy X-rays are coloured blue.

These observations act as a probe of the gas surrounding Puppis A, known as the interstellar medium.

The complex appearance of the remnant shows that Puppis A is expanding into an interstellar medium that probably has a knotty structure.

ESA XMM-Newton

Supernova explosions forge the heavy elements that can provide the raw material from which future generations of stars and planets will form.

Studying how supernova remnants expand into the galaxy and interact with other material provides critical clues into our own origins.

A paper describing these results was published in the July 2013 issue of Astronomy and Astrophysics and is available online.

The first author is Gloria Dubner from the Instituto de Astronomía y Física del Espacio in Buenos Aires in Argentina.

Elliptical galaxies: Chandra helps explain 'red and dead galaxies'

Credit: X-ray: NASA /Chandra CXC /Stanford Univ /N.Werner et al.

NASA's Chandra X-ray Observatory has shed new light on the mystery of why giant elliptical galaxies have few, if any, young stars.

This new evidence highlights the important role that supermassive black holes play in the evolution of their host galaxies.

Because star-forming activity in many giant elliptical galaxies has shut down to very low levels, these galaxies mostly house long-lived stars with low masses and red optical colours.

Astronomers have therefore called these galaxies "red and dead."

Previously it was thought that these red and dead galaxies do not contain large amounts of cold gas—the fuel for star formation, helping to explain the lack of young stars.

ESA's Herschel Space Observatory

However, astronomers have used ESA's Herschel Space Observatory to find surprisingly large amounts of cold gas in some giant elliptical galaxies.

In a sample of eight galaxies, six contain large reservoirs of cold gas.

This is the first time that astronomers have seen large quantities of cold gas in giant elliptical galaxies that are not located at the center of a massive galaxy cluster.

With lots of cold gas, astronomers would expect many stars to be forming in these galaxies, contrary to what is observed.

To try to understand this inconsistency, astronomers studied the galaxies at other wavelengths, including X-rays and radio waves.

The Chandra observations map the temperature and density of hot gas in these galaxies.

For the six galaxies containing abundant cold gas, including NGC 4636 and NGC 5044 shown here, the X-ray data provide evidence that the hot gas is cooling, providing a source for the cold gas observed with Herschel.

However, the cooling process stops before the cold gas condenses to form stars. What prevents the stars from forming?

A strong clue comes from the Chandra images. The hot gas in the center of the six galaxies containing cold gas appears to be much more disturbed than in the cold gas-free systems.

This is a sign that material has been ejected from regions close to the central black hole. These outbursts are possibly driven, in part, by clumpy, cold gas that has been pulled onto the black hole.

The outbursts dump most of their energy into the center of the galaxy, where the cold gas is located, preventing the cold gas from cooling sufficiently to form stars.

The other galaxies in the sample, NGC 1399 and NGC 4472, are also forming few if any stars, but they have a very different appearance. No cold gas was detected in these galaxies, and the hot gas in their central regions is much smoother.

Additionally, they have powerful jets of highly energetic particles, as shown in radio images from the National Science Foundation's Karl G. Jansky Very Large Array.

These jets are likely driven by hot gas falling towards the central supermassive black holes.

By pushing against the hot gas, the jets create enormous cavities that are observed in the Chandra images, and they may heat the hot, X-ray emitting gas, preventing it from cooling and forming cold gas and stars.

The centers of NGC 1399 and NGC 4472 look smoother in X-rays than the other galaxies, likely because their more powerful jets produce cavities further away from the center, where the X-ray emission is fainter, leaving their bright cores undisturbed.

More information: A paper describing these results was published on 24 February 2014 in Monthly Notices of the Royal Astronomical Society: mnras.oxfordjournals.org/content/439/3/2291 , Preprint: arxiv.org/abs/1310.5450

NASA Chandra Image: Companion star survives supernova blast

Credit X-ray: NASA /CXC /SAO /F.Seward et al; Optical: NOAO /CTIO /MCELS, DSS

When a massive star runs out fuel, it collapses and explodes as a supernova.

Although these explosions are extremely powerful, it is possible for a companion star to endure the blast.

A team of astronomers using NASA's Chandra X-ray Observatory and other telescopes has found evidence for one of these survivors.

This hardy star is in a stellar explosion's debris field, also called its supernova remnant, located in an HII region called DEM L241.

An HII region is created when the radiation from hot, young stars strips away the electrons from neutral hydrogen atoms (HI) to form clouds of ionized hydrogen (HII).

This HII region is located in the Large Magellanic Cloud, a small companion galaxy to the Milky Way.

A new composite image of DEM L241 contains Chandra data (purple) that outlines the supernova remnant.

The remnant remains hot and therefore X-ray bright for thousands of years after the original explosion occurred.

Also included in this image are optical data from the Magellanic Cloud Emission Line Survey (MCELS) taken from ground-based telescopes in Chile (yellow and cyan), which trace the HII emission produced by DEM L241.

Additional optical data from the Digitized Sky Survey (white) are also included, showing stars in the field.

R. Davies, K. Elliott, and J. Meaburn, whose last initials were combined to give the object the first half of its name, first mapped DEM L241 in 1976.

The recent data from Chandra revealed the presence of a point-like X-ray source at the same location as a young massive star within DEM L241's supernova remnant.

Astronomers can look at the details of the Chandra data to glean important clues about the nature of X-ray sources.

For example, how bright the X-rays are, how they change over time, and how they are distributed across the range of energy that Chandra observes.

In this case, the data suggest that the point-like source is one component of a binary star system.

In such a celestial pair, either a neutron star or black hole (formed when the star went supernova) is in orbit with a star much larger than our Sun.

As they orbit one another, the dense neutron star or black hole pulls material away its companion star through the wind of particles that flows away from its surface.

If this result is confirmed, DEM L241 would be only the third binary containing both a massive star and a neutron star or black hole ever found in the aftermath of a supernova.

More information: A paper describing these results is available online and was published in the November 10, 2012, issue of The Astrophysical Journal: dx.doi.org/10.1088/0004-637X/759/2/123

Chandra and XMM-Newton: Direct measurement of distant black hole's spin

Multiple images of a distant quasar known as RX J1131-1231 are visible in this combined view from Chandra (pink) and Hubble (red, green, and blue). 

Credit: NASA/CXC/Univ of Michigan/R.C.Reis et al; Optical: NASA/STSc

Astronomers have used NASA's Chandra X-ray Observatory and the European Space Agency's (ESA) XMM-Newton to show a supermassive black hole six billion light years from Earth is spinning extremely rapidly.

This first direct measurement of the spin of such a distant black hole is an important advance for understanding how black holes grow over time.

Chandra X-ray Observatory

Black holes are defined by just two simple characteristics: mass and spin.

While astronomers have long been able to measure black hole masses very effectively, determining their spins has been much more difficult.

In the past decade, astronomers have devised ways of estimating spins for black holes at distances greater than several billion light-years away, meaning we see the region around black holes as they were billions of years ago.

However, determining the spins of these remote black holes involves several steps that rely on one another.

Rubens Reis

"We want to be able to cut out the middle man, so to speak, of determining the spins of black holes across the universe," said Rubens Reis of the University of Michigan in Ann Arbor, who led a paper describing this result that was published online Wednesday in the journal Nature.

Reis and his colleagues determined the spin of the supermassive black hole that is pulling in surrounding gas, producing an extremely luminous quasar known as RX J1131-1231 (RX J1131 for short).

ESA XMM-Newton

Because of fortuitous alignment, the distortion of space-time by the gravitational field of a giant elliptical galaxy along the line of sight to the quasar acts as a gravitational lens that magnifies the light from the quasar.

Gravitational lensing, first predicted by Einstein, offers a rare opportunity to study the innermost region in distant quasars by acting as a natural telescope and magnifying the light from these sources.

Mark Reynolds

"Because of this gravitational lens, we were able to get very detailed information on the X-ray spectrum – that is, the amount of X-rays seen at different energies – from RX J1131," said co-author Mark Reynolds also of Michigan.

"This in turn allowed us to get a very accurate value for how fast the black hole is spinning."

The X-rays are produced when a swirling accretion disk of gas and dust that surrounds the black hole creates a multimillion-degree cloud, or corona near the black hole.

X-rays from this corona reflect off the inner edge of the accretion disk.

The strong gravitational forces near the black hole alter the reflected X-ray spectrum. The larger the change in the spectrum, the closer the inner edge of the disk must be to the black hole.

More information: Paper: dx.doi.org/10.1038/nature13031

NuSTAR telescope takes observes core of supernova

Cassiopeia A is among the best-studied supernova remnants. 

This image blends data from NASA's Spitzer (red), Hubble (yellow), and Chandra (green and blue) observatories. 

Credit: NASA /JPL-Caltech /STScI /CXC /SAO

Astronomers have peered for the first time into the heart of an exploding star in the final minutes of its existence.

The feat by the high-energy X-ray satellite NuSTAR provides details of the physics of the core explosion inaccessible until now, says team member Steven Boggs of UC Berkeley.

NuSTAR mapped radioactive titanium in the Cassiopeia A supernova remnant, which has expanded outward and become visible from Earth since the central star exploded in 1671.

Astronomers for the first time have peered into the heart of an exploding star in the final minutes of its existence.

The feat is one of the primary goals of NASA's NuSTAR mission, launched in June 2012 to measure high-energy X-ray emissions from exploding stars, or supernovae, and black holes, including the massive black hole at the center of our Milky Way Galaxy.

The NuSTAR team reported in this week's issue of the journal Nature the first map of titanium thrown out from the core of a star that exploded in 1671.

That explosion produced the beautiful supernova remnant known as Cassiopeia A (Cas A).

The well-known supernova remnant has been photographed by many optical, infrared and X-ray telescopes in the past, but these revealed only how the star's debris collided in a shock wave with the surrounding gas and dust and heated it up.

NuSTAR has produced the first map of high-energy X-ray emissions from material created in the actual core of the exploding star: the radioactive isotope titanium-44, which was produced in the star's core as it collapsed to a neutron star or black hole.

The energy released in the core collapse supernova blew off the star's outer layers, and the debris from this explosion has been expanding outward ever since at 5,000 kilometers per second.

Steven Boggs

"This has been a holy grail observation for high energy astrophysics for decades," said coauthor and NuSTAR investigator Steven Boggs, UC Berkeley professor and chair of physics.

"For the first time we are able to image the radioactive emission in a supernova remnant, which lets us probe the fundamental physics of the nuclear explosion at the heart of the supernova like we have never been able to do before."

"Supernovae produce and eject into the cosmos most of the elements are important to life as we know it," said UC Berkeley professor of astronomy Alex Filippenko, who was not part of the NuSTAR team.

Alex Filippenko

"These results are exciting because for the first time we are getting information about the innards of these explosions, where the elements are actually produced."

Boggs says that the information will help astronomers build three-dimensional computer models of exploding stars, and eventually understand some of the mysterious characteristics of supernovae, such as jets of material ejected by some.

Previous observations of Cas A by the Chandra X-ray telescope, for example, showed jets of silicon emerging from the star.

Fiona Harrison

"Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology.

"Our new results show how the explosion's heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating."

More information: Study paper: dx.doi.org/10.1038/nature12997

NASA Chandra observes runaway pulsar firing an extraordinary jet

Credit X-ray: NASA /CXC /ISDC /L.Pavan et al, Radio: CSIRO /ATNF /ATCA Optical: 2MASS /UMass /IPAC-Caltech /NASA /NSF

NASA's Chandra X-ray Observatory has seen a fast-moving pulsar escaping from a supernova remnant while spewing out a record-breaking jet, the longest of any object in the Milky Way galaxy, of high-energy particles.

The pulsar, a type of neutron star, is known as IGR J11014-6103.

IGR J11014-6103's peculiar behaviour can likely be traced back to its birth in the collapse and subsequent explosion of a massive star.

Originally discovered with the European Space Agency satellite INTEGRAL, the pulsar is located about 60 light-years away from the center of the supernova remnant SNR MSH 11-61A in the constellation of Carina.

Its implied speed is between 2.5 million and 5 million mph, making it one of the fastest pulsars ever observed.

Lucia Pavan

"We've never seen an object that moves this fast and also produces a jet," said Lucia Pavan of the University of Geneva in Switzerland and lead author of a paper published Tuesday in the journal Astronomy and Astrophysics.

"By comparison, this jet is almost 10 times longer than the distance between the sun and our nearest star."

The X-ray jet in IGR J11014-6103 is the longest known in the Milky Way galaxy.

In addition to its impressive span, it has a distinct corkscrew pattern that suggests the pulsar is wobbling like a spinning top.

IGR J11014-6103 also is producing a cocoon of high-energy particles that enshrouds and trails behind it in a comet-like tail.

This structure, called a pulsar wind nebula, has been observed before, but the Chandra data show that the long jet and the pulsar wind nebula are almost perpendicular to one another.

Pol Bordas

"We can see that this pulsar is moving directly away from the center of the supernova remnant based on the shape and direction of the pulsar wind nebula," said co-author Pol Bordas, from the University of Tuebingen in Germany. "The question is, why is the jet pointing off in this other direction?"

Usually, the spin axis and jets of a pulsar point in the same direction as they are moving, but IGR J11014-6103's spin axis and direction of motion are almost at right angles.

Gerd Puehlhofer

"With the pulsar moving one way and the jet going another, this gives us clues that exotic physics can occur when some stars collapse," said co-author Gerd Puehlhofer also of the University of Tuebingen.

One possibility requires an extremely fast rotation speed for the iron core of the star that exploded.

A problem with this scenario is that such fast speeds are not commonly expected to be achievable.

The supernova remnant that gave birth to IGR J11014-6013 is elongated from top-right to bottom-left in the image roughly in line with the jet's direction.

These features and the high speed of the pulsar are hints that jets could have been an important feature of the supernova explosion that formed it.

More information: arxiv.org/abs/1309.6792

NASA Chandra: Star Consumed by Medium-Sized Black Hole | Video

Just a few hundred thousand times our Sun's mass, the hungry singularity in dwarf galaxy 47 Abell 1795 munched on a nearby star for at least 6 years, while the Chandra X-ray Observatory watched. Credit: NASA/CXC/A. Hobart

NASA Chandra Image: Cassiopeia A supernova

This colourful image of Cassiopeia A, taken by the Chandra X-Ray Observatory in 2009, shows an exploded star 11,000 light-years away. 

The green ring surrounding the supernova is from the initial shock wave generated by the explosion; it measures 10 light years in diameter. 

The bright blue areas are nearly pure iron gas from the hottest part of the star.

Credit: NASA Chandra

Chandra confirm evidence of jet in Milky Way's black hole

Composite image of Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way. 

Credit: X-ray: NASA /CXC /UCLA /Z. Li et al; Radio: NRAO /VLA

Astronomers have long sought strong evidence that Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is producing a jet of high-energy particles. 

Finally they have found it, in new results from NASA's Chandra X-ray Observatory and the National Science Foundation's Very Large Array (VLA) radio telescope.

Previous studies, using a variety of telescopes, suggested there was a jet, but these reports—including the orientation of the suspected jets—often contradicted each other and were not considered definitive.

"For decades astronomers have looked for a jet associated with the Milky Way's black hole. Our new observations make the strongest case yet for such a jet," said Zhiyuan Li of Nanjing University in China, lead author of a study appearing in an upcoming edition of the Astrophysical Journal and available online now.

Jets of high-energy particles are found throughout the universe, on large and small scales. They are produced by young stars and by black holes a thousand times larger than the Milky Way's black hole.

They play important roles in transporting energy away from the central object and, on a galactic scale, in regulating the rate of formation of new stars.

"We were very eager to find a jet from Sgr A* because it tells us the direction of the black hole's spin axis.

This gives us important clues about the growth history of the black hole," said Mark Morris of the University of California at Los Angeles, a co-author of the study.

The study shows the spin axis of Sgr A* is pointing in one direction, parallel to the rotation axis of the Milky Way, which indicates to astronomers that gas and dust have migrated steadily into Sgr A* over the past 10 billion years.

If the Milky Way had collided with large galaxies in the recent past and their central black holes had merged with Sgr A*, the jet could point in any direction.

The jet appears to be running into gas near Sgr A*, producing X-rays detected by Chandra and radio emission observed by the VLA.

The two key pieces of evidence for the jet are a straight line of X-ray emitting gas that points toward Sgr A* and a shock front—similar to a sonic boom—seen in radio data, where the jet appears to be striking the gas.

Additionally, the energy signature, or spectrum, in X-rays of Sgr A* resembles that of jets coming from supermassive black holes in other galaxies.

Scientists think jets are produced when some material falling toward the black hole is redirected outward. Since Sgr A* is presently known to be consuming very little material, it is not surprising that the jet appears weak.

A jet in the opposite direction is not seen, possibly because of gas or dust blocking the line of sight from Earth or a lack of material to fuel the jet.

The region around Sgr A* is faint, which means the black hole has been quiet in the past few hundred years.

However, a separate Chandra study announced last month shows that it was at least a million times brighter before then.

"We know this giant black hole has been much more active at consuming material in the past. When it stirs again, the jet may brighten dramatically," said co-author Frederick K. Baganoff of the Massachusetts Institute of Technology in Cambridge, Mass.

More information: "Evidence for a Parsec-scale Jet from the Galactic Center Black Hole: Interaction with Local Gas," Zhiyuan Li, Mark R. Morris, and Frederick K. Baganoff. xxx.lanl.gov/abs/1310.0146

Chandra Image of NGC 6946: The 'Fireworks Galaxy'

NGC 6946 is a medium-sized, face-on spiral galaxy about 22 million light years away from Earth. 

In the past century, eight supernovas have been observed to explode in the arms of this galaxy.

Chandra observations (purple) have, in fact, revealed three of the oldest supernovas ever detected in X-rays, giving more credence to its nickname of the "Fireworks Galaxy." 

This composite image also includes optical data from the Gemini Observatory in red, yellow, and cyan. 

Image credit: X-ray: NASA/CXC/MSSL/R.Soria et al, Optical: AURA/Gemini OBs

NASA Chandra Image: Elephant Trunk Nebula

Credit: X-ray: NASA/CXC/PSU/Getman et al, Optical: DSS, Infrared: NASA/JPL-Caltech

When radiation and winds from massive young stars impact clouds of cool gas, they can trigger new generations of stars to form.

This is what may be happening in this object known as the Elephant Trunk Nebula (or its official name of IC 1396A). 

X-rays from Chandra (purple) have been combined with optical (red, green, and blue) and infrared (orange and cyan) to give a more complete picture of this source.

NASA NuSTAR delivers the X-ray goods

Artist's concept of NuSTAR on orbit. NuSTAR has a 10-m (30') mast that deploys after launch to separate the optics modules (right) from the detectors in the focal plane (left). 

Credit: NASA/JPL-Caltech

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), is giving the wider astronomical community a first look at its unique X-ray images of the cosmos.

The first batch of data from the black-hole hunting telescope was publicly available on Aug. 29, via NASA's High Energy Astrophysics Science Archive Research Center, (HEASARC).

Fiona Harrison

"We are pleased to present the world with NuSTAR's first look at the sky in high-energy X-rays with a true focusing telescope," said Fiona Harrison, the mission's principal investigator at the California Institute of Technology (Caltech), Pasadena.

The images, taken from July to August 2012, shortly after the spacecraft launched, comprise an assortment of extreme objects, including black holes near and far.

The more distant black holes are some of the most luminous objects in the universe, radiating X-rays as they ferociously consume surrounding gas.

One type of black hole in the new batch of data is a blazar, which is an active, supermassive black hole pointing a jet toward Earth.

Systems known as X-ray binaries, in which a compact object such as a neutron star or black hole feeds off a stellar companion, are also in the mix, along with the remnants of stellar blasts called supernovas.

The data set only contains complete observations. Data will be released at a later date for those targets still being observed.

"Astronomers can use these data to better understand the capabilities of NuSTAR and design future observing proposals. The first opportunity will be this fall, for joint observations with XMM-Newton," said Karl Forster of Caltech, who is leading the effort to package the data for the public.

The European Space Agency's XMM-Newton X-ray telescope, like NASA's Chandra X-ray Observatory, complements NuSTAR.

While XMM-Newton and Chandra see lower-energy X-ray light, NuSTAR is the first telescope capable of focusing high-energy X-ray light, allowing for more detailed images than were possible before.

Astronomers can compare data sets from different missions using HEASARC, which gives them a broader understanding of an object of interest.

NuSTAR's high-energy observations help scientists bridge a gap that existed previously in X-ray astronomy, and will lead to new revelations about the bizarre and energetic side of our universe.

Other NASA missions with data available via HEASARC include Chandra, Fermi, Swift, Cosmic Background Explorer (COBE), Wilkinson Microwave Anisotropy Probe (WMAP) and many more.

NASA Chandra: Astronomers discover why SMBHs consume less material

A composite image of the region around Sagittarius A* (Sgr A*), the supermassive black hole in the center of the Milky Way. 

X-ray emission from NASA's Chandra X-ray Observatory is shown in blue, and infrared emission from the Hubble Space Telescope is shown in purple and yellow. 

The inset shows a close-up view of Sgr A* in X-rays only, covering a region half a light year wide.

The diffuse emission is from hot gas captured by the black hole and being pulled inwards. 

Less than 1% of this material reaches the black hole's event horizon, or point of no return, because much of it is ejected. 

Credit: X-ray: NASA/UMass/Q.D. Wang et al.; IR: NASA/STScI

Using NASA's super-sensitive Chandra X-ray space telescope, a team of astronomers led by Q. Daniel Wang at the University of Massachusetts Amherst has solved a long-standing mystery about why most super massive black holes (SMBH) at the centers of galaxies have such a low accretion rate—that is, they swallow very little of the cosmic gases available and instead act as if they are on a severe diet.

"In principle, super massive black holes suck in everything," Wang says, "but we found this is not correct."

Astronomers once thought SMBHs with their intense gravitational pull indiscriminately devoured all sorts of stars, dust and other matter in epic amounts.

But in recent years, using X-ray emissions as a measure of heat given off by powerful gravitational forces, they unexpectedly found that most SMBH accrete matter at very low levels.

In fact, SMBHs' signature X-ray emissions, which come from an area much larger than the black holes themselves, are often so surprisingly faint that the objects are difficult to distinguish from their galaxy centers.

"There has been a big mystery about why most of these black hole signals are so faint," says Wang, an expert in deep space X-ray analysis.

Now, taking advantage of very long observation times with the Chandra instrument and their detailed knowledge of the nearest SMBH, Sagittarius A* (Sgt A*), about 26,000 light years away at the center of our own Milky Way galaxy, he and an international team of astronomers tested the leading accretion models.

For the first time, they were able to pinpoint and discriminate among X-ray sources near Sgt A* and identify exactly what the SMBH is feeding on. The advance is described in the current issue of Science.

To explain the faint X-ray signals, some astronomers had theorized that emissions from regions around SMBH had nothing to do with the black hole itself but rather with concentrations of low-mass stars associated with SMBHs.

Wang adds, "There are also a huge number of young, massive stars as well as low-mass stars near these SMBHs, so it's very crowded in the downtown area of the galaxy. Hard to tell what was going on."

This artist's illustration shows the environment around Sgr A*, the supermassive black hole found some 26,000 light years away at the center of our Galaxy. 

The red disk depicts hot gas that has been captured by the black hole and is being pulled inwards. 

The source of the hot gas is young, massive stars, shown in blue, orbiting around Sgr A*. 

The illustration also shows a large amount of material being thrown outwards, a key factor in explaining why there is so little radiation from material near black holes. 

Credit: NASA/CXC/M. Weiss

"The massive stars have extremely high winds associated with them and the winds are colliding and swirling at very high speeds, which make the gases in this environment very hot. We found that first, the SMBH has difficulty in accreting such gases.

"Second, the gases are too hot for the black hole to swallow. Instead it rejects about 99 percent of this super hot material, only letting a small amount in. This makes sense because the hotter the gases, the more difficult it is for the black hole to pull them in."

A diet of cooler gases would accrete in a more orderly fashion, but the SMBH's sphere of influence and its ability to accrete or draw in new material both decrease with increasing gas temperatures, he points out.

Wang, who did this NASA-supported work while on four-month sabbatical as a Raymond and Beverly Sackler Distinguished Visiting astronomer at the University of Cambridge, U.K., points out, "Now we have physically resolved it and for the first time we've made the connection observationally between the massive stars moving around black holes and the X-ray emitting material."

"We can definitively rule out that these X-rays are coming from a concentration of low-mass stars. We don't see the expected energy signature predicted by that scenario."

The astronomers not only detected the X-ray source, he adds, but for the first time can describe its shape, which is elongated.

"Now we know what kind of material is getting into the black hole, though exactly how it happens is still another question."

More information: "Dissecting X-Ray–Emitting Gas Around the Center of Our Galaxy," by Q.D. Wang et al Science, 2013. On Arxiv: arxiv.org/abs/1307.5845

Chandra sees eclipsing planet in X-rays

Using Chandra and XMM-Newton, astronomers have detected an exoplanet passing in front of its parent star for the first time in X-rays. 

The artist's illustration shows HD 189733b, a "hot Jupiter" that goes around its star once every 2.2 days. 

The illustration also reveals the presence of a faint red companion star in the system. 

The new X-ray observations (inset) suggest that HD 189733b has a larger atmosphere than implied by previous optical studies. 

HD 189733b is the closest hot Jupiter to Earth, making it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it. 

Credit: X-ray: NASA/CXC/SAO/K.Poppenhaeger et al; Illustration: NASA/CXC/M.Weiss

For the first time since exoplanets, or planets around stars other than the sun, were discovered almost 20 years ago, X-ray observations have detected an exoplanet passing in front of its parent star.

An advantageous alignment of a planet and its parent star in the system HD 189733, which is 63 light-years from Earth, enabled NASA's Chandra X-ray Observatory and the European Space Agency's XMM Newton Observatory to observe a dip in X-ray intensity as the planet transited the star.

"Thousands of planet candidates have been seen to transit in only optical light," said Katja Poppenhaeger of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led a new study to be published in the Aug. 10 edition of the Astrophysical Journal.

"Finally being able to study one in X-rays is important because it reveals new information about the properties of an exoplanet."

The team used Chandra to observe six transits and data from XMM Newton observations of one.

The planet, known as HD 189733b, is a hot Jupiter, meaning it is similar in size to Jupiter in our solar system but in very close orbit around its star. HD 189733b is more than 30 times closer to its star than Earth is to the sun. It orbits the star once every 2.2 days.

HD 189733b is the closest hot Jupiter to Earth, which makes it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it.

They have used NASA's Kepler space telescope to study it at optical wavelengths, and NASA's Hubble Space Telescope to confirm it is blue in colour as a result of the preferential scattering of blue light by silicate particles in its atmosphere.

The study with Chandra and XMM Newton has revealed clues to the size of the planet's atmosphere. The spacecraft saw light decreasing during the transits. The decrease in X-ray light was three times greater than the corresponding decrease in optical light.

"The X-ray data suggest there are extended layers of the planet's atmosphere that are transparent to optical light but opaque to X-rays," said co-author Jurgen Schmitt of Hamburger Sternwarte in Hamburg, Germany. "However, we need more data to confirm this idea."

The researchers also are learning about how the planet and the star can affect one another.

Astronomers have known for about a decade ultraviolet and X-ray radiation from the main star in HD 189733 are evaporating the atmosphere of HD 189733b over time. The authors estimate it is losing 100 million to 600 million kilograms of mass per second.

HD 189733b's atmosphere appears to be thinning 25 percent to 65 percent faster than it would be if the planet's atmosphere were smaller.

"The extended atmosphere of this planet makes it a bigger target for high-energy radiation from its star, so more evaporation occurs," said co-author Scott Wolk, also of CfA.

Eskimo Nebula NGC 2392: A beautiful end to a star's life

Credit: X-ray: NASA/CXC/IAA-CSIC/N.Ruiz et al, Optical: NASA/STScI

Stars like the Sun can become remarkably photogenic at the end of their life.

A good example is NGC 2392, which is located about 4,200 light years from Earth.

NGC 2392, (nicknamed the "Eskimo Nebula") is what astronomers call a planetary nebula.

This designation, however, is deceiving because planetary nebulas actually have nothing to do with planets.

The term is simply a historic relic since these objects looked like planetary disks to astronomers in earlier times looking through small optical telescopes.

Instead, planetary nebulas form when a star uses up all of the hydrogen in its core—an event our Sun will go through in about five billion years.

When this happens, the star begins to cool and expand, increasing its radius by tens to hundreds of times its original size.

Eventually, the outer layers of the star are carried away by a 50,000 kilometer per hour wind, leaving behind a hot core.

This hot core has a surface temperature of about 50,000 degrees Celsius, and is ejecting its outer layers in a much faster wind traveling six million kilometers per hour.

The radiation from the hot star and the interaction of its fast wind with the slower wind creates the complex and filamentary shell of a planetary nebula. Eventually the remnant star will collapse to form a white dwarf star.

Now days, astronomers using space-based telescopes are able to observe planetary nebulas such as NGC 2392 in ways their scientific ancestors probably could never imagine.

This composite image of NGC 2392 contains X-ray data from NASA's Chandra X-ray Observatory in purple showing the location of million-degree gas near the center of the planetary nebula.

Data from the Hubble Space Telescope show—coloured red, green, and blue—the intricate pattern of the outer layers of the star that have been ejected.

The comet-shaped filaments form when the faster wind and radiation from the central star interact with cooler shells of dust and gas that were already ejected by the star.

The observations of NGC 2392 were part of a study of three planetary nebulas with hot gas in their center.

The Chandra data show that NGC 2392 has unusually high levels of X-ray emission compared to the other two.

This leads researchers to deduce that there is an unseen companion to the hot central star in NGC 2392.

The interaction between a pair of binary stars could explain the elevated X-ray emission found there.

Meanwhile, the fainter X-ray emission observed in the two other planetary nebulas in the sample—IC 418 and NGC 6826—is likely produced by shock fronts (like sonic booms) in the wind from the central star.

A composite image of NGC 6826 was included in a gallery of planetary nebulas released in 2012.

A paper describing these results is available online and was published in the April 10th, 2013 issue of The Astrophysical Journal.