Posted on by Nancy Atkinson

New Movie of a Neutron Star Looks Eerily Like the Phantom of the Opera

The Vela pulsar, a neutron star that was formed when a massive star collapsed. Credit: NASA

This incredible new movie of the Vela pulsar has the unnerving appearance of the Phantom of the Opera – wearing not only a mask, but also a steam-blowing hat like the Tin Man in “The Wizard of Oz.” What you are seeing here are observations from the Chandra X-ray Observatory, showing a fast moving jet of particles produced by a rapidly rotating neutron star. Scientists say these observations may provide new insight into the nature of some of the densest matter in the universe.

The Vela pulsar is about 1,000 light-years from Earth, about 19 km (12 miles) in diameter, and makes a complete rotation in 89 milliseconds. As the pulsar whips around, it spews out a jet of charged particles that race along the pulsar’s rotation axis at about 70 percent of the speed of light. The Chandra data used in the movie were obtained from June to September 2010, and it may suggest the pulsar may be slowly wobbling, or precessing, as it spins. The period of the precession, which is analogous to the slow wobble of a spinning top, is estimated to be about 120 days.

“We think the Vela pulsar is like a rotating garden sprinkler — except with the water blasting out at over half the speed of light,” said Martin Durant of the University of Toronto in Canada, who is the first author of the paper describing these results.

The eight images shown in the movie suggest that the pulsar may be slowly wobbling, or precessing, as it spins. If the evidence for precession of the Vela pulsar is confirmed, it would be the first time that a jet from a neutron star has been found to be wobbling, or precessing, in this way.

One possible cause of precession for a spinning neutron star is that it has become slightly distorted and is no longer a perfect sphere. This distortion might be caused by the combined action of the fast rotation and “glitches”, sudden increases of the pulsar’s rotational speed due to the interaction of the superfluid core of the neutron star with its crust.

A paper describing these results will be published in The Astrophysical Journal on January 10, 2013.

This is the second Chandra movie of the Vela pulsar. The first one, released in 2003, looks like a Halloween Jack-o-lanatern gone wrong:

This movie contains shorter, unevenly spaced observations so that the changes in the jet were less pronounced and the authors did not argue that precession was occurring. However, based on the same data, Avinash Deshpande of Arecibo Observatory in Puerto Rico and the Raman Research Institute in Bangalore, India, and the late Venkatraman Radhakrishnan, argued in a 2007 paper that the Vela pulsar might be precessing.

The Earth also precesses as it spins, with a period of about 26,000 years. In the future Polaris will no longer be the “north star” and other stars will take its place. The period of the Vela precession is much shorter and is estimated to be about 120 days.

Wide field Optical and X-ray image of the supernova remnant in the Vela Pulsar region. Credit: Anglo-Australian Observatory.
Wide field Optical and X-ray image of the supernova remnant in the Vela Pulsar region. Credit: Anglo-Australian Observatory.

The supernova that formed the Vela pulsar exploded over 10,000 years ago. This optical image from the Anglo-Australian Observatory’s UK Schmidt telescope shows the enormous apparent size of the supernova remnant formed by the explosion. The full size of the remnant is about eight degrees across, or about 16 times the angular size of the Moon. The square near the center shows the Chandra image with a larger field-of-view than used for the movie, with the Vela pulsar in the middle.

A 'Phantom of the Opera' - like mask.
A 'Phantom of the Opera' - like mask.


Source: NASA

Posted on by John Williams

Combining Light to Reveal Monster Black Holes

NGC 3627 glows in the combined light of Hubble, Chandra, Spitzer and the Very Large Telescope in this image. Astronomers conducted a survey of 62 galaxies, including NGC 3627 to study monster black holes at their centers.

It’s not just pretty, it’s science. Like a starry watercolor, astronomers combining light from Earth and space-based observatories found 37 new supermassive black hole candidates lurking in nearby galaxies.

Included in that survey is NGC 3627 pictured above. Astronomers combined X-ray data from NASA’s Chandra X-ray Observatory, infrared data from the Spitzer Space Telescope, and optical data from the Hubble Space Telescope and the Very Large Telescope. The other images give the galaxy context but it’s the ghostly blue images from Chandra that show super bright in the X-ray images; X-ray light powered by material falling into a monster black hole.

Gas and dust slowly spins around the black hole creating a flattened disk, or accretion disk. As material falls inward, it heats up and releases large amounts of energy that shine brightly in the ultraviolet region of the spectrum.

NGC 3627, located about 30 million light-years from Earth, was just one of a survey of 62 nearby galaxies using archived data from Chandra and data from the Spitzer Infrared Nearby Galaxy Survey. Of those, 37 galaxies contained bright X-ray sources, indicating active black holes at their cores. Scientists believe that seven of those sources are new supermassive black hole candidates.

The paper describing the survey results was published in the April 10, 2011 issue of The Astrophysical Journal.

Combining ultraviolet and infrared observations confirm previous Chandra results that found that there may be many more galaxies powered by monster black holes than believed previously through optical surveys. Scientists say in the paper that low-levels of black hole activity previously may have been hidden by dust or washed out by the bright light of the galaxy.

Image caption: Bright X-ray sources glow a ghostly blue in this image in NGC 3627 from NASA’s Chandra X-ray Observatory. A study confirms previous Chandra results that indicate that more galaxies powered by monster black holes populate the cosmos.

Source: Chandra X-ray Observatory website

Posted on by Nancy Atkinson

Astronomers Find Ultimate Oxymoron: A Small Supermassive Black Hole

There’s jumbo shrimp and accurate rumors; now there’s even a mini supermassive black hole. Astronomers have identified the smallest supermassive black hole ever observed, and while it’s considered a shrimp as far as supermassive black holes go, this guy is still pretty big: the mass of the black hole in galaxy NGC 4178 is estimated to be about 200,000 times the mass of our Sun. But it was a surprise that this galaxy had a black hole at all.

Astronomers using the Chandra X-Ray Observatory in conjunction with other observatories took a look at NGC 4178, a late-type spiral galaxy located about 55 million light years from Earth. It does not contain a bright central concentration, or bulge, of stars in its center, and so it was thought that perhaps this galaxy was one of the few that didn’t harbor a black hole.

With using Chandra’s X-Ray vision, as well as infrared data the NASA’s Spitzer Space Telescope and radio data from the Very Large Array, Nathan Secrest, from George Mason University and his team identified a weak X-ray source at the center of the galaxy, and also saw varying brightness at infrared wavelengths, suggesting that a black hole was actually in the center of NGC 4178 and was pulling in material from its surroundings. The same data also suggested that light generated by this infalling material is heavily absorbed by gas and dust and was therefore surrounding a black hole.

They were able to estimate the size of the black hole by using the known relationship between the mass of a black hole and the amount of X-rays and radio waves it generates.

While this is the lowest mass supermassive black holes ever observed, astronomers admit this is probably near the extreme low-mass end of being in the “supermassive” range. And as the team pointed out in their paper, there is increasing evidence that several late-type galaxies do host supermassive black holes, and that a classical bulge is not a requirement for a supermassive black hole to form and grow.

Read the team’s paper.

Source: NASA

Posted on by John Williams

Blowing a Super-duper Celestial Bubble

Image credit: X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, Optical: ESO/WFI/2.2-m. Zoom by John Williams/TerraZoom using Zoomify

When NASA combines images from different telescopes, they create dazzling scenes of celestial wonder and in the process we learn a few more things. Behold this wonder of combined light, known as LHA 120-N 44, or N 44 for short. Zoom into the scene using the toolbar at the bottom of the image. Click the farthest button on the right of the toolbar to see this wonder in full-screen. (Hint: press the “Esc” key to get back to work)

Continue reading “Blowing a Super-duper Celestial Bubble”

Posted on by Jason Major

Astronomers Discover Milky Way’s Hot Halo

Artist's impression of the huge halo of hot gas surrounding the Milky Way Galaxy. Credit: NASA

Artist’s illustration of a hot gas halo enveloping the Milky Way and Magellanic Clouds (NASA/CXC/M.Weiss; NASA/CXC/Ohio State/A.Gupta et al.)

Our galaxy — and the nearby Large and Small Magellanic Clouds as well — appears to be surrounded by an enormous halo of hot gas, several hundred times hotter than the surface of the Sun and with an equivalent mass of up to 60 billion Suns, suggesting that other galaxies may be similarly encompassed and providing a clue to the mystery of the galaxy’s missing baryons.

The findings were reported today by a research team using data from NASA’s Chandra X-ray Observatory.

In the artist’s rendering above our Milky Way galaxy is seen at the center of a cloud of hot gas. This cloud has been detected in measurements made with Chandra as well as with the European Space Agency’s XMM-Newton space observatory and Japan’s Suzaku satellite. The illustration shows it to extend outward over 300,000 light-years — and it may actually be even bigger than that.

While observing bright x-ray sources hundreds of millions of light-years distant, the researchers found that oxygen ions in the immediate vicinity of our galaxy were “selectively absorbing” some of the x-rays. They were then able to measure the temperature of the halo of gas responsible for the absorption.

The scientists determined the temperature of the halo is between 1 million and 2.5 million kelvins — a few hundred times hotter than the surface of the Sun.

But even with an estimated mass anywhere between 10 billion and 60 billion Suns, the density of the halo at that scale is still so low that any similar structure around other galaxies would escape detection. Still, the presence of such a large halo of hot gas, if confirmed, could reveal where the missing baryonic matter in our galaxy has been hiding — a mystery that’s been plaguing astronomers for over a decade.

Unrelated to dark matter or dark energy, the missing baryons issue was discovered when astronomers estimated the number of atoms and ions that would have been present in the Universe 10 billion years ago. But current measurements yield only about half as many as were present 10 billion years ago, meaning somehow nearly half the baryonic matter in the Universe has since disappeared.

Recent studies have proposed that the missing matter is tied up in the comic web — vast clouds and strands of gas and dust that surround and connect galaxies and galactic clusters. The findings announced today from Chandra support this, and suggest that the missing ions could be gathered around other galaxies in similarly hot halos.

Even though previous studies have indicated halos of warm gas existing around our galaxy as well as others, this new research shows a much hotter, much more massive halo than ever detected.

“Our work shows that, for reasonable values of parameters and with reasonable assumptions, the Chandra observations imply a huge reservoir of hot gas around the Milky Way,” said study co-author Smita Mathur of Ohio State University in Columbus. “It may extend for a few hundred thousand light-years around the Milky Way or it may extend farther into the surrounding local group of galaxies. Either way, its mass appears to be very large.”

Read the full news release from NASA here, and learn more about the Chandra mission here. (The team’s paper can be found on arXiv.org.)

Inset image: NASA’s Chandra spacecraft (NASA/CXC/NGST)

NOTE: the initial posting of this story mentioned that this halo could be dark matter. That was incorrect and not implied by the actual research, as dark matter is non-baryonic matter while the hot gas in the halo is baryonic — i.e., “normal” —  matter. Edited. – JM

Posted on by John Williams

The Unusually Colossal Kepler Supernova

A composite image of Chandra X-ray data shows a rainbow of reds, yellows, green, blue and purple, from lower to higher energies. Optical data from the Digitized Sky Survey, shown in pale yellow and blue, offer a starry background for the image. Optical: DSS

An arc of hot gas that spewed from the Kepler Supernova offers tantalizing clues that the cataclysmic stellar explosion of 1604 was not only more powerful than previously thought but also farther away according to a recent study using Chandra X-ray Observatory data published in the September 1, 2012 edition of The Astrophysical Journal.

A new star appeared in the autumn skies of 1604. Although it was described by other astronomers, it was famous astronomer Johannes Kepler who thoroughly detailed the the second supernova sighting in a generation. The star shined more brilliant than Jupiter and remained visible – even during the day – over several weeks.

Look for Kepler’s Supernova at the foot of the constellation Ophiuchus, the Serpent Bearer, in visible light and you won’t see much. But the hot gas and dust glow brightly in the X-ray images from Chandra. Astronomers have long puzzled over Kepler’s Supernova. Astronomers now know the explosion that created the remnant was a Type Ia supernova. Supernovae of this class occur when a white dwarf, the white-hot dead core of a once Sun-like star, gains mass by either merging with another white dwarf or drawing gas onto its surface from a larger companion star until temperatures soar and thermonuclear processes spiral out of control resulting in a detonation that destroys the star.

Kepler’s Supernova is a bit different because the expanding debris cloud is shaped by gas and dust clouds throughout the area. Most Type Ia supernovae are symmetrical; nearly perfect expanding bubbles of material. A quick look at the Chandra image of the supernova and one notices the bright arc of material across the top edge of shockwave. In one model, a pre-supernova white dwarf and its companion were moving through a nebulous area creating a bow shock, like a boat plowing through water, in front. Another model suggests that the glowing arc is the edge of the supernova shockwave as it passes through an area of increasingly dense gas and dust. Both models push the distance of the supernova from the previously believed 13,000 light-years to more than 20,000 light-years from Earth, scientists say in the paper.

Scientists also found large amounts of iron by looking at the X-ray light from Chandra meaning that the explosion was far more powerful than an average Type Ia supernova. Astronomers have observed a similar Type Ia supernova using Chandra and an optical telescope in the Large Magellanic Cloud.

Kepler’s Supernova is the last Milky Way supernova visible to the naked eye. It was the second supernova to be observed in that generation after SN 1572 in Cassiopeia studied by the famous astronomer Tycho Brahe.

Source: http://chandra.harvard.edu

About the author: John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines. Follow John on Twitter @terrazoom.

Posted on by Jason Major

Pulsar Sets New Speed Record

A pulsar may have been spotted racing through space at over 6 million miles per hour (9.65 million km/h), setting a new speed record for these curious cosmic objects. If observations are what they appear to be, astronomers will have to recalculate the incredible forces created by supernova explosions.

Seen in observations made with 3 different telescopes — NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, and the Parkes radio telescope in Australia — the x-ray-emitting object IGR J11014-6103 appears to be racing away from the remnants of a supernova in the constellation Carina, 30,000 light-years from Earth.

The comet-shaped object is thought to be a pulsar, the rapidly-spinning, superdense remains of a star. The facts that it’s dim in optical and infrared wavelengths and hasn’t changed in x-ray brightness between XMM-Newton observations in 2003 and Chandra measurements in 2011 support the claim.

IGR J11014’s comet-like shape may be the result of its breakneck speed through space as its pulsar wind nebula gets blown back by the high-energy bow shock created at the forefront of its passage.

Pulsar wind nebulae are the results of charged particles streaming out from the pulsar itself. The particles, traveling at nearly light-speed, are rapidly decelerated by the interstellar medium and create a visible shock wave. In the case of IGR J11014, the pulsar wind is formed into a “tail” by its bow shock — effectively a sonic boom in front of it.

Further observations will be needed to confirm that IGR J11014 is indeed a pulsar, especially considering that actual pulsations have not yet been detected. If it is a pulsar, and is really traveling at the record-breaking speeds it appears to be — between 5.4 and 6.5 million miles per hour, more than 12 times faster than the Sun travels around the center of the galaxy — a new model of supernova explosions may be required.

Read more on the Chandra news release here.

Image: X-ray: NASA/CXC/UC Berkeley/J.Tomsick et al & ESA/XMM-Newton, Optical: DSS; IR: 2MASS/UMass/IPAC-Caltech/NASA/NSF. Video: NASA/CXC/A. Hobart.

Posted on by Nancy Atkinson

Black Hole Growth Out of Whack in Some Galaxies

Galaxies NGC 4342 and NGC 4291. (X-ray: NASA/CXC/SAO/A.Bogdan et al; Infrared: 2MASS/UMass/IPAC-Caltech/ NASA/NSF)

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From a Chandra press release:

New evidence from NASA’s Chandra X-ray Observatory challenges prevailing ideas about how black holes grow in the centers of galaxies. Astronomers long have thought that a supermassive black hole and the bulge of stars at the center of its host galaxy grow at the same rate — the bigger the bulge, the bigger the black hole. However, a new study of Chandra data has revealed two nearby galaxies with supermassive black holes that are growing faster than the galaxies themselves.

The mass of a giant black hole at the center of a galaxy typically is a tiny fraction — about 0.2 percent — of the mass contained in the bulge, or region of densely packed stars, surrounding it. The targets of the latest Chandra study, galaxies NGC 4342 and NGC 4291, have black holes 10 times to 35 times more massive than they should be compared to their bulges. The new observations with Chandra show the halos, or massive envelopes of dark matter in which these galaxies reside, also are overweight.

This study suggests the two supermassive black holes and their evolution are tied to their dark matter halos and did not grow in tandem with the galactic bulges. In this view, the black holes and dark matter halos are not overweight, but the total mass in the galaxies is too low.

“This gives us more evidence of a link between two of the most mysterious and darkest phenomena in astrophysics — black holes and dark matter — in these galaxies,” said Akos Bogdan of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the new study.

NGC 4342 and NGC 4291 are close to Earth in cosmic terms, at distances of 75 million and 85 million light years. Astronomers had known from previous observations that these galaxies host black holes with relatively large masses, but are not certain what is responsible for the disparity. Based on the new Chandra observations, however, they are able to rule out a phenomenon known as tidal stripping.

Tidal stripping occurs when some of a galaxy’s stars are stripped away by gravity during a close encounter with another galaxy. If such tidal stripping had taken place, the halos mostly would have been missing. Because dark matter extends farther away from the galaxies, it is more loosely tied to them than the stars and more likely to be pulled away.

To rule out tidal stripping, astronomers used Chandra to look for evidence of hot, X-ray-emitting gas around the two galaxies. Because the pressure of hot gas — estimated from X-ray images — balances the gravitational pull of all the matter in the galaxy, the new Chandra data can provide information about the dark matter halos. The hot gas was found to be distributed widely around NGC 4342 and NGC 4291, implying that each galaxy has an unusually massive dark matter halo and that tidal stripping is unlikely.

“This is the clearest evidence we have, in the nearby universe, for black holes growing faster than their host galaxy,” said co-author Bill Forman, also of CfA. “It’s not that the galaxies have been compromised by close encounters, but instead they had some sort of arrested development.”

How can the mass of a black hole grow faster than the stellar mass of its host galaxy? The study’s authors suggest a large concentration of gas spinning slowly in the galactic center is what the black hole consumes very early in its history. It grows quickly, and as it grows, the amount of gas it can accrete, or swallow, increases along with the energy output from the accretion. After the black hole reaches a critical mass, outbursts powered by the continued consumption of gas prevent cooling and limit the production of new stars.

“It’s possible that the supermassive black hole reached a hefty size before there were many stars at all in the galaxy,” said Bogdan. “That is a significant change in our way of thinking about how galaxies and black holes evolve together.”

The results were presented June 11 at the 220th meeting of the American Astronomical Society in Anchorage, Alaska. The study also has been accepted for publication in The Astrophysical Journal.

Posted on by Nancy Atkinson

Are Rogue Black Holes Wandering the Universe?

A composite image of galaxy CID-4 shows evidence the black hole is being ejected. Credit: X-ray: NASA/CXC/SAO/F.Civano et al; Optical: NASA/STScI; Optical (wide field): CFHT, NASA/STScI

Talk about a tough neighborhood! Even black holes aren’t welcome in galaxy CID-42, located about 4 billion light-years away from Earth. Astronomers using the Chandra X-Ray Observatory have found strong evidence that a massive black hole is being ejected from this galaxy, moving out at a speed of several million kilometers per hour. This phenomenon, known as a recoiled black hole, happens due to a gravitational wave “kick” from the merger of two black holes.

While this event is likely to be rare, it could mean that there could be giant black holes roaming undetected out in the vast spaces between galaxies.
Continue reading “Are Rogue Black Holes Wandering the Universe?”

Posted on by Nancy Atkinson

Chandra Witnesses Big Blast from an Old Black Hole

Before and After Images in X-ray and Optical Light In Chandra observations that spanned several years, the ULX in M83 increased in X-ray brightness by at least 3,000 times. This sudden brightening is one of the largest changes in X-rays ever seen for this type of object, which do not usually show dormant periods. (Credit: Optical: ESO/VLT; Close-up - X-ray: NASA/CXC/Curtin University/R.Soria et al., Optical: NASA/STScI/Middlebury College/F.Winkler et al.)

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Astronomers keeping an eye out for a supernova explosion in the nearby galaxy M83 instead witnessed a prodigious blast of another type: a new ultraluminous X-ray source, or ULX. In what scientists are calling an “extraordinary outburst,” the ULX in M83 increased in X-ray brightness by at least 3,000 times, one of the largest changes in X-rays ever seen for this type of object.

“The flaring up of this ULX took us by surprise and was a sure sign we had discovered something new about the way black holes grow,” said Roberto Soria of Curtin University in Australia, who led the new study.

The researchers say this blast provides direct evidence for a population of old, volatile stellar black holes and gives new insight into the nature of a mysterious class of black holes that can produce as much energy in X-rays as a million suns radiate at all wavelengths.

Astrophysicist Bill Blair of Johns Hopkins University, writing in the Chandra Blog, “A Funny Thing Happened While Waiting for the Next Supernova in M83,” said this galaxy, also known as the Southern Pinwheel Galaxy, “is an amazing gift of nature. At 15 million light years away, it is actually one of the closer galaxies (only 7-8 times more distant than the Andromeda galaxy), but it appears as almost exactly face-on, giving earthlings a fantastic view of its beautiful spiral arms and active star-forming nucleus.”

M83 has generated six observed supernovas since 1923, but the last one seen was in 1983. “We are overdue for a new supernova!” Blair wrote.

So, many astronomers have been observing M83, hoping to spot a new supernova, but instead saw a dramatic jump in X-ray brightness, which according to the researchers, likely occurred because of a sudden increase in the amount of material falling into the black hole.

A ULX can give off more X-rays than most “normal” binary systems in which a companion star is in orbit around a neutron star or black hole. The super-sized X-ray emission suggests ULXs contain black holes that might be much more massive than the ones found elsewhere in our galaxy.

Composite image of spiral galaxy M83. (X-ray: NASA/CXC/Curtin University/R. Soria et al., Optical: NASA/STScI/ Middlebury College/F. Winkler et al.)

The companion stars to ULXs, when identified, are usually young, massive stars, implying their black holes are also young. The latest research, however, provides direct evidence that ULXs can contain much older black holes and some sources may have been misidentified as young ones.

The observations of M83 were made over a several year period with Chandra. No sign of the ULX was found in historical X-ray images made with Einstein Observatory in 1980, ROSAT in 1994, the European Space Agency’s XMM-Newton in 2003 and 2008, NASA’s Swift observatory in 2005, the Magellan Telescope observations in April 2009 or in a Hubble image obtained in August 2009.

But in 2011, Soria and his colleagues used optical images from the Gemini Observatory and NASA’s Hubble Space Telescope and saw a bright blue source at the position of the X-ray source.

The lack of a blue source in the earlier images indicates the black hole’s companion star is fainter, redder and has a much lower mass than most of the companions that previously have been directly linked to ULXs. The bright, blue optical emission seen in 2011 must have been caused by a dramatic accumulation of more material from the companion star.

“If the ULX only had been observed during its peak of X-ray emission in 2010, the system easily could have been mistaken for a black hole with a massive, much younger stellar companion, about 10 to 20 million years old,” said co-author Blair.

The companion to the black hole in M83 is likely a red giant star at least 500 million years old, with a mass less than four times the sun’s. Theoretical models for the evolution of stars suggest the black hole should be almost as old as its companion.

Another ULX containing a volatile, old black hole recently was discovered in the Andromeda galaxy by a team led by Amanpreet Kaur from Clemson University, published in the February 2012 issue of Astronomy and Astrophysics. Matthew Middleton and colleagues from the University of Durham reported more information in the March 2012 issue of the Monthly Notices of the Royal Astronomical Society. They used data from Chandra, XMM-Newton and HST to show the ULX is highly variable and its companion is an old, red star.

“With these two objects, it’s becoming clear there are two classes of ULX, one containing young, persistently growing black holes and the other containing old black holes that grow erratically,” said Kip Kuntz, a co-author of the new M83 paper, also of Johns Hopkins University. “We were very fortunate to observe the M83 object at just the right time to make the before and after comparison.”

A paper describing these results will appear in the May 10th issue of The Astrophysical Journal.

Sources: NASA, Chandra Blog