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Posts Tagged ‘Chandra’

Watching For A Black Hole To Gobble Up A Gas Cloud


Simulation. Image by ESO/MPE/Marc Schartmann

Simulation. Image by ESO/MPE/Marc Schartmann

Right now a doomed gas cloud is edging ever closer to the supermassive black hole at the center of our Milky Way galaxy. These black holes feed on gas and dust all the time, but astronomers rarely get to see mealtime in action.

Northwestern University’s Daryl Haggard has been closely watching the little cloud, called G2, and the black hole, called Sgr A*, as part of a study that should eventually help solve one of the outstanding questions surrounding black holes: How exactly do they achieve such supermassive proportions?

The closest approach between the black hole and gas cloud is predicted to occur any day now. Haggard has been using two world-class observatories, the Chandra X-ray Observatory and the Very Large Array, to gather data on this potentially spectacular encounter.

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DEM L241: Hardy Star Survives Supernova Blast


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

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 (pronounced “H-two”) 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.

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NASA’s Chandra Sees Runaway Pulsar Firing An Extraordinary Jet

February 19, 2014 2 comments

Image Credit: X-ray: NASA/CXC/ISDC/L.Pavan et al, Radio: CSIRO/ATNF/ATCA O

Image Credit: X-ray: NASA/CXC/ISDC/L.Pavan et al, Radio: CSIRO/ATNF/ATCA O

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 behavior 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.

“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.”

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Fledgling Supernova Remnant Reveals Neutron Star’s Secrets

December 6, 2013 1 comment

Image: X-ray: NASA/CXC/UW-Madison/S. Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA

Image: X-ray: NASA/CXC/UW-Madison/S. Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA

With the help of NASA’s Chandra X-ray Observatory and the Australia Telescope Compact Array, an international team of astronomers has identified the glowing wreck of a star that exploded a mere 2,500 years ago — the blink of an eye in astronomical terms.

The observations, made by a team led by UW-Madison astronomy professor Sebastian Heinz, reveal an astrophysical novelty of the Milky Way: a glowing nebula created when the star exploded and, inside of it, the collapsed core of the exploded star, a neutron star, still clinging to its former companion star. It is the only known example of such a system in our galaxy.

The new observations are reported Dec. 3 in the Astrophysical Journal and are important because they provide a unique laboratory to test key theories of stellar evolution, especially about the stage of a star’s life just after most of it has been obliterated in a supernova explosion.

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Chandra Archive Collection: Preserving The Legacy Of The X-ray Universe

October 31, 2013 Leave a comment

Every year, October is designated as American Archive Month. While many people may think “archive” means only dusty books and letters, there are, in fact, many other types of important archives. This includes the use of archives for major telescopes and observatories like NASA’s Chandra X-ray Observatory.

The Chandra Data Archive (CDA) plays a central role in the mission by enabling the astronomical community – as well as the general public – access to data collected by the observatory. The primary role of the CDA is to store and distribute data, which the CDA does with the help of powerful search engines. The CDA is one of the legacies of the Chandra mission that will serve both the scientific community and the public for decades to come.

To celebrate and support American Archive Month, we have selected images from a group of eight objects in the CDA to be released to the public for the first time. These images represent the observations of thousands of objects that are permanently available to the world thanks to Chandra’s archive.

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NASA’s Hubble And Chandra Find Evidence For Densest Nearby Galaxy

September 24, 2013 Leave a comment

The densest galaxy in the nearby part of the Universe may have been found. Packed with an extraordinary number of stars, this unusual galaxy is providing astronomers with clues to its intriguing past and how it fits into the galactic evolutionary chain.

The galaxy, known as M60-UCD1, is a type of “ultra-compact dwarf galaxy”. It was discovered with NASA’s Hubble Space Telescope and follow-up observations were done with NASA’s Chandra X-ray Observatory and ground-based optical telescopes.

Observations from the W. M. Keck Observatory on the summit of Mauna Kea, Hawaii, characterized it as the most luminous known galaxy of its type and one of the most massive, weighing 200 million times more than our Sun.

What makes M60-UCD1 so remarkable is that about half of this mass is found within a radius of only about 80 light years. This would make the density of stars about 15,000 times greater than found in Earth’s neighborhood in the Milky Way, meaning that the stars are about 25 times closer.

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NASA’s Chandra Observatory Catches Giant Black Hole Rejecting Material

August 29, 2013 Leave a comment

Astronomers using NASA’s Chandra X-ray Observatory have taken a major step in explaining why material around the giant black hole at the center of the Milky Way Galaxy is extraordinarily faint in X-rays. This discovery holds important implications for understanding black holes.

New Chandra images of Sagittarius A* (Sgr A*), which is located about 26,000 light-years from Earth, indicate that less than 1 percent of the gas initially within Sgr A*’s gravitational grasp ever reaches the point of no return, also called the event horizon. Instead, much of the gas is ejected before it gets near the event horizon and has a chance to brighten, leading to feeble X-ray emissions.

These new findings are the result of one of the longest observation campaigns ever performed with Chandra. The spacecraft collected five weeks’ worth of data on Sgr A* in 2012. The researchers used this observation period to capture unusually detailed and sensitive X-ray images and energy signatures of super-heated gas swirling around Sgr A*, whose mass is about 4 million times that of the sun.

Full Story: http://www.nasa.gov/mission_pages/chandra/news/black-hole-rejects-food.html#.UiAD9L-wUV0

NGC 1232: Dwarf Galaxy Caught Ramming Into A Large Spiral

August 15, 2013 Leave a comment

Credit: X-ray: NASA/CXC/Huntingdon Inst. for X-ray Astronomy/G.Garmire, Optical: ESO/VLT

Credit: X-ray: NASA/CXC/Huntingdon Inst. for X-ray Astronomy/G.Garmire, Optical: ESO/VLT

Observations with NASA’s Chandra X-ray Observatory have revealed a massive cloud of multimillion-degree gas in a galaxy about 60 million light years from Earth. The hot gas cloud is likely caused by a collision between a dwarf galaxy and a much larger galaxy called NGC 1232. If confirmed, this discovery would mark the first time such a collision has been detected only in X-rays, and could have implications for understanding how galaxies grow through similar collisions.

An image combining X-rays and optical light shows the scene of this collision. The impact between the dwarf galaxy and the spiral galaxy caused a shock wave – akin to a sonic boom on Earth – that generated hot gas with a temperature of about 6 million degrees. Chandra X-ray data, in purple, show the hot gas has a comet-like appearance, caused by the motion of the dwarf galaxy. Optical data from the European Southern Observatory’s Very Large Telescope reveal the spiral galaxy in blue and white. X-ray point sources have been removed from this image to emphasize the diffuse emission.

Full Story and Images: http://www.chandra.si.edu/photo/2013/ngc1232/

G1.9+0.3: The Remarkable Remains Of A Recent Supernova


Credit: X-ray (NASA/CXC/NCSU/K. Borkowski et al.); Optical (DSS)

Credit: X-ray (NASA/CXC/NCSU/K. Borkowski et al.); Optical (DSS)

Astronomers estimate that a star explodes as a supernova in our Galaxy, on average, about twice per century. In 2008, a team of scientists announced they discovered the remains of a supernova that is the most recent, in Earth’s time frame, known to have occurred in the Milky Way.

The explosion would have been visible from Earth a little more than a hundred years ago if it had not been heavily obscured by dust and gas. Its likely location is about 28,000 light years from Earth near the center of the Milky Way. A long observation equivalent to more than 11 days of observations of its debris field, now known as the supernova remnant G1.9+0.3, with NASA’s Chandra X-ray Observatory is providing new details about this important event.

The source of G1.9+0.3 was most likely a white dwarf star that underwent a thermonuclear detonation and was destroyed after merging with another white dwarf, or pulling material from an orbiting companion star. This is a particular class of supernova explosions (known as Type Ia) that are used as distance indicators in cosmology because they are so consistent in brightness and incredibly luminous.

Full Story: http://chandra.si.edu/photo/2013/g19/

NGC 6240: Colossal Hot Cloud Envelopes Colliding Galaxies


Credit: X-ray (NASA / CXC / SAO / E.Nardini et al); Optical (NASA / STScI)

Credit: X-ray (NASA / CXC / SAO / E.Nardini et al); Optical (NASA / STScI)

Scientists have used Chandra to make a detailed study of an enormous cloud of hot gas enveloping two large, colliding galaxies. This unusually large reservoir of gas contains as much mass as 10 billion Suns, spans about 300,000 light years, and radiates at a temperature of more than 7 million degrees Kelvin.

This giant gas cloud, which scientists call a “halo,” is located in the system called NGC 6240. Astronomers have long known that NGC 6240 is the site of the merger of two large spiral galaxies similar in size to our own Milky Way. Each galaxy contains a supermassive black hole at its center. The black holes are spiraling toward one another, and may eventually merge to form a larger black hole.

Another consequence of the collision between the galaxies is that the gas contained in each individual galaxy has been violently stirred up. This caused a baby boom of new stars that has lasted for at least 200 million years. During this burst of stellar birth, some of the most massive stars raced through their evolution and exploded relatively quickly as supernovas.

Full Story and Images: http://www.chandra.harvard.edu/photo/2013/ngc6240/