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The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.

"If this galaxy wasn't so close, we'd have no chance of separating the two black holes the way we have," said Pepi Fabbiano of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the study that appears in this week's online issue of the journal Nature. "Since this galaxy was right under our noses by cosmic standards, it makes us wonder how many of these black hole pairs we've been missing."

Previous observations in X-rays and at other wavelengths indicated that a single supermassive black hole existed in the center of NGC 3393. However, a long look by Chandra allowed the researchers to detect and separate the dual black holes. Both black holes are actively growing and emitting X-rays as gas falls towards them and becomes hotter.

When two equal-sized spiral galaxies merge, astronomers think it should result in the formation of a black hole pair and a galaxy with a disrupted appearance and intense star formation. A well-known example is the pair of supermassive black holes in NGC 6240, which is located about 330 million light years from Earth.

However, NGC 3393 is a well-organized spiral galaxy, and its central bulge is dominated by old stars. These are unusual properties for a galaxy containing a pair of black holes. Instead, NGC 3393 may be the first known instance where the merger of a large galaxy and a much smaller one, dubbed a "minor merger" by scientists, has resulted in the formation of a pair of supermassive black holes. In fact, some theories say that minor mergers should be the most common way for black hole pairs to form, but good candidates have been difficult to find because the merged galaxy is expected to look so typical.

"The two galaxies have merged without a trace of the earlier collision, apart from the two black holes," said co-author Junfeng Wang, also from CfA. "If there was a mismatch in size between the two galaxies it wouldn't be a surprise for the bigger one to survive unscathed."

If this was a minor merger, the black hole in the smaller galaxy should have had a smaller mass than the other black hole before their host galaxies started to collide. Good estimates of the masses of both black holes are not yet available to test this idea, although the observations do show that both black holes are more massive than about a million suns. Assuming a minor merger occurred, the black holes should eventually merge after about a billion years.

Both of the supermassive black holes are heavily obscured by dust and gas, which makes them difficult to observe in optical light. Because X-rays are more energetic, they can penetrate this obscuring material. Chandra's X-ray spectra show clear signatures of a pair of supermassive black holes.

The NGC 3393 discovery has some similarities to a possible pair of supermassive black holes found recently by Julia Comerford of the University of Texas at Austin, also using Chandra data. Two X-ray sources, which may be due to supermassive black holes in a galaxy about two billion light years from Earth, are separated by about 6,500 light years. As in NGC 3393, the host galaxy shows no signs of disturbance or extreme amounts of star formation. However, no structure of any sort, including spiral features, is seen in the galaxy. Also, one of the sources could be explained by a jet, implying only one supermassive black hole is located in the galaxy.

"Collisions and mergers are one of the most important ways for galaxies and black holes to grow," said co-author Guido Risaliti of CfA and the National Institute for Astrophysics in Florence, Italy. "Finding a black hole pair in a spiral galaxy is an important clue in our quest to learn how this happens."

NASA's Marshall Space Flight Center in Huntsville, Ala., 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.

The Chandra image  contains a bright X-ray source in the middle, which reveals the position of the supermassive black hole. An optical view of the galaxy from the European Space Observatory's Very Large Telescope shows the context of the Chandra data.

NGC 1365 contains a so-called active galactic nucleus, or AGN. Scientists believe that the black hole at the center of the AGN is fed by a steady stream of material, presumably in the form of a disk.

Material just about to fall into a black hole should be heated to millions of degrees before passing over the event horizon, or point of no return. The process causes the disk of gas around the central black hole in NGC 1365 to produce copious X-rays, but the structure is much too small to resolve directly with a telescope.

However, astronomers were able to measure the disk's size by observing how long it took for the black hole to go in and out of the eclipse. This was revealed during a series of observations of NGC 1365 obtained every two days over a period of two weeks in April 2006. During five of the observations, high-energy X-rays from the central X-ray source were visible, but in the second one -- corresponding to the eclipse -- they were not.

By measuring a peak in the temperature of hot gas in the center of the giant elliptical galaxy NGC 4649, scientists have determined the mass of the galaxy's supermassive black hole. The method, applied for the first time, gives results that are consistent with a traditional technique.

Astronomers have been seeking out different, independent ways of precisely weighing the largest supermassive black holes, that is, those that are billions of times more massive than the Sun. Until now, methods based on observations of the motions of stars or of gas in a disk near such large black holes had been used.

"This is tremendously important work since black holes can be elusive, and there are only a couple of ways to weigh them accurately," said Philip Humphrey of the University of California at Irvine, who led the study. "It's reassuring that two very different ways to measure the mass of a big black hole give such similar answers."

NGC 4649 is now one of only a handful of galaxies for which the mass of a supermassive black hole has been measured with two different methods. In addition, this new X-ray technique confirms that the supermassive black hole in NGC 4649 is one of the largest in the local universe with a mass about 3.4 billion times that of the Sun, about a thousand times bigger than the black hole at the center of our galaxy.

The new technique takes advantage of the gravitational influence the black hole has on the hot gas near the center of the galaxy. As gas slowly settles towards the black hole, it gets compressed and heated. This causes a peak in the temperature of the gas right near the center of the galaxy. The more massive the black hole, the bigger the temperature peak detected by Chandra.

This effect was predicted by two of the co-authors -- Fabrizio Brighenti from the University of Bologna, Italy, and William Mathews from the University of California at Santa Cruz -- almost 10 years ago, but this is the first time it has been seen and used.

"It was wonderful to finally see convincing evidence of the effects of the huge black hole that we expected," said Brighenti. "We were thrilled that our new technique worked just as well as the more traditional approach for weighing the black hole."

The black hole in NGC 4649 is in a state where it does not appear to be rapidly pulling in material towards its event horizon, nor generating copious amounts of light as it grows. So, the presence and mass of the central black hole has to be studied more indirectly by tracking its effects on stars and gas surrounding it. This technique is well suited to black holes in this condition.

"Monster black holes like this one power spectacular light shows in the distant, early universe, but not in the local universe," said Humphrey. "So, we can't wait to apply our new method to other nearby galaxies harboring such inconspicuous black holes."

These results will appear in an upcoming issue of The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass

Quantum computers have superior qualities in comparison to the type of computers currently in use. If they are realised, then quantum computers will be able to carry out tasks that are beyond the abilities of all normal computers.

A quantum computer is based on the amazing properties of quantum systems. In these a quantum bit, also known as a qubit, exists in two states at the same time and the information from two qubits is entangled in a way that has no equivalent whatsoever in the normal world.

It is highly likely that workable quantum computers will need to be produced using existing manufacturing techniques from the chip industry. Working on this basis, scientists at Delft University of Technology are currently studying two types of qubits: one type makes use of tiny superconducting rings, and the other makes use of 'quantum dots'.

Now for the first time a 'controlled-NOT' calculation with two qubits has been realised with the superconducting rings. This is important because it allows any given quantum calculation to be realised.

The result was achieved by the PhD student Jelle Plantenberg in the team led by Kees Harmans and Hans Mooij. The research took place within the FOM (Dutch Foundation for Fundamental Research on Matter) concentration group for Solid State Quantum Information Processing.

This elegant technique, which Titarchuk first suggested in 1998, shows that the black hole in a binary system known as Cygnus X-1 contains 8.7 times the mass of our sun, with a margin of error of only 0.8 solar mass.

Cygnus X-1 was the first compelling black hole candidate to emerge in the early 1970s. The system consists of a blue supergiant star and a massive but invisible companion. Optical observations of the star’s wobble have suggested that the invisible object is a black hole containing about 10 solar masses. "This agreement gives us a lot of confidence that our method works," says Shaposhnikov.

"Our method can determine a black hole’s mass when alternative techniques fail," adds Titarchuk, who is also a research professor at George Mason University, Arlington, Va., also works at the Naval Research Laboratory, Washington. Shaposhnikov works for the Universities Space Research Association, a part of the Center for Research and Exploration in Space Science and Technology within NASA Goddard.

Working independently, Tod Strohmayer and Richard Mushotzky of Goddard and four colleagues used Titarchuk’s technique to estimate that an ultra-luminous X-ray source in the small, nearby galaxy NGC 5408 harbors a black hole with a mass of about 2,000 suns.

"This is one of the best indications to date for an intermediate-mass black hole," says Strohmayer. This type of black hole fills in a huge gap between black holes such as Cygnus X-1, which come from collapsing massive stars and contain perhaps 5 to 20 solar masses, and monster black holes containing millions or even billions of solar masses, which lurk in the cores of large galaxies.

Titarchuk’s method takes advantage of a relationship between a black hole and the surrounding disk of matter spiraling into it, called an accretion disk. Gas orbiting in these disks eventually falls into the black hole. When a black hole’s accretion rate increases to a high level, material piles up near the black hole in a hot region that Titarchuk likens to a traffic jam. Titarchuk has shown that the distance from the black hole where this congestion occurs is on a direct scale with the mass of the black hole. The more massive the black hole, the farther this congestion occurs from the black hole, and the longer the orbital period.

In his model, hot gas piling up in the congestion region is linked to observations of X-ray intensity variations that repeat on a nearly but not perfectly periodic basis. These quasi-periodic oscillations (QPOs) are observed in many black hole systems. The QPOs are accompanied by simple, predictable changes in the system’s spectrum as the surrounding gas heats and cools in response to the changing accretion rate. Precise timing observations from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite have shown a tight relationship between the frequency of QPOs and the spectrum, telling astronomers how efficiently the black hole is producing X-ray radiation.

Using RXTE, Shaposhnikov and Titarchuk have applied this method to three stellar-mass black holes in our Milky Way Galaxy, and showed that the derived masses from the QPOs concur with mass measurements from other techniques. The paper outlining their results is scheduled to appear in the July 1 issue of Astrophysical Journal.

Using the European Space Agency’s XMM-Newton X-ray observatory, Strohmayer, Mushotzky, and their colleagues detected two QPOs in NGC 5408 X-1. This object is the brightest X-ray source in the irregular galaxy NGC 5408, 16 million light-years from Earth in the constellation Centaurus. The QPO frequencies, as well as the luminosity and spectral characteristics of the source, implies that it is powered by an intermediate-mass black hole.

"We had two other ways of estimating the mass of the black hole, and all three methods agree within a factor of two," says Mushotzky. "We don’t have proof this is an intermediate-mass black hole, but the preponderance of evidence suggests that it is."

The existence of IMBHs remains controversial because there is no widely accepted mechanism for how they could form. One of the study’s co-authors, Roberto Soria of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. thinks the black hole’s mass could be closer to 100 suns.

New research shows that some old stars might be held up by their rapid spins, and when they slow down, they explode as supernovae. Thousands of these "time bombs" could be scattered throughout our Galaxy.

"We haven't found one of these 'time bomb' stars yet in the Milky Way, but this research suggests that we've been looking for the wrong signs. Our work points to a new way of searching for supernova precursors," said astrophysicist Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics (CfA).

The specific type of stellar explosion Di Stefano and her colleagues studied is called a Type Ia supernova. It occurs when an old, compact star known as a white dwarf destabilizes.

A white dwarf is a stellar remnant that has ceased nuclear fusion. It typically can weigh up to 1.4 times as much as our Sun -- a figure called the Chandrasekhar mass after the astronomer who first calculated it. Any heavier, and gravity overwhelms the forces supporting the white dwarf, compacting it and igniting runaway nuclear fusion that blows the star apart.

There are two possible ways for a white dwarf to exceed the Chandrasekhar mass and explode as a Type Ia supernova. It can accrete gas from a donor star, or two white dwarfs can collide. Most astronomers favor the first scenario as the more likely explanation. But we would expect to see certain signs if the theory is correct, and we don't for most Type Ia supernovae.

For example, we should detect small amounts of hydrogen and helium gas near the explosion, but we don't. That gas would come from matter that wasn't accreted by the white dwarf, or from the disruption of the companion star in the explosion. Astronomers also have looked for the donor star after the supernova faded from sight, without success.

Di Stefano and her colleagues suggest that white dwarf spin might solve this puzzle. A spin-up/spin-down process would introduce a long delay between the time of accretion and the explosion. As a white dwarf gains mass, it also gains angular momentum, which speeds up its spin. If the white dwarf rotates fast enough, its spin can help support it, allowing it to cross the 1.4-solar-mass barrier and become a super-Chandrasekhar-mass star.

Once accretion stops, the white dwarf will gradually slow down. Eventually, the spin isn't enough to counteract gravity, leading to a Type Ia supernova.

"Our work is new because we show that spin-up and spin-down of the white dwarf have important consequences. Astronomers therefore must take angular momentum of accreting white dwarfs seriously, even though it's very difficult science," explained Di Stefano.

The spin-down process could produce a time delay of up to a billion years between the end of accretion and the supernova explosion. This would allow the companion star to age and evolve into a second white dwarf, and any surrounding material to dissipate.

In our Galaxy, scientists estimate that there are three Type Ia supernovae every thousand years. If a typical super-Chandrasekhar-mass white dwarf takes millions of years to spin down and explode, then calculations suggest that there should be dozens of pre-explosion systems within a few thousand light-years of Earth.

Those supernova precursors will be difficult to detect. However, upcoming wide-field surveys conducted at facilities like Pan-STARRS and the Large Synoptic Survey Telescope should be able to spot them.

"We don't know of any super-Chandrasekhar-mass white dwarfs in the Milky Way yet, but we're looking forward to hunting them out," said co-author Rasmus Voss of Radboud University Nijmegen, The Netherlands. The research appears in the Astrophysical Journal.

This result gives a surprising new twist to one of the great mysteries about black holes.

Conventional (classical) information can vanish in two ways, either by moving to another place (e.g. across the internet), or by "hiding", such as in a coded message. The famous Vernam cipher devised in 1917 or its relative the one-time pad cryptographic code are examples of such classical information hiding: the information resides neither in the encoded message nor in the secret key pad used to decipher it - but in correlations between the two.

For decades, physicists believed that both these mechanisms were applicable to quantum information as well, but Professor Braunstein and Dr Pati have demonstrated that if quantum information disappears from one place, it must have moved somewhere else.

In a paper published in the latest edition of Physical Review Letters, Braunstein and Pati derive their ‘no-hiding theorem’ and use it to study black holes which, in Einstein’s Theory of Relativity, are characterized as swallowing up anything that comes too close.

In the mid 1970s, Stephen Hawking showed that black holes eventually evaporate away in a steady stream of featureless radiation containing no information. But if a black hole has completely evaporated, where has the information about it gone? This long standing question is known as the black hole information paradox.

Now, Professor Braunstein and Dr Pati have ruled out the possibility that information might escape from the black hole but be somehow hidden in correlations between the Hawking radiation and the black hole’s internal state. Braunstein and Pati’s result demonstrates that the black hole information paradox is even more severe than previously believed.

Dr Pati said: "Our result shows that either quantum mechanics or Hawking’s analysis must break down, but it does not choose between these two possibilities."

Professor Braunstein said: "The no-hiding theorem provides new insight into the different laws governing classical and quantum information. It shows that there’s got to be new physics out there."

Three exceptionally luminous supernovae explosions have been observed in recent years. One of them was first observed using a robotic telescope at the California Institute of Technology's (Caltech) Palomar Observatory.

Data collected with Palomar's Samuel Oschin Telescope was transmitted from the remote mountain site in southern California to astronomers via the High-Performance Wireless Research and Education Network (HPWREN), funded by the National Science Foundation (NSF). The Nearby Supernova Factory research group at the Lawrence Berkeley Laboratory reported the co-discovery of the supernova, known as SN2005gj.

Researchers in Canada have analyzed this, along with two other supernovae, and believe that they each may be the signature of the explosive conversion of a neutron star into a quark star.

These three supernovae, each 100 times brighter than a typical supernova, have been difficult to explain. The Canadian research team thinks the explosions herald the creation of a previously unobserved and new class of objects, designated as quark stars.

A quark star is a hypothetical type of star composed of ultra dense quark matter. Quarks are the fundamental components of protons and neutrons, which make up the nucleus of atoms. The most dense objects known to exist today are neutron stars--stars composed entirely of tightly packed neutrons. A typical neutron star is some 16 miles across, yet has a mass one and a half times the mass of our Sun.

Neutron stars are formed when a massive star undergoes a supernova explosion at the end of its life. The question is, is a neutron star indeed the most dense object that exists? It is thought that if the neutrons are too tightly packed--if what scientists consider a neutron star is too dense--the resulting instability may lead to a further collapse, resulting in a second explosion and the creation of a quark star. The energy that powers that second explosion comes from neutrons breaking down into their component parts: quarks.

Further observations should help to confirm or defeat the hypothesis of quark stars, but in either case, the use of a high-speed network like HPWREN helps astronomers across the world explore the frontiers of science.

For the first time the researchers have discovered that a strong X-ray pulse is emitting from a giant black hole in a galaxy 500 million light years from Earth.

The pulse has been created by gas being sucked by gravity on to the black hole at the centre of the REJ1034+396 galaxy.

X-ray pulses are common among smaller black holes, but the Durham research is the first to identify this activity in a super-massive black hole. Most galaxies, including the Milky Way, are believed to contain super-massive black holes at their centres.

The researchers, who publish their findings in the scientific journal Nature September 18, say their discovery will increase the understanding of how gas behaves before falling on to a black hole as it feeds and develops.

Astronomers have been studying black holes for decades and are able to "see" them due to the fact that gas gets extremely hot and emits X-rays before it is swallowed completely and is lost forever.

Using Europe's powerful X-ray satellite, XMM-Newton, they found that X-rays are being emitted as a regular signal from the super-massive black hole. The frequency of the pulse is related to the size of the black hole.

Dr Marek Gierlinski, in the Department of Physics, at Durham University, said: "Such signals are a well known feature of smaller black holes in our Galaxy when gas is pulled from a companion star.

"The really interesting thing is that we have now established a link between these light-weight black holes and those millions of times as heavy as our Sun.

"Scientists have been looking for such behaviour for the past 20 years and our discovery helps us begin to understand more about the activity around such black holes as they grow."

Durham's scientists hope future research will tell them why some super-massive black holes show this behaviour while others do not.

The research was funded by the Science and Technology Facilities Council, the European Space Agency and Polish Ministry of Science and Higher Education.

The implications could be revolutionary, suggesting that gravity may not be a fundamental force of nature.

Prof. Braunstein says: "Our results didn't need the details of a black hole's curved space geometry. That lends support to recent proposals that space, time and even gravity itself may be emergent properties within a deeper theory. Our work subtly changes those proposals, by identifying quantum information theory as the likely candidate for the source of an emergent theory of gravity."

But quantum mechanics is the theory of light and atoms, and many physicists are skeptical that it could be used to explain the slow evaporation of black holes without incorporating the effects of gravity.

The research, which appears in the latest issue of Physical Review Letters, uses the basic tenets of quantum mechanics to give a new description of information leaking from a black hole.

Prof. Braunstein says: "Our results actually extend the predictions made by well-established techniques that rely on a detailed knowledge of space time and black hole geometry."

Dr. Patra adds: "We cannot claim to have proven that escape from a black hole is truly possible, but that is the most straight-forward interpretation of our results. Indeed, our results suggest that quantum information theory will play a key role in a future theory combining quantum mechanics and gravity."

"This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question," says lead author Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in Greenbelt, Md.

The tiny black hole resides in a Milky Way Galaxy binary system known as XTE J1650-500, named for its sky coordinates in the southern constellation Ara. NASA's Rossi X-ray Timing Explorer (RXTE) satellite discovered the system in 2001. Astronomers realized soon after J1650's discovery that it harbors a normal star and a relatively lightweight black hole. But the black hole’s mass had never been measured to high precision.

Shaposhnikov and his Goddard colleague Lev Titarchuk presented their results on Monday, March 31, at the American Astronomical Society High-Energy Astrophysics Division meeting in Los Angeles, Calif. Titarchuk also works at George Mason University in Fairfax, Va., and the US Naval Research Laboratory in Washington, DC.

The method used by Shaposhnikov and Titarchuk has been described in several papers in the Astrophysical Journal. It uses a relationship between black holes and the inner part of their surrounding disks, where gas spirals inward before making the fatal plunge. When the feeding frenzy reaches a moderate rate, hot gas piles up near the black hole and radiates a torrent of X-rays. The X-ray intensity varies in a pattern that repeats itself over a nearly regular interval. This signal is called a quasi-periodic oscillation, or QPO.

Astronomers have long suspected that a QPO's frequency depends on the black hole's mass. In 1998, Titarchuk realized that the congestion zone lies close in for small black holes, so the QPO clock ticks quickly. As black holes increase in mass, the congestion zone is pushed farther out, so the QPO clock ticks slower and slower. To measure the black hole masses, Shaposhnikov and Titarchuk use archival data from RXTE, which has made exquisitely precise measurements of QPO frequencies in at least 15 black holes.

Last year, Shaposhnikov and Titarchuk applied their QPO method to three black holes whose masses had been measured by other techniques. In their new paper, they extend their result to seven other black holes, three of which have well-determined masses. "In every case, our measurement agrees with the other methods," says Titarchuk. "We know our technique works because it has passed every test with flying colors."

When Shaposhnikov and Titarchuk applied their method to XTE J1650-500, they calculated a mass of 3.8 Suns, with a margin of uncertainty of only half a Sun. This value is well below the previous black hole record holder with a reliable mass measurement, GRO 1655-40, which tips the scales at about 6.3 Suns.

Below some unknown critical threshold, a dying star should produce a neutron star instead of a black hole. Astronomers think the boundary between black holes and neutron stars lies somewhere between 1.7 and 2.7 solar masses. Knowing this dividing line is important for fundamental physics, because it will tell scientists about the behavior of matter when it is scrunched into conditions of extraordinarily high density.

Despite the diminutive size of this new record holder, future space travelers had better beware. Smaller black holes like the one in J1650 exert stronger tidal forces than the much larger black holes found in the centers of galaxies, which make the little guys more dangerous to approach. "If you ventured too close to J1650's black hole, its gravity would tidally stretch your body into a strand of spaghetti," says Shaposhnikov.

Shaposhnikov adds that RXTE is the only instrument that can make the high-precision timing observations necessary for this line of research. "RXTE is absolutely crucial for these black hole mass measurements," he says.

Astronomers estimate that, on average, about one or two supernovae explode each century in our galaxy. But for Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away. All of the nearby stars capable of going supernova are much farther than this.

Any planet with life on it near a star that goes supernova would indeed experience problems. X- and gamma-ray radiation from the supernova could damage the ozone layer, which protects us from harmful ultraviolet light in the sun's rays. The less ozone there is, the more UV light reaches the surface. At some wavelengths, just a 10 percent increase in ground-level UV can be lethal to some organisms, including phytoplankton near the ocean surface. Because these organisms form the basis of oxygen production on Earth and the marine food chain, any significant disruption to them could cascade into a planet-wide problem.

Another explosive event, called a gamma-ray burst (GRB), is often associated with supernovae. When a massive star collapses on itself -- or, less frequently, when two compact neutron stars collide -- the result is the birth of a black hole. As matter falls toward a nascent black hole, some of it becomes accelerated into a particle jet so powerful that it can drill its way completely through the star before the star's outermost layers even have begun to collapse. If one of the jets happens to be directed toward Earth, orbiting satellites detect a burst of highly energetic gamma rays somewhere in the sky. These bursts occur almost daily and are so powerful that they can be seen across billions of light-years.

A gamma-ray burst could affect Earth in much the same way as a supernova -- and at much greater distance -- but only if its jet is directly pointed our way. Astronomers estimate that a gamma-ray burst could affect Earth from up to 10,000 light-years away with each separated by about 15 million years, on average. So far, the closest burst on record, known as GRB 031203, was 1.3 billion light-years away.

As with impacts, our planet likely has already experienced such events over its long history, but there's no reason to expect a gamma-ray burst in our galaxy to occur in the near future, much less in December 2012.

Named IGR J17091-3624 after the astronomical coordinates of its sky position, the binary system combines a normal star with a black hole that may weigh less than three times the sun's mass. That is near the theoretical mass boundary where black holes become possible.

Gas from the normal star streams toward the black hole and forms a disk around it. Friction within the disk heats the gas to millions of degrees, which is hot enough to emit X-rays. Cyclical variations in the intensity of the X-rays observed reflect processes taking place within the gas disk. Scientists think that the most rapid changes occur near the black hole's event horizon, the point beyond which nothing, not even light, can escape.

Astronomers first became aware of the binary system during an outburst in 2003. Archival data from various space missions show it becomes active every few years. Its most recent outburst started in February and is ongoing. The system is located in the direction of the constellation Scorpius, but its distance is not well established. It could be as close as 16,000 light-years or more than 65,000 light-years away.

The record-holder for wide-ranging X-ray variability is another black hole binary system named GRS 1915+105. This system is unique in displaying more than a dozen highly structured patterns, typically lasting between seconds and hours.

"We think that most of these patterns represent cycles of accumulation and ejection in an unstable disk, and we now see seven of them in IGR J17091," said Tomaso Belloni at Brera Observatory in Merate, Italy. "Identifying these signatures in a second black hole system is very exciting."

In GRS 1915, strong magnetic fields near the black hole's event horizon eject some of the gas into dual, oppositely directed jets that blast outward at about 98 percent the speed of light. The peak of its heartbeat emission corresponds to the emergence of the jet.

Changes in the X-ray spectrum observed by RXTE during each beat reveal that the innermost region of the disk emits enough radiation to push back the gas, creating a strong outward wind that stops the inward flow, briefly starving the black hole and shutting down the jet. This corresponds to the faintest emission. Eventually, the inner disk gets so bright and hot it essentially disintegrates and plunges toward the black hole, re-establishing the jet and beginning the cycle anew. This entire process happens in as little as 40 seconds.

While there is no direct evidence IGR J17091 possesses a particle jet, its heartbeat signature suggests that similar processes are at work. Researchers say that this system's heartbeat emission can be 20 times fainter than GRS 1915 and can cycle some eight times faster, in as little as five seconds.

Astronomers estimate that GRS 1915 is about 14 times the sun's mass, placing it among the most-massive-known black holes that have formed because of the collapse of a single star. The research team analyzed six months of RXTE observations to compare the two systems, concluding that IGR J17091 must possess a minuscule black hole.

"Just as the heart rate of a mouse is faster than an elephant's, the heartbeat signals from these black holes scale according to their masses," said Diego Altamirano, an astrophysicist at the University of Amsterdam in The Netherlands and lead author of a paper describing the findings in the Nov. 4 issue of The Astrophysical Journal Letters.

The researchers say this analysis is just the start of a larger program to compare both of these black holes in detail using data from RXTE, NASA's Swift satellite and the European XMM-Newton observatory.

"Until this study, GRS 1915 was essentially a one-off, and there's only so much we can understand from a single example," said Tod Strohmayer, the project scientist for RXTE at NASA's Goddard Space Flight Center in Greenbelt, Md. "Now, with a second system exhibiting similar types of variability, we really can begin to test how well we understand what happens at the brink of a black hole."

Launched in late 1995, RXTE is second only to Hubble as the longest serving of NASA's operating astrophysics missions. RXTE provides a unique observing window into the extreme environments of neutron stars and black holes.

Many, if not all, galaxies have massive black holes at their centers. But this supermassive black hole is the only one close enough for astronomers to study in detail, so the violent encounter is a unique chance to observe what until now has only been theorized: how a black hole gulps gas, dust and stars as it grows ever bigger.

"When we look at the black holes in the centers of other galaxies, we see them get bright and then fade, but we never know what is actually happening," said Eliot Quataert, a theoretical astrophysicist and University of California, Berkeley professor of astronomy. "This is an unprecedented opportunity to obtain unique observations and insight into the processes that go on as gas falls into a black hole, heats up and emits light. It's a neat window onto a black hole that's actually capturing gas as it spirals in."

"The next two years will be very interesting and should provide us with extremely valuable information on the behavior of matter around such massive objects, and its ultimate fate," said Reinhard Genzel, professor of physics at both UC Berkeley and the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany.

The discovery by Genzel; Stefan Gillessen of the MPE; Quataert and colleagues from Germany, Chile and Illinois will be reported online on Dec. 14, in advance of the Jan. 5 publication of the news in the British journal Nature.

Since 2008. Genzel, Gillessen, Quataert and their team have seen the gas cloud about three times the mass of Earth speeding up as it has fallen deeper into the gravitational whirlpool of the black hole. Its edges are already beginning to fray.

"It is not going to survive the experience," said first author Gillessen. He built the infrared detector on the European Southern Observatory's Very Large Telescope in Chile used to observe the movement of stars and gas in the center of the Milky Way, 27,000 light years from Earth.

By 2013, scientists should see outbursts of X-rays and radio waves as the cloud -- composed mostly hydrogen and helium gas gets hotter and is torn asunder. The light emitted around the black hole could increase by a hundredfold to a thousandfold, Quataert calculated.

The Chandra X-ray satellite has already scheduled its largest single chunk of observation time in 2012 near the Milky Way's central black hole.

Astronomers have long observed clouds of gas streaming toward the center of our Milky Way Galaxy, presumably destined to fall into the 4.3 million solar-mass black hole lurking there. But this black hole "has a surprisingly low amount of matter falling inward at the moment," Quataert said.

Since MPE astronomers began observing the black hole in 1992, they have seen only two stars as close as this gas cloud to the black hole. The crucial difference is that those stars "passed unharmed through their closest approach, (while) the gas cloud will be completely ripped apart by the tidal forces around the black hole," Gillessen said.

This particular cold cloud (about 550 Kelvin or 280 degrees Celsius) may have formed when gas pushed by stellar winds from two nearby stars collided, and is glowing under the strong ultraviolet radiation from surrounding hot stars. As the cloud skirts the gravitational influence of the black hole, it will come within about 40 billion kilometers ‑ 250 times the distance between Earth and the sun ‑ of the event horizon, the limit beyond which nothing, not even light, can escape.

Even at that distance, the gas will get stretched out, with probably half spiraling into the black hole and the rest flung outward.

As the cloud falls towards the black hole -- its current velocity is about 2,350 kilometers per second, twice what it was seven years ago -- it will interact with the hot gas present in the accretion flow around the black hole and become disrupted by turbulent interaction.

Thanks to the Very Large Telescope's years of observations of the black hole at many different wavelengths, the scientists were able simulate the time evolution of the cloud and predict that the temperature of the gas cloud should increase rapidly to several million Kelvin near the black hole, dramatically increasing X-ray emissions.

Violent video game playing has long been known to increase aggression. This study, conducted by Brad Bushman of The Ohio State University and Bryan Gibson of Central Michigan University, shows that at least for men, ruminating about the game can increase the potency of the game's tendency to lead to aggression long after the game has been turned off.

The researchers randomly assigned college students to play one of six different video games for 20 minutes. Half the games were violent (e.g., Mortal Kombat) and half were not (e.g., Guitar Hero). To test if ruminating about the game would extend the games' effect, half of the players were told over "the next 24 hours, think about your play of the game, and try to identify ways your game play could improve when you play again."

Bushman and Gibson had the participants return the next day to test their aggressiveness. For men who didn't think about the game, the violent video game players tested no more aggressive than men who had played non-violent games. But the violent video game playing men who thought about the game in the interim were more aggressive than the other groups. The researchers also found that women who played the violent video games and thought about the games did not experience increased aggression 24 hours later.

This study is the first laboratory experiment to show that violent video games can stimulate aggression for an extended period of time. The authors noted that it is "reasonable to assume that our lab results will generalize to the 'real world.' Violent gamers usually play longer than 20 minutes, and probably ruminate about their game play in a habitual manner."

You know the feeling. Call it a senior moment, absent-mindedness or a sign of what a busy active brain you have. We’ve all asked ourselves that irritating question: “Where on earth did I leave my car keys?”

Now a team of Japanese scientists claim to have come up with the answer. And the secretive artificial intelligence project codenamed Smart Goggle does not stop at elusive keys. With Yasuo Kuniyoshi’s invention balanced on your nose, nothing – be it the remote control, mobile phone or iPod – should ever go missing again.

Simply tell the glasses what you are looking for and it will play into your eye a video of the last few seconds you saw that item..

With its razor- sharp teeth, the fish known as the giant snakehead terrorises the warm waters of south-east Asia.

Which is why an angler was particularly startled to hook a 2ft specimen from a river in Lincolnshire.

Andrew Alder caught the snakehead using a sprat for bait while fishing for pike in the River Witham near North Hykeham.

He took photographs of his catch and handed them over to experts who confirmed it was the deadly predator.

So devastating is the damage a giant snakehead can wreak on other fish, frogs and their natural habitat that it is on a list of species which cannot be imported into the UK.

Mr Alder, from Lincoln, said his catch had a mouth full of razor-sharp teeth and looked absolutely terrifying.

It is thought that the fish was smuggled in for a private aquarium and then illegally released into the wild when it became too much of a nuisance.

The presence of even one of the species in British waters is a nightmare for environmentalists and conservationists.

Giant snakeheads caused chaos to indigenous fish and the environment when they were found living in rivers and lakes in the U.S. in 2002.

Snipers with high-powered rifles even set up watch to shoot the fish as they crawled ashore and entire lakes were poisoned to get rid of them.

A spokesman for the Environment Agency said: "The giant snakehead is not native to the UK and the coolness of our waters mean they are unlikely to survive for any length of time in this country.

"However, they could still pose a danger to habitat and other fish and we would like to remind people that the dumping of fish in waters is illegal in this country and should not be carried out under any circumstances.

"Not only that, but dumping of non-native fish can cause severe damage to indigenous species and their natural environment."

Ben Weir, of the Anglers Mail, said: "In all my time of working within fishing I have never heard so many concerned voices."

Luckily Mr Alder realised the potential damage the snakehead could cause and did not throw it back. It later died and he disposed of it.

Built as a tribute to 5,000 years of jewellery-making in India, the vehicle will be used as showpiece for the country's largest multinational company, Tata...

When European settlers arrived in North America, they brought their diseases with them. Shortly thereafter, large numbers of Native Americans began dying from smallpox infection. Five-hundred-year-old documents record this tale, but now scientists say they’ve found additional evidence buried deep inside human cells.

In a new study, Brendan O’Fallon and Lars Fehren-Schmitz report evidence found in genes that the Native American population dropped by half after the arrival of Europeans. O’Fallon studies genes at ARUP Laboratories in Salt Lake City. Fehren-Schmitz is an anthropologist, a scientist who studies humankind, at the University of Göttingen in Germany.

Cells make up every part of the body. Deep inside almost every cell is a long, coiled molecule called DNA. Genes are chunks of DNA that play important roles in determining one’s life. Genes help determine a person’s appearance, such as skin color and height, and also play a role in many things you can’t see, like the chance of getting a disease.

Genes change over time, and by tracking these changes scientists can learn about a person’s ancestors. O’Fallon and Fehren-Schmitz looked at genes in the mitochondria of cells. (Mitochondria are like factories that help cells use energy from food.) The scientists compared DNA from the remains of ancient Native Americans with DNA from living people descended from Native Americans.

The scientists studied patterns in the genes from the two groups and identified ways the patterns changed over time. Using statistics, which includes useful mathematical tools for analyzing large amounts of data, the researchers were able to estimate the size of the Native American population before and after the Europeans’ arrival. The comparison showed the number of native people plummeted after the colonists’ landed in the New World.

Earlier genetic studies didn’t turn up evidence of the Native American die-off. Scientists involved with the new study say that there’s now more data from ancient remains, so researchers can get a better idea of what happened.

Some scientists question the findings. “These new results confirm what’s known from historic sources, but the quality of ancient DNA data raises potential concerns,” Phillip Endicott told Science News. Endicott is a scientist at the Musée de l’Homme in Paris who looks for clues to history in DNA changes. He points out that the DNA from ancient Native Americans may have been damaged, from contamination in the ground or from scientists handling the remains.

POWER WORDS (from the New Oxford American Dictionary)

DNA, or deoxyribonucleic acid. A long molecule in nearly all living organisms that carries genetic information. Each molecule of DNA consists of two strands coiled around each other to form a double helix, a structure like a twisted ladder.

mitochondria An organelle found in large numbers in most cells. Where energy production occurs.

cell The smallest structural and functional unit of an organism, typically microscopic.

gene The basic unit of hereditary information.

The 2008 Nobel Prize in Chemistry went to the discoverers of the ‘green fluorescent protein’, known as GFP.

This remarkable protein was first observed in a species of jellyfish in 1962, and in the years since has become one of the most important biochemical tools. by attaching GFP to other proteins of interest, such as nerve cells and cancer cells, those proteins can be followed in their actions allowing scientists to map the activities of biological functions. And while that type of research may be fairly obscure for regular people to understand and follow, the GFP protein and some engineered brother proteins have been put to a commercial use most of us can relate to…

If you have an aquarium and pay attention to the very latest in cool tropical fish, you’ve no doubt heard about GloFish. These originally engineered zebrafish (that now pass their glow onto their offspring naturally) come in the standard ‘electric green’, but also in ‘starfire red’ and ‘sunburst orange’! Yes, they do faintly glow in the dark, but are best shown off under a fluorescent black light.

You could see these in your dentist or doctor’s office waiting room if you don’t have any already, so impress your care-giver by talking about the GFP protein and how the discoverers finally got their Nobel Prize! It probably won’t get you a discount on that filling or check-up, but it’ll give you something besides your sore knee or the increase in your insurance premium this year to talk about.

Links:
Green Fluorescent Protein Pioneers Share 2008 Nobel Prize in Chemistry
GloFish: Experience the Glo!