Stephen Hawking's New Black Hole Theory: Scientists Remain Unconvinced

Miriam Kramer, space.com Staff Writer, 01/28/14

Famed astrophysicist Stephen Hawking has shaken up the popular science world with his newest study about the basic nature of black holes, but is his idea revolutionary? Some scientists aren't convinced.

Hawking's new black hole study -- entitled "Information Preservation and Weather Forecasting for Black Holes" – was published through the preprint journal arXiv.org and has not yet undergone the peer review vetting process typical for academic papers. It attempts to solve a paradox surrounding the basic building blocks of how the universe works.

"Hawking's paper is short and does not have a lot of detail, so it is not clear what his precise picture is, or what the justification is," Joseph Polchinski of the Kavli Institute wrote in an email to SPACE.com. [The Strangest Black Holes in the Universe]

Current theories about black holes hinge upon what's known as the "firewall paradox." This paradox pits Einstein's theory of general relativity against quantum theory in the context of a black hole. The paradox, developed by Polchinski and colleagues about two years ago, is based upon a thought experiment about would happen to a person if he or she fell into a black hole.

If an astronaut fell into a black hole, according to Einstein's theory, he or she would simply float past a point known as the "event horizon" with "no drama." The event horizon refers to the point of no return at which not even light can escape from the black hole. The astronaut wouldn't realize he or she had drifted into the black hole at all. The black hole would then pull the astronaut apart before it crushed the space explorer into its dense core.

On the other side of the paradox lies quantum mechanics, the physics theory that explains the behavior of small particles. In the thought experiment, quantum theory suggests that an astronaut would not find a "no drama" area at the event horizon, but instead would encounter a "firewall" just inside the black hole that would destroy the unlucky traveler.

In 1974, Stephen Hawking found that matter and energy can escape a black hole through what is now known as Hawking radiation. However, he contended that the radiation would be so scrambled that scientists could never work backwards to understand what fell into the black hole in the first place. This violates a basic piece of quantum theory, the idea that information cannot be destroyed.

In 2004, Hawking had a change of heart and admitted he was wrong about information loss. However, no one is quite sure how information could escape a black hole. Information radiating out of a black hole is not compatible with general relativity, and destroying information isn't possible within the confines of quantum theory. So, who is right?

Hawking's two-page study attempts to resolve the issue by doing away with event horizons and replacing them with the idea of "apparent horizons."

"The absence of event horizons means that there are no black holes -- in the sense of regimes from which light can't escape to infinity," Hawking wrote. "There are, however, apparent horizons, which persist for a period of time."

These apparent horizons shift with the behavior of quantum particles within the black hole. This theory suggests, then, that information can radiate from the black hole.

However, this idea doesn't seem to address the firewall paradox at all, said Raphael Bousso, a theoretical physicist at the University of California, Berkeley.

"It's not possible to have both of those things, to have no drama at the apparent horizon and to have the information come out," Bousso told SPACE.com. "Stephen just doesn't discuss this argument, so it's unclear how he means to address it."

Don Page, physicist at the University of Alberta in Canada, agreed. "I do not think that eliminating event horizons by itself solves the firewall problem, which is a subtle problem," he wrote in an email.

And an event horizon-free black hole isn't a new proposal, either, Page said.

"The idea that a black hole does not truly have an event horizon goes back more than a third of a century, and I would not be surprised if someone could trace it back even many years earlier," Page told SPACE.com via email.

Black holes are mysterious objects that not even light can escape. But what exactly are they?

1.     M assive gravitational singularities where light cannot even escape.

2.     The mouth of a wormhole that leads to another place, or even universe.

3.     A fluke of physics.

4.     An invention by mankind to try and fathom the complex nature of an unknowable universe.

View Results

Return To Poll

A new PBS documentary about Hawking's life and work is set to air Wednesday (Jan. 29) night. Check local listings.

Read Hawking's full study, called "Information Preservation and Weather Forecasting for Black Holes," on arXiv.org: http://arxiv.org/abs/1401.5761

Follow Miriam Kramer @mirikramer and Google+. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.

EDITOR'S RECOMMENDATIONS

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·           BLACK HOLES: Warping Space and Time

Miriam interned at Popular Science, Popular Mechanics and Oak Ridge National Laboratory before coming to SPACE.com. She graduated with her degree in journalism from the University of Tennessee after working with the microbiology and anthropology departments. She received her master's in science, health and environmental reporting from New York University.

http://www.space.com/24454-stephen-hawking-black-hole-theory.html

Stephen Hawking: 'There are no black holes'

Notion of an 'event horizon', from which nothing can escape, is incompatible with quantum theory, physicist claims.

Zeeya Merali, 01/24/14

Most physicists foolhardy enough to write a paper claiming that “there are no black holes” -- at least not in the sense we usually imagine -- would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.

In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.

“There is no escape from a black hole in classical theory,” Hawking told Nature. Quantum theory, however, “enables energy and information to escape from a black hole”. A full explanation of the process, the physicist admits, would require a theory that successfully merges gravity with the other fundamental forces of nature. But that is a goal that has eluded physicists for nearly a century. “The correct treatment,” Hawking says, “remains a mystery.”

Hawking posted his paper on the arXiv preprint server on 22 January¹. He titled it, whimsically, 'Information preservation and weather forecasting for black holes', and it has yet to pass peer review. The paper was based on a talk he gave via Skype at a meeting at the Kavli Institute for Theoretical Physics in Santa Barbara, California, in August 2013 (watch video of the talk).

Fire fighting

Hawking's new work is an attempt to solve what is known as the black-hole firewall paradox, which has been vexing physicists for almost two years, after it was discovered by theoretical physicist Joseph Polchinski of the Kavli Institute and his colleagues (see 'Astrophysics: Fire in the hole!').

In a thought experiment, the researchers asked what would happen to an astronaut unlucky enough to fall into a black hole. Event horizons are mathematically simple consequences of Einstein's general theory of relativity that were first pointed out by the German astronomer Karl Schwarzschild in a letter he wrote to Einstein in late 1915, less than a month after the publication of the theory. In that picture, physicists had long assumed, the astronaut would happily pass through the event horizon, unaware of his or her impending doom, before gradually being pulled inwards -- stretched out along the way, like spaghetti -- and eventually crushed at the 'singularity', the black hole’s hypothetical infinitely dense core.

But on analysing the situation in detail, Polchinski’s team came to the startling realization that the laws of quantum mechanics, which govern particles on small scales, change the situation completely. Quantum theory, they said, dictates that the event horizon must actually be transformed into a highly energetic region, or 'firewall', that would burn the astronaut to a crisp.

This was alarming because, although the firewall obeyed quantum rules, it flouted Einstein’s general theory of relativity. According to that theory, someone in free fall should perceive the laws of physics as being identical everywhere in the Universe -- whether they are falling into a black hole or floating in empty intergalactic space. As far as Einstein is concerned, the event horizon should be an unremarkable place.

Beyond the horizon

Now Hawking proposes a third, tantalizingly simple, option. Quantum mechanics and general relativity remain intact, but black holes simply do not have an event horizon to catch fire. The key to his claim is that quantum effects around the black hole cause space-time to fluctuate too wildly for a sharp boundary surface to exist.

In place of the event horizon, Hawking invokes an “apparent horizon”, a surface along which light rays attempting to rush away from the black hole’s core will be suspended. In general relativity, for an unchanging black hole, these two horizons are identical, because light trying to escape from inside a black hole can reach only as far as the event horizon and will be held there, as though stuck on a treadmill. However, the two horizons can, in principle, be distinguished. If more matter gets swallowed by the black hole, its event horizon will swell and grow larger than the apparent horizon.

Conversely, in the 1970s, Hawking also showed that black holes can slowly shrink, spewing out 'Hawking radiation'. In that case, the event horizon would, in theory, become smaller than the apparent horizon. Hawking’s new suggestion is that the apparent horizon is the real boundary.

“The absence of event horizons means that there are no black holes -- in the sense of regimes from which light can't escape to infinity,”

Hawking writes.

“The picture Hawking gives sounds reasonable,” says Don Page, a physicist and expert on black holes at the University of Alberta in Edmonton, Canada, who collaborated with Hawking in the 1970s. “You could say that it is radical to propose there’s no event horizon. But these are highly quantum conditions, and there’s ambiguity about what space-time even is, let alone whether there is a definite region that can be marked as an event horizon.”

Although Page accepts Hawking’s proposal that a black hole could exist without an event horizon, he questions whether that alone is enough to get past the firewall paradox. The presence of even an ephemeral apparent horizon, he cautions, could well cause the same problems as does an event horizon.

Unlike the event horizon, the apparent horizon can eventually dissolve. Page notes that Hawking is opening the door to a scenario so extreme “that anything in principle can get out of a black hole”. Although Hawking does not specify in his paper exactly how an apparent horizon would disappear, Page speculates that when it has shrunk to a certain size, at which the effects of both quantum mechanics and gravity combine, it is plausible that it could vanish. At that point, whatever was once trapped within the black hole would be released (although not in good shape).

If Hawking is correct, there could even be no singularity at the core of the black hole. Instead, matter would be only temporarily held behind the apparent horizon, which would gradually move inward owing to the pull of the black hole, but would never quite crunch down to the centre. Information about this matter would not destroyed, but would be highly scrambled so that, as it is released through Hawking radiation, it would be in a vastly different form, making it almost impossible to work out what the swallowed objects once were.

“It would be worse than trying to reconstruct a book that you burned from its ashes,” says Page. In his paper, Hawking compares it to trying to forecast the weather ahead of time: in theory it is possible, but in practice it is too difficult to do with much accuracy.

Polchinski, however, is sceptical that black holes without an event horizon could exist in nature. The kind of violent fluctuations needed to erase it are too rare in the Universe, he says. “In Einstein’s gravity, the black-hole horizon is not so different from any other part of space,” says Polchinski. “We never see space-time fluctuate in our own neighbourhood: it is just too rare on large scales.”

Raphael Bousso, a theoretical physicist at the University of California, Berkeley, and a former student of Hawking's, says that this latest contribution highlights how “abhorrent” physicists find the potential existence of firewalls. However, he is also cautious about Hawking’s solution. “The idea that there are no points from which you cannot escape a black hole is in some ways an even more radical and problematic suggestion than the existence of firewalls,” he says. "But the fact that we’re still discussing such questions 40 years after Hawking’s first papers on black holes and information is testament to their enormous significance."

Nature, DOI: doi:10.1038/nature.2014.14583

References

1.     Hawking, S. W. Preprint at http://arxiv.org/abs/1401.5761 (2014).

Show context

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http://www.nature.com/news/stephen-hawking-there-are-no-black-holes-1.14583

Warped Space-Time Around Black Holes Visualized

Stephanie Pappas, LiveScience Senior Writer,

For the first time, physicists have visualized what goes on during the collision of two black holes, providing insight into what one researcher calls the "stormy behavior" of space and time during such a merger.

The findings could help researchers interpret gravitational signals from space to reconstruct the cosmic events that created them, said study researcher Kip Thorne, a theoretical physicist at the California Institute of Technology. The study also opens up a new way to understand black holes, gravity and cosmology.

"It's as though we had only seen the surface of the ocean on a calm day," Thorne told LiveScience. "We'd never seen the ocean in a storm, we'd never seen a breaking wave, we'd never seen water spouts … We have never before understood how warped space and time behave in a storm."

Here's how black holes and space-time are linked: The theory of general relativity, proposed by Albert Einstein in 1915, describes how gravity affects very massive, huge things such as black holes and the universe itself. According to this theory, gravity actually warps the fabric of space-time in such a way that massive objects bend the universe (think a Sumo wrestler on a soft mat) so that objects can't help but fall toward them. Even time can be bent by gravity, the theory goes.

Vortex and tendex

In other words, researchers had a good handle on the forces created by a quietly spinning black hole. They were also able to simulate the results of black hole collisions to see what type of gravitational waves the collisions create. "What we were not able to do is go down and look at the merger itself," Thorne said. [See a video of the black hole collisions]

To visualize a black hole merger, the researchers used two concepts, one old and one new: vortex lines and tendex lines. These lines are the equivalent of the lines drawn to represent magnetic fields, said study author Robert Owen, a postdoctoral researcher in astronomy at Cornell University.

Vortex lines represent a twisting force in space-time. If you were to fall into a vortex line, your body would be wrung like a wet dish towel, Owen said. Tendex lines, which are a new concept, represent a stretching or squeezing force. [Visualization of vortex lines]

"Tendex is actually a word that we had to invent because it didn't exist before this," Owen said.

Using supercomputers, the researchers created simulations of the vortex and tendex lines that would be created when black holes merge. The patterns differ depending on how the merger happens, Thorne said. For example, a head-on collision of two black holes ejects doughnut-shaped vortexes from the merger. Two black holes spiraling into each other create a very different arrangement.

"This is where we see vortexes sticking out of the merged black hole that swing around the merged black hole like spiral arms of the galaxy or like water spraying out of a rotating sprinkler head," Thorne said.

In another simulation of spinning black holes orbiting into each other, the vortexes diffused into one another, Thorne said.

Tracing the source

The researchers are working on three follow-up studies to explore the details of the dynamics involved, Owen said. He said the research team expects that tendexes and vortexes will be used to investigate lots of situations where gravitational forces are very strong, including just after the Big Bang that may have created the universe about 13.7 billion years ago.

Whether any valuable insights will come out of the new visualization method has yet to be seen, University of Texas, Brownsville and Southmost Texas College physicist Richard Price told LiveScience. But the method has more potential than any other method he knows of, Price said.

"My initial impression [upon hearing about the research] was, 'Yeah. This could work,'" said Price, who was not involved in the study.

"You can't calculate everything; you've got to know where to look," Price added. "And therefore, you need to have the ability to visualize."

The results may also help researchers understand the findings of the Laser Interferometer Gravitational-Wave Observatory, or LIGO, an instrument that detects gravitational waves from space. Before, researchers knew enough about black hole collisions to figure out what sorts of waves LIGO should be looking for, Thorne said. Now, scientists can start interpreting those waves when they come in.

"We want to be able to look at the shapes of the waves and be able to go back and say what was happening to produce the waves," Thorne said.

You can follow LiveScience senior writer Stephanie Pappas on Twitter @sipappas.

Twisted Physics: 7 Mind-Blowing Findings 

Images: Black Holes of the Universe 

Wacky Physics: The Coolest Little Particles in Nature 

http://news.yahoo.com/s/livescience/20110413/sc_livescience/warpedspacetimearoundblackholesvisualized

Famous Black Hole Sheds New Light on Warped Space, Magnetic Fields

Charles Q. Choi, SPACE.com Contributor

The skewed light from near the well-known black hole Cygnus X-1 is revealing new details about the warped space and extraordinarily powerful magnetic fields close to it, astronomers find.

The black hole Cygnus X-1 – the first ever to be discovered by astronomers – is about 10 times the mass of the sun, 18 miles (60 kilometers) wide and 8,000 light-years away in the constellation of Cygnus, the Swan. It sucks gas away from a closely orbiting blue supergiant star, which super-heats as it spirals inward, emitting high-energy X-rays and gamma rays.

A great deal remains mysterious about the effects that the crushing gravity and extreme magnetic fields close to black holes have on space-time, matter and energy. Now, for the first time, scientists have seen polarized light from near a black hole, revealing key details about how Cygnus X-1 behaves. [Photos: Black Holes of the Universe]

When light travels freely through space, it can vibrate in any direction. However, light can get polarized, meaning it vibrates in just one direction, under specific circumstances, such as when it scatters off surfaces or passes through matter.

Using the Ibis telescope onboard the European Space Agency's Integral satellite, researchers observed Cygnus X-1 over the course of seven years. They concentrated on light generated in the black hole's corona, a relatively tiny region around the Cygnus X-1 that is less than 800 kilometers in diameter.

Past studies had seen X-rays from plasma heated to 216 million degrees Fahrenheit (120 million degrees Celsius) in the corona, but Integral had detected light from an unknown source there as well. [Video: Black Holes: Warping Time and Space]

"Our results have shown for the first time that this unknown high energy emission is strongly polarized, which implies that it should be produced by synchrotron radiation, a signature of a strong magnetic field at work close to the event horizon of the black hole" — essentially its edge, past which there is no return, researcher Philippe Laurent, an astronomer at the French Atomic and Alternative Energies Commission's Institute of Research into the Fundamental Laws of the Universe in Paris, told SPACE.com.

"People were thinking that theoretically a magnetic field could be there, but here is the first observational evidence of it," he added.

This powerful magnetic field close to Cygnus X-1's event horizon could be focusing particles rushing into the black hole into a jet away from it. "Our results could be the first evidence that this jet is launched in the vicinity of the black hole," Laurent said.

Since it emerges so close to Cygnus X-1's event horizon, this polarized light could yield insights regarding the physics close in, as well as properties of the black hole itself, such as its spin.

"There is no reason why other black hole binaries should not produce polarized light," Laurent added. "We should observe this phenomenon in many other systems, also may be outside our galaxy."

Laurent and his colleagues detailed their findings online March 24 in the journal Science.

Follow SPACE.com contributor Charles Q. Choi on Twitter @cqchoi. Visit SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

• Black Holes of the Universe 
• Black Holes: Warping Time & Space 
• Giant Black Hole Looks Like 'Eye of Sauron,' Scientists Say 

http://news.yahoo.com/s/space/20110324/sc_space/famousblackholeshedsnewlightonwarpedspacemagneticfields

For Fully Mature Black Holes, Time Stands Still

Clara Moskowitz,, SPACE.com Senior Writer

The end of a black hole’s evolution may be a mind-bending kind of space-time independent of time. A new study proposes a method to tell how far any black hole is from reaching this end state.

Black holes are some of the weirdest things in the universe. They occur when mass is packed into a tiny volume, squished to its ultimate density.

Though observations suggest black holes are prevalent in the universe, scientists still don't really understand what goes on inside them. The equations of general relativity usually used to understand the physics of the universe break down in these cases. 

"It is really beyond the physics we know," said Juan Antonio Valiente Kroon, a mathematician at Queen Mary, University of London. "To understand what happens inside a black hole, we need to invent new physics."

Mercifully, the physics for the end state of a black hole is somewhat simpler. A solution to the equations of general relativity was found that produced a situation called "Kerr spacetime." Scientists now think Kerr spacetime is what happens when a black hole has reached its final evolutionary state.

"Mainly the equations of relativity are so complex that for relativistic systems, the only way you can probe these equations is by means of computer," Valiente Kroon told SPACE.com. "Solutions like this Kerr solution are really exceptional. The Kerr solution is one of the few explicitly known solutions to general relativity that have a direct physical meaning."

Kerr spacetime is time-independent, meaning that nothing in Kerr spacetime changes over time. In effect, time stands still. A black hole in such a state is essentially stationary.

"One could say once it has reached this stage, there are no further processes taking place," Valiente Kroon said.

In their new study, Valiente Kroon and Thomas Backdahl, his colleague at Queen Mary, have calculated a formula to determine how close a black hole is to reaching the Kerr state.

This can happen very quickly – even in seconds – depending on the object's mass.

To apply the formula, scientists would examine the region around a black hole called its event horizon. Once mass, or even light, passes within the event horizon of a black hole, it cannot escape the black hole's gravitational clutches.

The researchers think their development could aid scientists who are building computer simulations of black holes and aiming to align them with observations of actual black holes.

Astronomers think most galaxies, including our own Milky Way, host supermassive black holes in their centers. Some researchers suspect that these are actually Kerr black holes.

Valiente Kroon and Backdahl detail their work in the Jan. 19 issue of the journal Proceedings of the Royal Society A.

You can follow SPACE.com senior writer Clara Moskowitz on Twitter @ClaraMoskowitz.

• Gallery: Black Holes Of The Universe 
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 http://news.yahoo.com/s/space/20110127/sc_space/forfullymatureblackholestimestandsstill

How Much Mass Makes a Black Hole? Astronomers Challenge Current Theories

ScienceDaily (Aug. 19, 2010) — Using ESO's Very Large Telescope, European astronomers have for the first time demonstrated that a magnetar -- an unusual type of neutron star -- was formed from a star with at least 40 times as much mass as the Sun. The result presents great challenges to current theories of how stars evolve, as a star as massive as this was expected to become a black hole, not a magnetar. This now raises a fundamental question: just how massive does a star really have to be to become a black hole?

To reach their conclusions, the astronomers looked in detail at the extraordinary star cluster Westerlund 1, located 16 000 light-years away in the southern constellation of Ara (the Altar). From previous studies, the astronomers knew that Westerlund 1 was the closest super star cluster known, containing hundreds of very massive stars, some shining with a brilliance of almost one million suns and some two thousand times the diameter of the Sun (as large as the orbit of Saturn).

"If the Sun were located at the heart of this remarkable cluster, our night sky would be full of hundreds of stars as bright as the full Moon," says Ben Ritchie, lead author of the paper reporting these results.

Westerlund 1 is a fantastic stellar zoo, with a diverse and exotic population of stars. The stars in the cluster share one thing: they all have the same age, estimated at between 3.5 and 5 million years, as the cluster was formed in a single star-formation event.

A magnetar is a type of neutron star with an incredibly strong magnetic field -- a million billion times stronger than that of the Earth, which is formed when certain stars undergo supernova explosions. The Westerlund 1 cluster hosts one of the few magnetars known in the Milky Way. Thanks to its home in the cluster, the astronomers were able to make the remarkable deduction that this magnetar must have formed from a star at least 40 times as massive as the Sun.

As all the stars in Westerlund 1 have the same age, the star that exploded and left a magnetar remnant must have had a shorter life than the surviving stars in the cluster. "Because the lifespan of a star is directly linked to its mass -- the heavier a star, the shorter its life -- if we can measure the mass of any one surviving star, we know for sure that the shorter-lived star that became the magnetar must have been even more massive," says co-author and team leader Simon Clark. "This is of great significance since there is no accepted theory for how such extremely magnetic objects are formed."

The astronomers therefore studied the stars that belong to the eclipsing double system W13 in Westerlund 1 using the fact that, in such a system, masses can be directly determined from the motions of the stars.

By comparison with these stars, they found that the star that became the magnetar must have been at least 40 times the mass of the Sun. This proves for the first time that magnetars can evolve from stars so massive we would normally expect them to form black holes. The previous assumption was that stars with initial masses between about 10 and 25 solar masses would form neutron stars and those above 25 solar masses would produce black holes.

"These stars must get rid of more than nine tenths of their mass before exploding as a supernova, or they would otherwise have created a black hole instead," says co-author Ignacio Negueruela. "Such huge mass losses before the explosion present great challenges to current theories of stellar evolution."

"This therefore raises the thorny question of just how massive a star has to be to collapse to form a black hole if stars over 40 times as heavy as our Sun cannot manage this feat," concludes co-author Norbert Langer.

The formation mechanism preferred by the astronomers postulates that the star that became the magnetar -- the progenitor -- was born with a stellar companion. As both stars evolved they would begin to interact, with energy derived from their orbital motion expended in ejecting the requisite huge quantities of mass from the progenitor star. While no such companion is currently visible at the site of the magnetar, this could be because the supernova that formed the magnetar caused the binary to break apart, ejecting both stars at high velocity from the cluster.

"If this is the case it suggests that binary systems may play a key role in stellar evolution by driving mass loss -- the ultimate cosmic 'diet plan' for heavyweight stars, which shifts over 95% of their initial mass," concludes Clark.

Notes

[1] The open cluster Westerlund 1 was discovered in 1961 from Australia by Swedish astronomer Bengt Westerlund, who later moved from there to become ESO Director in Chile (1970-74). This cluster is behind a huge interstellar cloud of gas and dust, which blocks most of its visible light. The dimming factor is more than 100 000, and this is why it has taken so long to uncover the true nature of this particular cluster.

Westerlund 1 is a unique natural laboratory for the study of extreme stellar physics, helping astronomers to find out how the most massive stars in our Milky Way live and die. From their observations, the astronomers conclude that this extreme cluster most probably contains no less than 100 000 times the mass of the Sun, and all of its stars are located within a region less than 6 light-years across. Westerlund 1 thus appears to be the most massive compact young cluster yet identified in the Milky Way galaxy.

All stars so far analysed in Westerlund 1 have masses at least 30-40 times that of the Sun. Because such stars have a rather short life -- astronomically speaking -- Westerlund 1 must be very young. The astronomers determine an age somewhere between 3.5 and 5 million years. So, Westerlund 1 is clearly a "newborn" cluster in our galaxy.

More information

The research will soon appear in the research journal Astronomy and Astrophysics ("A VLT/FLAMES survey for massive binaries in Westerlund 1: II. Dynamical constraints on magnetar progenitor masses from the eclipsing binary W13," by B. Ritchie et al.). The same team published a first study of this object in 2006 ("A Neutron Star with a Massive Progenitor in Westerlund 1," by M.P. Muno et al., Astrophysical Journal, 636, L41).

The team is composed of Ben Ritchie and Simon Clark (The Open University, UK), Ignacio Negueruela (Universidad de Alicante, Spain), and Norbert Langer (Universität Bonn, Germany, and Universiteit Utrecht, the Netherlands).

The astronomers used the FLAMES instrument on ESO's Very Large Telescope at Paranal, Chile to study the stars in the Westerlund 1 cluster.

http://www.sciencedaily.com/releases/2010/08/100818085938.htm