Herschel looks back in time to see today's stars bursting into life.

(Click To Enlarge)

A UK-led international team of astronomers have presented the first conclusive evidence for a dramatic surge in star birth in a newly discovered population of massive galaxies in the early Universe. Their measurements confirm the idea that stars formed most rapidly about 11 billion years ago, or about three billion years after the Big Bang, and that the rate of star formation is much faster than was thought.

The scientists used the European Space Agency's Herschel Space Observatory, an infrared telescope carrying the largest mirror ever launched into space. They studied the distant objects in detail with the Spectral and Photometric Imaging Receiver (SPIRE) camera, obtaining solid evidence that the galaxies are forming stars at a tremendous rate and have large reservoirs of gas that will power the star formation for hundreds of millions of years. Their observations also confirm that these galaxies represent a crucial episode in the build up of large galaxies around us today, such as our own Milky Way.

Dr. Scott Chapman, from the Institute of Astronomy in Cambridge, has presented the new results in a paper in a special edition of the journal Monthly Notices of the Royal Astronomical Society focusing on results from Herschel.

Scott comments "These Herschel-SPIRE measurements have revealed the new population of galaxies to be hotter than expected, due to stars forming far much more rapidly than we previously believed."

The galaxies are so distant that the light we detect from them has been travelling for more than 11 billion years. This means that we see them as they were about three billion years after the Big Bang. The key to the new results is the recent discovery of a new type of extremely luminous galaxy in the early Universe. These galaxies are very faint in visible light, as the newly-formed stars are still cocooned in the clouds of gas and dust within which they were born. This cosmic dust, which has a temperature of around -240 degrees C, is much brighter at the longer, far infrared wavelengths observed by the Herschel satellite.

A related type of galaxy was first found in 1997 (but not well understood until 2003) using the "SCUBA" camera attached to the James Clerk Maxwell Telescope on Hawaii, which detects radiation emitted at even longer submillimeter wavelengths. But these distant "submillimeter galaxies" were thought to only represent half the picture of star formation in the early Universe. Since SCUBA preferentially detects colder objects, it was suggested that similar galaxies with slightly warmer temperatures could exist but have gone largely unnoticed.

Dr. Chapman and others measured their distances using the Keck optical telescope on Hawaii and the Plateau de Bure submillimeter observatory in France, but were unable to show that they were in the throes of rapid star formation.

The new galaxies have prodigious rates of star formation, far higher than anything seen in the present-day Universe. They probably developed through violent encounters between hitherto undisturbed galaxies, after the first stars and galaxy fragments had already formed. None the less, studying these new objects gives astronomers an insight into the earliest epochs of star formation after the Big Bang.

Team colleague Dr. Isaac Roseboom from the University of Sussex sums up the work. "It was amazing and surprising to see the Herschel-SPIRE observations uncover such a dramatic population of previously unseen galaxies". Professor Seb Oliver, also from Sussex, adds: "We are really blown away by the tremendous capability of Herschel to probe the distant universe. This work by Scott Chapman gives us a real handle on how the cosmos looked early in its life."

With the new discovery, the UK-led astronomers have provided a much more accurate census of some of the most extreme galaxies in the Universe at the peak of their activity. Future observations will investigate the details of the galaxies' power source and try to establish how they will develop once their intense bursts of activity come to an end.

Every Black Hole Contains Another Universe?

Like part of a cosmic Russian doll, our universe may be nested inside a black hole that is itself part of a larger universe.

In turn, all the black holes found so far in our universe—from the microscopic to the supermassive—may be doorways into alternate realities.

According to a mind-bending new theory, a black hole is actually a tunnel between universes—a type of wormhole. The matter the black hole attracts doesn't collapse into a single point, as has been predicted, but rather gushes out a "white hole" at the other end of the black one, the theory goes.

(Related: "New Proof Unknown 'Structures' Tug at Our Universe.")

In a recent paper published in the journal Physics Letters B, Indiana University physicist Nikodem Poplawski presents new mathematical models of the spiraling motion of matter falling into a black hole. His equations suggest such wormholes are viable alternatives to the "space-time singularities" that Albert Einstein predicted to be at the centers of black holes.

According to Einstein's equations for general relativity, singularities are created whenever matter in a given region gets too dense, as would happen at the ultradense heart of a black hole.

Einstein's theory suggests singularities take up no space, are infinitely dense, and are infinitely hot—a concept supported by numerous lines of indirect evidence but still so outlandish that many scientists find it hard to accept.

If Poplawski is correct, they may no longer have to.

According to the new equations, the matter black holes absorb and seemingly destroy is actually expelled and becomes the building blocks for galaxies, stars, and planets in another reality.

(Related: "Dark Energy's Demise? New Theory Doesn't Use the Force.")

Wormholes Solve Big Bang Mystery?

The notion of black holes as wormholes could explain certain mysteries in modern cosmology, Poplawski said.

For example, the big bang theory says the universe started as a singularity. But scientists have no satisfying explanation for how such a singularity might have formed in the first place.

If our universe was birthed by a white hole instead of a singularity, Poplawski said, "it would solve this problem of black hole singularities and also the big bang singularity."

Wormholes might also explain gamma ray bursts, the second most powerful explosions in the universe after the big bang.

Gamma ray bursts occur at the fringes of the known universe. They appear to be associated with supernovae, or star explosions, in faraway galaxies, but their exact sources are a mystery. (Related: "Gamma-Ray Burst Caused Mass Extinction?")

Poplawski proposes that the bursts may be discharges of matter from alternate universes. The matter, he says, might be escaping into our universe through supermassive black holes—wormholes—at the hearts of those galaxies, though it's not clear how that would be possible.

"It's kind of a crazy idea, but who knows?" he said. (Related: "Are Wormholes Tunnels for Time Travel?")

There is at least one way to test Poplawski's theory: Some of our universe's black holes rotate, and if our universe was born inside a similarly revolving black hole, then our universe should have inherited the parent object's rotation.

If future experiments reveal that our universe appears to rotate in a preferred direction, it would be indirect evidence supporting his wormhole theory, Poplawski said.

Wormholes Are "Exotic Matter" Makers?

The wormhole theory may also help explain why certain features of our universe deviate from what theory predicts, according to physicists.

Based on the standard model of physics, after the big bang the curvature of the universe should have increased over time so that now—13.7 billion years later—we should seem to be sitting on the surface of a closed, spherical universe.

But observations show the universe appears flat in all directions.

What's more, data on light from the very early universe show that everything just after the big bang was a fairly uniform temperature.

That would mean that the farthest objects we see on opposite horizons of the universe were once close enough to interact and come to equilibrium, like molecules of gas in a sealed chamber.

Again, observations don't match predictions, because the objects farthest from each other in the known universe are so far apart that the time it would take to travel between them at the speed of light exceeds the age of the universe.

To explain the discrepancies, astronomers devised the concept of inflation.

Inflation states that shortly after the universe was created, it experienced a rapid growth spurt during which space itself expanded at faster-than-light speeds. The expansion stretched the universe from a size smaller than an atom to astronomical proportions in a fraction of a second.

The universe therefore appears flat, because the sphere we're sitting on is extremely large from our viewpoint—just as the sphere of Earth seems flat to someone standing in a field.

Inflation also explains how objects so far away from each other might have once been close enough to interact.

But—assuming inflation is real—astronomers have always been at pains to explain what caused it. That's where the new wormhole theory comes in.

According to Poplawski, some theories of inflation say the event was caused by "exotic matter," a theoretical substance that differs from normal matter, in part because it is repelled rather than attracted by gravity.

Based on his equations, Poplawski thinks such exotic matter might have been created when some of the first massive stars collapsed and became wormholes.

"There may be some relationship between the exotic matter that forms wormholes and the exotic matter that triggered inflation," he said.

(Related: "Before the Big Bang: Light Shed on 'Previous Universe.'")

Wormhole Equations an "Actual Solution"

The new model isn't the first to propose that other universes exist inside black holes. Damien Easson, a theoretical physicist at Arizona State University, has made the speculation in previous studies.

"What is new here is an actual wormhole solution in general relativity that acts as the passage from the exterior black hole to the new interior universe," said Easson, who was not involved in the new study.

"In our paper, we just speculated that such a solution could exist, but Poplawski has found an actual solution," said Easson, referring to Poplawski's equations.

(Related: "Universe 20 Million Years Older Than Thought.")

Nevertheless, the idea is still very speculative, Easson said in an email.

"Is the idea possible? Yes. Is the scenario likely? I have no idea. But it is certainly an interesting possibility."

Future work in quantum gravity—the study of gravity at the subatomic level—could refine the equations and potentially support or disprove Poplawski's theory, Easson said.

Wormhole Theory No Breakthrough

Overall, the wormhole theory is interesting, but not a breakthrough in explaining the origins of our universe, said Andreas Albrecht, a physicist at the University of California, Davis, who was also not involved in the new study.

By saying our universe was created by a gush of matter from a parent universe, the theory simply shifts the original creation event into an alternate reality.

In other words, it doesn't explain how the parent universe came to be or why it has the properties it has—properties our universe presumably inherited.

"There're really some pressing problems we're trying to solve, and it's not clear that any of this is offering a way forward with that," he said.

Still, Albrecht doesn't find the idea of universe-bridging wormholes any stranger than the idea of black hole singularities, and he cautions against dismissing the new theory just because it sounds a little out there.

"Everything people ask in this business is pretty weird," he said. "You can't say the less weird [idea] is going to win, because that's not the way it's been, by any means."

Hubble Peers Deeply into the Eagle Nebula

Hubble Peers Deeply into the Eagle Nebula

The Hubble Space Telescope has once more turned its attention towards the magnificent Eagle Nebula (Messier 16). This picture shows the northwestern part of the region, well away from the centre, and features some very bright young stars that formed from the same cloud of material. These energetic toddlers are part of an open cluster and emit ultraviolet radiation that causes the surrounding nebula to glow.

The star cluster is very bright and was discovered in the mid-eighteenth century. The nebula, however, is much more elusive and it took almost a further two decades for it to be first noted by Charles Messier in 1764. Although it is commonly known as the Eagle Nebula, its official designation is Messier 16 and the cluster is also named NGC 6611. One spectacular area of the nebula (outside the field of view) has been nicknamed “The Pillars of Creation” ever since the Hubble Space Telescope captured an iconic image of dramatic pillars of star-forming gas and dust.

The cluster and nebula are fascinating targets for small and medium-sized telescopes, particularly from a dark site free from light pollution. Messier 16 can be found within the constellation of Serpens Cauda (the Tail of the Serpent), which is sandwiched between Aquila, Sagittarius, and Ophiuchus in the heart of one of the brightest parts of the Milky Way. Small telescopes with low power are useful for observing large, but faint, swathes of the nebula, whereas 30 cm telescopes and larger may reveal the dark pillars under good conditions. But a space telescope in orbit around the Earth, like Hubble — which boasts a 2.4-metre diameter mirror and state-of-the-art instruments — is required for an image as spectacular as this one.

This picture was created from images taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys. Images through a near-infrared filter (F775W) are coloured red and images through a blue filter (F475W) are blue. The exposures times were one hour and 54 minutes respectively and the field of view is about 3.3 arcminutes across.

Spitzer Reveals a Buried Explosion Sparked by a Galactic Train Wreck

Spitzer Reveals a Buried Explosion Sparked by a Galactic Train Wreck
By Adam Hadhazy

Astronomers using NASA's Spitzer Space Telescope have found a stunning burst of star formation that beams out as much infrared light as an entire galaxy. The collision of two spiral galaxies has triggered this explosion, which is cloaked by dust that renders its stars nearly invisible in other wavelengths of light.

The starburst newly revealed by Spitzer stands as the most luminous ever seen taking place away from the centers, or nuclei, of merging parent galaxies. It blazes ten times brighter than the nearby Universe's previous most famous "off-nuclear starburst" that gleams in another galactic smashup known as the Antennae Galaxy.

The new findings show that galaxy mergers can pack a real star-making wallop far from the respective galactic centers, where star-forming dust and gases typically pool.

"This discovery proves that merging galaxies can generate powerful starbursts outside of the centers of the parent galaxies," says Hanae Inami, first author of a paper detailing the results in the July issue of The Astronomical Journal. Inami is a graduate student at The Graduate University for Advanced Studies in Japan and the Spitzer Science Center at the California Institute of Technology. She adds: "The infrared light emission of the starburst dominates its host galaxy and rivals that of the most luminous galaxies we see that are relatively close to our home, the Milky Way."

"No matter how you slice it, this starburst is one of the most luminous objects in the local Universe," agrees Lee Armus, second author of the paper and a senior research astronomer also at the Spitzer Science Center.
A dazzling galactic dust-up

Inami, Armus and their colleagues spotted the buried starburst with Spitzer in the interacting galaxies known as II Zw 096. This galactic train wreck - located around 500 million light years away in the constellation Delphinus (the Dolphin) - will continue to unfold for a few hundred million years. Gravitational forces have already dissolved the once-pinwheel shape of one of II Zw 096's pair of merging galaxies.

The ultra-bright starburst region spans 700 light-years or so - just a tiny portion of II Zw 096, which streams across some 50,000 to 60,000 light-years - yet it blasts out 80 percent of the infrared light from this galactic tumult. Based on Spitzer data, researchers estimate the starburst is cranking out stars at the breakneck pace of around 100 solar masses, or masses of our Sun, per year.

The prodigious energy output of this starburst in a decentralized location as revealed in the infrared has surprised the Spitzer researchers. The new observations go to show how the notion of a cosmic object's nature can change tremendously when viewed at different wavelengths of light. In this way, the shapes and dynamics of distant, harder-to-study galactic mergers could turn out to be a good deal more complex than current observations over a narrow range of wavelengths imply.

"Most of the far-infrared emission in II Zw 096, and hence most of the power, is coming from a region that is not associated with the centers of the merging galaxies," Inami explains. "This suggests that the appearances and interactions of distant, early galaxies during epochs when mergers were much more common than today in the Universe might be more complicated than we think."
A fleeting, perhaps prophetic vista?

In galaxy mergers, individual stars rarely slam into one another because of the vast distances separating them; even in the comparatively crowded central hubs of spiral galaxies, trillions of kilometers still often yawn between the stars.

But giant, diffuse clouds of gas and dust in galaxies do crash together - passing through each other somewhat like ocean waves - and in turn spur the gravitational collapse of dense pockets of matter into new stars. These young, hot stars shine intensely in the energetic ultraviolet part of the spectrum. In the case of II Zw 096, however, a thick shroud of gas and dust still surrounds this stellar brood. The blanket of material absorbs the stars' light and re-radiates it in the lower-energy, infrared wavelengths that gleam clear through the dust to Spitzer's camera.

Astronomers were lucky to capture this transient phase in the evolution of the starburst and of the daughter galaxy that will eventually coalesce out of the collision. "Spitzer has allowed us to see the fireworks before all the gas and dust has cleared away, giving us a preview of the exciting new galaxy being built under the blanket," Inami says.

Merging galaxies such as II Zw 096 also offer a sneak peek at the fate of our Milky Way in some 4.5 billion years when it is expected to plow into its nearest large galactic neighbor, the Andromeda Galaxy. Off-nuclear starbursts such as that in II Zw 096 and the Antennae Galaxy could occur in the vicinity of our Solar System, perhaps, which is located about two-thirds of the way out from the Milky Way's glowing, bulging center.

"This kind of dramatic thing happening in II Zw 096 could happen to the Milky Way and Andromeda when they meet in the far future," says Inami.

Galaxy on edge

Spiral galaxies are among the most magnificent objects in space. Grand and sprawling, they are icons of the night sky.

Like a snapshot of coins tossed in the air, we see them at all angles, from face-on disks to nearly edge-on lines. And sometimes we catch them so precisely to the side that what we see is hard to believe is real. But then we get pictures like this one from Hubble of the galaxy NGC 4452:

Holy perpendicularity!

There are lots of edge-on galaxies in the sky, like NGC 253 and NGC 4710, but this one is extraordinary. The alignment is perfect, and the disk is incredibly thin. Our Milky Way is 100,000 light years across and 2500 or so light years thick (a ratio of 40:1), but NGC 4452 looks even thinner than that; measuring off the picture I get a width-to-thickness ratio of 100:1.

Other things are obvious, too, and honestly a bit weird. For one thing, the central bulge of the galaxy is very small; in most edge-on galaxies it pokes above and below the disk like in NGC 4565, shown here. In that picture you can also see lots of dark dust; that’s actually complex organic molecules that are very efficient at absorbing visible light. They’re created when stars are born and when they die, and dust clouds tend to huddle close to the center of the disk.

[Note added later: It occurs to me there might be dust in the galaxy despite what I say in the next paragraph. That's because dust doesn't show up in the infrared very well, and one of the filters used was IR (as I note in a following paragraph). Also, the kind of camera used isn't as sensitive in the blue as it is in the IR, so that might also suppress seeing any dust that might be there. So take the next paragraph with -- haha -- a grain of salt.]

But NGC 4452 appears denuded of dust! I’ve never seen a galaxy quite so clean. I think it would actually pass the white glove test. As it happens, this galaxy is part of a nearby cluster called the Virgo Cluster, a collection of hundreds of galaxies about 60 million light years away. In between the galaxies is a thin fog of gas, and as the galaxies orbit each other they plow through this gas. The high speeds at which they travel can actually strip them of their own gas and dust, like when you open your car window while driving to get rid of, um, say, an obnoxious smell. Perhaps this is what happened to NGC 4452.

The disk is surrounded by a fuzzy glow, which would be the collected light from billions of stars above and below the disk. Note that if you look to the extreme edges of the disk, the fuzzy glow appears to subtly bend down on the left and up on the right. The galaxy is warped! This is common in disk galaxies (the Milky Way and nearby Andromeda galaxies are warped, and you can also see it in NGC 5866). It’s usually caused by a gravitational torque, an off-center tug, from a nearby galaxy. Since NGC 4522 is in a cluster, it’s not too surprising there might be some galaxy that could do this.

And finally, one more thing. Look at all the distant background galaxies in the picture! There are dozens of them scattered about, most much, much farther away. Mind you, this picture of NGC 4452 is a short exposure; just a combination of 12.5 minutes using a blue filter and 20 using an infrared one. This means the sky is filled with galaxies!

And each one is an island Universe, made of billions of stars along with massive gas and dust clouds, and each as spectacular and amazing as this one seen up close.

Engineers Assessing Cassini Spacecraft

Engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are working to understand what caused NASA's Cassini spacecraft to put itself into "safe mode," a precautionary standby mode. Cassini entered safe mode around 4 p.m. PDT (7 p.m. EDT) on Tuesday, Nov. 2.

Since going into safe mode, the spacecraft has performed as expected, suspending the flow of science data and sending back only data about engineering and spacecraft health. Cassini is programmed to put itself into safe mode automatically any time it detects a condition on the spacecraft that requires action from mission controllers on the ground.

Engineers say it is not likely that Cassini will be able to resume full operations before a planned Nov. 11 flyby of Saturn's moon Titan. But Cassini has 53 more Titan flybys planned in its extended mission, which lasts until 2017.

"The spacecraft responded exactly as it should have, and I fully expect that we will get Cassini back up and running with no problems," said Bob Mitchell, Cassini program manager based at JPL. "Over the more than six years we have been at Saturn, this is only the second safing event. So considering the complexity of demands we have made on Cassini, the spacecraft has performed exceptionally well for us."

Since Cassini launched in 1997, Cassini has put itself into safe mode a total of six times.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington.

Spiral Galaxies Stripped Bare

Six spectacular spiral galaxies are seen in a clear new light in images from ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile. The pictures were taken in infrared light, using the impressive power of the HAWK-I camera, and will help astronomers understand how the remarkable spiral patterns in galaxies form and evolve.

HAWK-I [1] is one of the newest and most powerful cameras on ESO’s Very Large Telescope (VLT). It is sensitive to infrared light, which means that much of the obscuring dust in the galaxies’ spiral arms becomes transparent to its detectors. Compared to the earlier, and still much-used, VLT infrared camera ISAAC, HAWK-I has sixteen times as many pixels to cover a much larger area of sky in one shot and, by using newer technology than ISAAC, it has a greater sensitivity to faint infrared radiation [2]. Because HAWK-I can study galaxies stripped bare of the confusing effects of dust and glowing gas it is ideal for studying the vast numbers of stars that make up spiral arms.

The six galaxies are part of a study of spiral structure led by Preben Grosbøl at ESO. These data were acquired to help understand the complex and subtle ways in which the stars in these systems form into such perfect spiral patterns.

The first image shows NGC 5247, a spiral galaxy dominated by two huge arms, located 60–70 million light-years away. The galaxy lies face-on towards Earth, thus providing an excellent view of its pinwheel structure. It lies in the zodiacal constellation of Virgo (the Maiden).

The galaxy in the second image is Messier 100, also known as NGC 4321, which was discovered in the 18th century. It is a fine example of a “grand design” spiral galaxy — a class of galaxies with very prominent and well-defined spiral arms. About 55 million light-years from Earth, Messier 100 is part of the Virgo Cluster of galaxies and lies in the constellation of Coma Berenices (Berenice’s Hair, named after the ancient Egyptian queen Berenice II).

The third image is of NGC 1300, a spiral galaxy with arms extending from the ends of a spectacularly prominent central bar. It is considered a prototypical example of barred spiral galaxies and lies at a distance of about 65 million light-years, in the constellation of Eridanus (the River).

The spiral galaxy in the fourth image, NGC 4030, lies about 75 million light-years from Earth, in the constellation of Virgo. In 2007 Takao Doi, a Japanese astronaut who doubles as an amateur astronomer, spotted a supernova — a stellar explosion that is briefly almost as bright as its host galaxy — going off in this galaxy.

The fifth image, NGC 2997, is a spiral galaxy roughly 30 million light-years away in the constellation of Antlia (the Air Pump). NGC 2997 is the brightest member of a group of galaxies of the same name in the Local Supercluster of galaxies. Our own Local Group, of which the Milky Way is a member, is itself also part of the Local Supercluster.

Last but not least, NGC 1232 is a beautiful galaxy some 65 million light-years away in the constellation of Eridanus (the River). The galaxy is classified as an intermediate spiral galaxy — somewhere between a barred and an unbarred spiral galaxy. An image of this galaxy and its small companion galaxy NGC 1232A in visible light was one of the first produced by the VLT (eso9845). HAWK-I has now returned to NGC 1232 to show a different view of it at near-infrared wavelengths.

As this galactic gallery makes clear, HAWK-I lets us see the spiral structures in these six bright galaxies in exquisite detail and with a clarity that is only made possible by observing in the infrared.

Giant Star Goes Supernova -- And Is Smothered By Its Own Dust

A giant star in a faraway galaxy recently ended its life with a dust-shrouded whimper instead of the more typical bang.

Ohio State University researchers suspect that this odd event -- the first one of its kind ever viewed by astronomers – was more common early in the universe.

It also hints at what we would see if the brightest star system in our galaxy became a supernova.

In a paper published online in the Astrophysical Journal, Christopher Kochanek, a professor of astronomy at Ohio State, and his colleagues describe how the supernova appeared in late August 2007, as part of the Spitzer Space Telescope Deep Wide Field Survey.

The astronomers were searching the survey data for active galactic nuclei (AGN), super-massive black holes at the centers of galaxies. AGN radiate enormous amounts of heat as material is sucked into the black hole. In particular, the astronomers were searching for hot spots that varied in temperature, since these could provide evidence of changes in how the material was falling into the black hole.

Because of the alignment of the galaxy with Earth and our sun, astronomers were not able to see what the event looked like to the naked eye while it was happening. But Kochanek believes that we might see the star brighten a decade or so from now. That’s how long it will take for the shockwave from the exploding star to reach the inner dust shell and slam it into the outer shell. Then we’ll have something to see here on Earth.

Normally, astronomers wouldn’t expect to find a supernova this way, explained then-Ohio State postdoctoral researcher Szymon Kozlowski. Supernovae release most of their energy as light, not heat.

But one very hot spot, which appeared in a galaxy some 3 billion light years from Earth, didn’t match the typical heat signal of an AGN. The visible spectrum of light emanating from the galaxy didn’t show the presence of an AGN, either – the researchers confirmed that fact using the 10-meter Keck Telescope in Hawaii.

Enormous heat flared from the object for a little over six months, then faded away in early March 2008 – another clue that the object was a supernova.

“Over six months, it released more energy that our sun could produce in its entire lifetime,” Kozlowski said.

The astronomers knew that if the source were a supernova, the extreme amount of energy it emitted would qualify it as a big one, or a “hypernova.” The temperature of the object was around 1,000 Kelvin (about 700 degrees Celsius) -- only a little hotter than the surface of the planet Venus. They wondered -- what could absorb that much light energy and dissipate it as heat?

The answer: dust, and a lot of it.

Using what they learned from the Spitzer survey, the astronomers worked backward to determine what kind of star could have spawned the supernova, and how the dust was able to partly muffle the explosion. They calculated that the star was probably a giant, at least 50 times more massive than our sun. Such massive stars typically belch clouds of dust as they near the end of their existence.

This particular star must have had at least two such ejections, they determined – one about 300 years before the supernova, and one only about four years before it. The dust and gas from both ejections remained around the star, each in a slowly expanding shell. The inner shell – the one from four years ago – would be very close to the star, while the outer shell from 300 years ago would be much farther away.

“We think the outer shell must be nearly opaque, so it absorbed any light energy that made it through the inner shell and converted it to heat,” said Kochanek, who is also the Ohio Eminent Scholar in Observational Cosmology.

That’s why the supernova showed up on the Spitzer survey as a hot dust cloud.

Krzysztof Stanek, professor of astronomy at Ohio State, said that stars probably choked on their own dust much more often in the distant past.

“These events are much more likely to happen in a small, low metallicity galaxy,” he said -- meaning a young galaxy that hadn’t been around long enough for its stars to fuse hydrogen and helium into the more complex chemicals that astronomers refer to as “metals.”

Still, Kozlowski added that more such supernovae will likely be found by NASA’s Wide-field Infrared Explorer (WISE), which was launched in December 2009. “I would expect WISE to see 100 of these events in two years, now that we know what to look for,” he said.

Because of the alignment of the galaxy with Earth and our sun, astronomers were not able to see what the event looked like to the naked eye while it was happening. But Kochanek believes that we might see the star brighten a decade or so from now. That’s how long it will take for the shockwave from the exploding star to reach the inner dust shell and slam it into the outer shell. Then we’ll have something to see here on Earth.

We do have at least one chance to see a similar light show closer to home, though.

“If Eta Carinae went supernova right now, this is what it would probably look like,” Kochanek said, referring to the brightest star system in our Milky Way Galaxy.

The two stars that make up Eta Carinae are 7,500 light years away, and they host a distinctive dust shell dubbed the Homunculus Nebula, among other layers of dust. Astronomers believe that the nebula was created when the larger of the two stars underwent a massive eruption around 1840, and that future eruptions are likely.

Growing Galaxies Gently

New observations from ESO’s Very Large Telescope have, for the first time, provided direct evidence that young galaxies can grow by sucking in the cool gas around them and using it as fuel for the formation of many new stars. In the first few billion years after the Big Bang the mass of a typical galaxy increased dramatically and understanding why this happened is one of the hottest problems in modern astrophysics. The results appear in the 14 October issue of the journal Nature.

The first galaxies formed well before the Universe was one billion years old and were much smaller than the giant systems — including the Milky Way — that we see today. So somehow the average galaxy size has increased as the Universe has evolved. Galaxies often collide and then merge to form larger systems and this process is certainly an important growth mechanism. However, an additional, gentler way has been proposed.

A European team of astronomers has used ESO’s Very Large Telescope to test this very different idea — that young galaxies can also grow by sucking in cool streams of the hydrogen and helium gas that filled the early Universe and forming new stars from this primitive material. Just as a commercial company can expand either by merging with other companies, or by hiring more staff, young galaxies could perhaps also grow in two different ways — by merging with other galaxies or by accreting material.

The team leader, Giovanni Cresci (Osservatorio Astrofisico di Arcetri) says: “The new results from the VLT are the first direct evidence that the accretion of pristine gas really happened and was enough to fuel vigorous star formation and the growth of massive galaxies in the young Universe.” The discovery will have a major impact on our understanding of the evolution of the Universe from the Big Bang to the present day. Theories of galaxy formation and evolution may have to be re-written.

The group began by selecting three very distant galaxies to see if they could find evidence of the flow of pristine gas from the surrounding space and the associated formation of new stars. They were very careful to make sure that their specimen galaxies had not been disturbed by interactions with other galaxies. The selected galaxies were very regular, smoothly rotating discs, similar to the Milky Way, and they were seen about two billion years after the Big Bang (at a redshift of around three).

In galaxies in the modern Universe the heavy elements [1] are more abundant close to the centre. But when Cresci’s team mapped their selected distant galaxies with the SINFONI spectrograph on the VLT [2] they were excited to see that in all three cases there was a patch of the galaxy, close to the centre, with fewer heavy elements, but hosting vigorously forming stars, suggesting that the material to fuel the star formation was coming from the surrounding pristine gas that is low in heavy elements. This was the smoking gun that provided the best evidence yet of young galaxies accreting primitive gas and using it to form new generations of stars.

As Cresci concludes: “This study has only been possible because of the outstanding performance of the SINFONI instrument on the VLT. It has opened a new window for studying the chemical properties of very distant galaxies. SINFONI provides information not only in two spatial dimensions, but also in a third, spectral dimension, which allows us to see the internal motions inside galaxies and study the chemical composition of the interstellar gas.”
Notes

[1] The gas filling the early Universe was almost all hydrogen and helium. The first generations of stars processed this primitive material to create heavier elements such as oxygen, nitrogen and carbon by nuclear fusion. When this material was subsequently spewed back into space by intense particle winds from massive young stars and supernova explosions the amounts of heavy elements in the galaxy gradually increased. Astronomers refer to elements other than hydrogen and helium as “heavy elements”.

[2] By carefully splitting up the faint light coming from a galaxy into its component colours using powerful telescopes and spectrographs, astronomers can identify the fingerprints of different chemicals in remote galaxies, and measure the amounts of heavy elements present. With the SINFONI instrument on the VLT astronomers can go one better and get a separate spectrum for each part of an object. This allows them to make a map that shows the quantity of heavy elements present in different parts of a galaxy and also determine where in the galaxy star formation is occurring most vigorously.

G327.1-1.1: Pushing the Envelope

G327.1-1.1 is the aftermath of a massive star that exploded as a supernova in the Milky Way galaxy. A highly magnetic, rapidly spinning neutron star called a pulsar was left behind after the explosion and is producing a wind of relativistic particles, seen in X-rays by Chandra and XMM-Newton (blue) as well as in the radio data (red and yellow). This structure is called a pulsar wind nebula. The likely location of the spinning neutron star is shown in the labeled version. The large red circle shows radio emission from the blast wave, and the composite image also contains infrared data from the 2MASS survey (red, green, and blue) that show the stars in the field.

No clear explanation is yet known for the unusual nature of G327.1-1.1, including the off-center position of the pulsar wind nebula seen in the radio data and the comet-like shape of the X-ray emission. One possibility is that we are seeing the effects of a shock wave bouncing backwards off of the shell of material swept up by the blast wave produced by the explosion, the so-called "reverse shock" from the blast wave. The pulsar is moving upwards, away from the center of the explosion, but the pulsar wind nebula is being swept towards the bottom-left of the image by the reverse shock wave that is also traveling towards the bottom-left. The direction of the pulsar's motion and of the reverse shock are shown in the labeled version.

The X-ray observations allow scientists to estimate the energy released during the supernova explosion and the age of the remnant, as well as the amount of material being swept up as the blast wave from the explosion expands. The faint bubble that the pulsar appears to be creating may also be revealing the fresh pulsar wind being blown into the region cleared out by the reverse shock.

A paper describing these results appeared in The Astrophysical Journal in February 2009 with Tea Temim of the Harvard-Smithsonian Center for Astrophysics (CfA), Patrick Slane (CfA), Bryan Gaensler (University of Sydney), Jack Hughes (Rutgers) and Eric Van Der Swaluw (Royal Netherlands Meterological Institute) as authors.

A distant sparkling eruption of diamonds

You really want to click that to get the very beefy 4000 x 4000 pixel (11 Mb) version. It’ll knock your socks off!

This Hubble image shows NGC 6934, an ancient ball of stars located about 50,000 light years away. Globular clusters are made of stars that are bound to each other gravitationally and orbiting the center on a myriad different paths — think of it as a beehive except with a hundred thousand bees each a million kilometers across. There are about 150 of these guys orbiting the Milky Way, each a dozen or so light years across and containing upwards of a million stars. NGC 6934 is pretty typical of its class, but its great distance dims it to near-obscurity. If it were as close as M 13 or Omega Centauri — both roughly half as far as NGC 6934 — it would be heralded as a gem of the night sky.

Globulars are old. We think they form all at once, with all the stars being born at the same time. Massive stars, which are blue, don’t live long before exploding as supernovae (leaving behind black holes or dense neutrons stars), so they’re all long gone in these billions-of-years-old objects. In fact, in many globulars even stars like the Sun are gone, having used up their fuel and faded away. All that’s left are low mass stars, which means all that remains are red stars.

So why are there so many blue stars in this picture? Ah, it’s false color! It was taken through two filters, one in the red, and the other in the infrared. In the picture, the red filter image is colored blue, and the infrared one is colored red. Note that the brightest stars in the picture are red (meaning they’re bright in the infrared); this is because these are red giants, stars that are nearing the ends of their lives. They’ve swollen up and cooled off, glowing brilliantly.

Even though they’re not actually blue, the ones that look blue in the image are most likely the "normal" stars that are left in the cluster, that is, stars still fusing hydrogen into helium like the Sun is, and are not yet red giants.

Globular clusters like NGC 6934 are incredibly important to our understanding of our galaxy. Because all their stars formed at once and all from the same cloud of gas, they’re a laboratory experiment in astronomy! We don’t have to correct for age or composition of stars (or at least not very much) allowing us to examine other characteristics. They’re located all over the sky, so they’re always around for viewing, and many are isolated in space, making them easy to examine. Much of what we’ve learned about how stars age and die was gleaned from globulars like NGC 6934.

Globular clusters tell us secrets of the Universe, and all we have to do is pay attention. And when they’re as stunningly beautiful as this one, that’s really easy to do.

Breaking Waves in the Stellar Lagoon

A spectacular new NASA/ESA Hubble Space Telescope image reveals the heart of the Lagoon Nebula. Seen as a massive cloud of glowing dust and gas, bombarded by the energetic radiation of new stars, this placid name hides a dramatic reality.

The Advanced Camera for Surveys (ACS) on the NASA/ESA Hubble Space Telescope has captured a dramatic view of gas and dust sculpted by intense radiation from hot young stars deep in the heart of the Lagoon Nebula (Messier 8). This spectacular object is named after the wide, lagoon-shaped dust lane that crosses the glowing gas of the nebula.

This structure is prominent in wide-field images, but cannot be seen in this close-up. However the strange billowing shapes and sandy texture visible in this image make the Lagoon Nebula’s watery name eerily appropriate from this viewpoint too.

Located four to five thousand light-years away, in the constellation of Sagittarius (the Archer), Messier 8 is a huge region of star birth that stretches across one hundred light-years. Clouds of hydrogen gas are slowly collapsing to form new stars, whose bright ultraviolet rays then light up the surrounding gas in a distinctive shade of red.

The wispy tendrils and beach-like features of the nebula are not caused by the ebb and flow of tides, but rather by ultraviolet radiation’s ability to erode and disperse the gas and dust into the distinctive shapes that we see.

In recent years astronomers probing the secrets of the Lagoon Nebula have found the first unambiguous proof that star formation by accretion of matter from the gas cloud is ongoing in this region.

Young stars that are still surrounded by an accretion disc occasionally shoot out long tendrils of matter from their poles. Several examples of these jets, known as Herbig-Haro objects, have been found in this nebula in the last five years, providing strong support for astronomers’ theories about star formation in such hydrogen-rich regions.

The Lagoon Nebula is faintly visible to the naked eye on dark nights as a small patch of grey in the heart of the Milky Way. Without a telescope, the nebula looks underwhelming because human eyes are unable to distinguish clearly between colours at low light levels.

Charles Messier, the 18th century French astronomer, observed the nebula and included it in his famous astronomical catalogue, from which the nebula’s alternative name comes. But his relatively small refracting telescope would only have hinted at the dramatic structures and colours now visible thanks to Hubble.

Cosmic Ice Sculptures: Dust Pillars in the Carina Nebula

Click on picture for Zoom View.

Enjoying a frozen treat on a hot summer day can leave a sticky mess as it melts in the Sun and deforms. In the cold vacuum of space, there is no edible ice cream, but there is radiation from massive stars that is carving away at cold molecular clouds, creating bizarre, fantasy-like structures. These one-light-year-tall pillars of cold hydrogen and dust, imaged by the Hubble Space Telescope, are located in the Carina Nebula.

This image is a composite of Hubble observations taken of the Carina Nebula region in 2005 in hydrogen light (light emitted by hydrogen atoms) along with observations taken in oxygen light (light emitted by oxygen atoms) in 2010, both times with Hubble's Advanced Camera for Surveys. The immense Carina Nebula is an estimated 7,500 light-years away in the southern constellation Carina.

A Ghostly Cosmic Pinwheel

After looking at 20 years' worth of fabulous pictures from the Hubble Space Telescope, you might get the feeling that each new release is a variation on a theme you've seen before: a supernova remnant, interacting galaxies, new stars cocooned in their placental nebulas, and so on.

But this is something different!

The dim spiral in this image is almost spooky in its perfect symmetry. The view was captured several years ago by HST's Advanced Camera for Surveys, but a few days ago it came to light (ouch! pun alert!) on a European website devoted to Hubble's discoveries.

"So what is it?" you ask.

First, I can tell you that it's real (not an artifact), it's about 3,000 light-years away in Pegasus, and it's not associated with the bright foreground star to its right.

Second, the feature itself is designated IRAS 23166+1655, which signifies that it was spotted by the Infrared Astronomical Satellite in 1983.

"So what is it?"

It's not a spiral galaxy but rather what astronomers call a pre-planetary nebula, created when an aging, swollen star starts to shed its outer layers into space — the beginning of its death throes. In this case the shedder is an extreme carbon star, one fortified with so much carbon that there's a sooty deposit in its photosphere thick enough to block the visible light trying escape from underneath. Astronomers only know a star is there because it's still hot and thus glowing brightly in the infrared.

"But why the spiral shape?"

This isn't just any old spiral; it's a perfect fit to an Archimedean spiral, something like a jet of water coming from a spinning lawn sprinkler.

The source of this pinwheel turns out to be part of a binary system, as revealed by near-infrared images taken with the Keck II telescope. As it spews matter into space, the dying star is also slowly twirling around an unseen companion.

Observers estimate that the ejected jet is moving outward at roughly 30,000 miles (50,000 km) per hour. Knowing that, and the angular spacing between successive rings (about 4½ arcseconds), observers conclude that they're spaced about 800 years apart. That is, if you took up a stationary position near the star, one of the outward-moving spiral's arms would sweep past you every 800 years.

As it turns out, the orbital period of the binary is also about 800 years. Consistent results!

Interestingly, the pinwheel is glowing faintly, but not from the stars hidden inside it. When Mark Morris (University of California, Los Angeles) and others took stock of this remarkable image in 2006, they concluded that the illumination source isn't the 12th-magnitude foreground star at the right — more likely we're seeing this ghostly pinwheel thanks to the combined glow of stars in the galactic plane.

If you want to explore the science behind this cosmic curiosity, here is the analysis by Morris's team, and here is a link to some work by Nicolas Mauron (CNRS, France) and Patrick Huggins (New York University).

Or you can skip the science and just be a little patient. "We have a much deeper HST observation with the new Wide Field Camera 3 now scheduled for this object in early October," Morris mentioned in an email, "so we're very excited about that."

Pulverized Planet Dust Might Lie Around Double Stars

Cambridge, MA - Tight double-star systems might not be the best places for life to spring up, according to a new study using data from NASA's Spitzer Space Telescope. The infrared observatory spotted a surprisingly large amount of dust around three mature, close-orbiting star pairs. Where did the dust come from? Astronomers say it might be the aftermath of tremendous planetary collisions.

"This is real-life science fiction," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "Our data tell us that planets in these systems might not be so lucky -- collisions could be common. It's theoretically possible that habitable planets could exist around these types of stars, so if there happened to be any life there, it could be doomed."

Drake is the principal investigator of the research, published in the Aug. 19 issue of the Astrophysical Journal Letters.

The particular class of binary, or double, stars in the study are about as snug as stars get. Named RS Canum Venaticorums, or RS CVns for short, they are separated by only about two million miles (3.2 million kilometers), or one-fiftieth the distance between Earth and our sun. The stellar pairs orbit around each other every few days, with one face on each star perpetually locked and pointed toward the other.

The close-knit stars are similar to the sun in size and are probably about a billion to a few billion years old. But these stars spin much faster, and, as a result, have powerful magnetic fields and giant, dark spots. The magnetic activity drives strong stellar winds -- gale-force versions of the solar wind -- that slow the stars down, pulling the twirling duos closer over time. And this is where the planetary chaos might begin.

As the stars cozy up to each other, their gravitational influences change, and this could cause disturbances to planetary bodies orbiting around both stars. Comets and any planets that might exist in the systems would start jostling about and banging into each other, sometimes in powerful collisions. This includes planets that could theoretically be circling in the double stars' habitable zone -- a region where temperatures would allow liquid water to exist. Though no habitable planets have been discovered around any stars beyond our sun at this point in time, tight double-star systems are known to host planets; for example, one system not in the study, called HW Vir, has two gas-giant planets.

"These kinds of systems paint a picture of the late stages in the lives of planetary systems," said Marc Kuchner, a co-author from NASA Goddard Space Flight Center in Greenbelt, Md. "And it's a future that's messy and violent."

Spitzer spotted the infrared glow of hot dusty disks, about the temperature of molten lava, around three such tight binary systems. One of the systems was originally flagged as having a suspicious excess of infrared light in 1983 by the Infrared Astronomical Satellite. In addition, researchers using Spitzer recently found a warm disk of debris around another star that turned out to be a tight binary system.

The team says that dust normally would have dissipated and blown away from the stars by this mature stage in their lives. They conclude that something -- most likely planetary collisions -- must therefore be kicking up the fresh dust. In addition, because dusty disks now have been found around four, older binary systems, the scientists know that the observations are not a fluke. Something chaotic is very likely going on.

If any life forms did exist in these star systems, and they could look up at the sky, they would have quite a view. Marco Matranga, first author of the paper, from the Harvard-Smithsonian Center for Astrophysics and now a visiting astronomer at the Palermo Astronomical Observatory in Sicily, said, "The skies there would have two huge suns, like the ones above the planet Tatooine in 'Star Wars.'"

Other authors include V.L. Kashyap of the Harvard-Smithsonian Center for Astrophysics; and Massimo Marengo of Iowa State University, Ames.

The Spitzer observations were made before it ran out of its liquid coolant in May 2009, officially beginning its warm mission.

Alien Solar System Looks Strikingly Like Ours

Astronomers have discovered a group of at least five planets – with hints of two more – circling around a star in an arrangement similar to our own solar system. Confirmation of the extra planets would make this the highest tally of alien worlds ever spotted around a single star.

The planets and their own sun-like star are about 127 light-years from Earth, astronomers with the European Southern Observatory said. It is one of just 15 planetary systems known to have more than three worlds.

The five planets circle their parent star, HD 10180, in a regular pattern like the planets of our solar system, only in a more compact arrangement, the researchers said.

Of the two potential additional planets that may be present, one may have a mass that is the closest to the Earth's yet seen, if it is confirmed, they added. [The Strangest Alien Planets]

"We have found what is most likely the system with the most planets yet discovered," astronomer Christophe Lovis, lead author of the study, said in a statement Tuesday. "This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets.

"Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system."

The research was announced at an international colloquium on extrasolar planets at the Observatoire de Haute-Provence, France. It came just days ahead of a scheduled announcement from NASA's Kepler planet-hunting mission to discuss an "intriguing planetary system."

Lovis and his team used the planet-hunting HARPS spectrograph instrument on a 3.6-meter telescope at the European Southern Observatory in La Silla, Chile, to detect the system in the constellation Hydrus.

The instrument allows astronomers to measure the movement, or "wobble," of a star caused by the gravitational pull of planets orbiting around it.

The five strongest wobble signals were caused by planets with masses similar to Neptune, between 13 and 25 times the mass of the Earth.

Though these planets are relatively large, they are located close to their parent star and race around at intervals that range from just six days to 600 days.

The closest planet is not quite 5.6 million miles (9 million km) from HD 10180, compared to the 93 million miles (150 million km) separating Earth from the sun, a distance also known as an astronomical unit. The distance of the farthest one from its star is about 1.4 AU.

When compared to our solar system, all of these planets would fit inside the orbit of Mars and appear to have nearly circular orbits.

The wobble method for detecting alien planets also suggested more worlds are orbiting HD 10180, one of them up close and the other far off.

"We also have good reasons to believe that two other planets are present," Lovis said.

One of these extra planets, if confirmed, would be much like Saturn, with at least 65 times the mass of Earth and year that lasts 2,200 days.

The other potential planet is the most tantalizing for astronomers. If confirmed, it would be the least massive world ever found outside our solar system, with a mass just 1.4 times that of Earth. It is thought to orbit extremely close to the star – just 2 percent of an AU – and completes its circuit in only 1.18 Earth days, researchers said.

"This object causes a wobble of its star of only about 3 km/hour— slower than walking speed — and this motion is very hard to measure," said study team member Damien Segransan.

This planet would probably be a small, rocky world similar to the hellish planet Corot-7b, which orbits close to a different star. There the daytime temperatures can reach 4,000 degrees Fahrenheit (2,200 degrees Celsius), with nighttime lows of minus 350 F (minus 210 C).

The newly found system could set the extrasolar record for most known planets. It currently shares the record with the system around the star 55 Cancri, which has five planets, two of them gas giants.

No gas giants seem to be present in the HD 10180 star system.

"Systems of low-mass planets like the one around HD 10180 appear to be quite common, but their formation history remains a puzzle," Lovis said.

Galactic Plane - Aquila

This image combines data from PACS and SPIRE to form a three-colour image. PACS images at 70 microns (blue), 160microns (green) are combined with the SPIRE 250 microns channel (red). Cooler material is shown in red, while warmer material is blue - but all just 10-50 degreen above absolute zero. This image is taken in constellation of Aquila and shows the entire assembly line of newborn stars. The diffuse glow reveals the widespread cold reservoir of raw material which our Galaxy has in stock for the production of new stars.

Two bright star forming regions are seen on the left and centre, called W43 and G29.9 respectively. Below W43, a cavity can be seen in the interstellar medium. The strong winds from the stars forming in the dense clump are pushing the material out, blowing the bobble.
This image is taken as part of a project called "Hi-GAL", which aims to image a strip across the plane of our Galaxy towards its central regions. This is a section 30 degrees away from the centre of our Galaxy.

Ambitious Survey Spots Stellar Nurseries

Astronomers scanning the skies as part of ESO’s VISTA Magellanic Cloud survey have now obtained a spectacular picture of the Tarantula Nebula in our neighbouring galaxy, the Large Magellanic Cloud. This panoramic near-infrared view captures the nebula itself in great detail as well as the rich surrounding area of sky. The image was obtained at the start of a very ambitious survey of our neighbouring galaxies, the Magellanic Clouds, and their environment.

The leader of the survey team, Maria-Rosa Cioni (University of Hertfordshire, UK) explains: "This view is of one of the most important regions of star formation in the local Universe — the spectacular 30 Doradus star-forming region, also called the Tarantula Nebula. At its core is a large cluster of stars called RMC 136, in which some of the most massive stars known are located."

ESO’s VISTA telescope [1] is a new survey telescope at the Paranal Observatory in Chile (eso0949). VISTA is equipped with a huge camera that detects light in the near-infrared part of the spectrum, revealing a wealth of detail about astronomical objects that gives us insight into the inner workings of astronomical phenomena. Near-infrared light has a longer wavelength than visible light and so we cannot see it directly for ourselves, but it can pass through much of the dust that would normally obscure our view. This makes it particularly useful for studying objects such as young stars that are still enshrouded in the gas and dust clouds from which they formed. Another powerful aspect of VISTA is the large area of the sky that its camera can capture in each shot.

This image is the latest view from the VISTA Magellanic Cloud Survey (VMC). The project will scan a vast area — 184 square degrees of the sky (corresponding to almost one thousand times the apparent area of the full Moon) including our neighbouring galaxies the Large and Small Magellanic Clouds. The end result will be a detailed study of the star formation history and three-dimensional geometry of the Magellanic system.

Chris Evans from the VMC team adds: “The VISTA images will allow us to extend our studies beyond the inner regions of the Tarantula into the multitude of smaller stellar nurseries nearby, which also harbour a rich population of young and massive stars. Armed with the new, exquisite infrared images, we will be able to probe the cocoons in which massive stars are still forming today, while also looking at their interaction with older stars in the wider region.”

The wide-field image shows a host of different objects. The bright area above the centre is the Tarantula Nebula itself, with the RMC 136 cluster of massive stars in its core. To the left is the NGC 2100 star cluster. To the right is the tiny remnant of the supernova SN1987A (eso1032). Below the centre are a series of star-forming regions including NGC 2080 — nicknamed the “Ghost Head Nebula” — and the NGC 2083 star cluster.

The VISTA Magellanic Cloud Survey is one of six huge near-infrared surveys of the southern sky that will take up most of the first five years of operations of VISTA.
Notes

[1] VISTA ― the Visible and Infrared Survey Telescope for Astronomy ― is the newest telescope at ESO’s Paranal Observatory in northern Chile. VISTA is a survey telescope working at near-infrared wavelengths and is the world’s largest survey telescope. Its large mirror, wide field of view and very sensitive detectors will reveal a completely new view of the southern sky.

The telescope is housed on the peak adjacent to the one hosting ESO’s Very Large Telescope (VLT) and shares the same exceptional observing conditions. VISTA has a main mirror that is 4.1 m across. In photographic terms it can be thought of as a 67-megapixel digital camera with a 13 000 mm f/3.25 mirror lens.
More information

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

A Galactic Spectacle

A beautiful new image of two colliding galaxies has been released by NASA's Great Observatories. The Antennae galaxies, located about 62 million light-years from Earth, are shown in this composite image from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold and brown), and the Spitzer Space Telescope (red). The Antennae galaxies take their name from the long antenna-like "arms," seen in wide-angle views of the system. These features were produced by tidal forces generated in the collision.

The collision, which began more than 100 million years ago and is still occurring, has triggered the formation of millions of stars in clouds of dust and gas in the galaxies. The most massive of these young stars have already sped through their evolution in a few million years and exploded as supernovas.

The X-ray image from Chandra shows huge clouds of hot, interstellar gas that have been injected with rich deposits of elements from supernova explosions. This enriched gas, which includes elements such as oxygen, iron, magnesium, and silicon, will be incorporated into new generations of stars and planets. The bright, point-like sources in the image are produced by material falling onto black holes and neutron stars that are remnants of the massive stars. Some of these black holes may have masses that are almost one hundred times that of the Sun.

The Spitzer data show infrared light from warm dust clouds that have been heated by newborn stars, with the brightest clouds lying in the overlapping region between the two galaxies.

The Hubble data reveal old stars and star-forming regions in gold and white, while filaments of dust appear in brown. Many of the fainter objects in the optical image are clusters containing thousands of stars.

The Chandra image was taken in December 1999. The Spitzer image was taken in December 2003. The Hubble image was taken in July 2004 and February 2005.

Spitzer Space Telescope Surveys the Milky Way's Outback

A new survey by NASA's Spitzer Space Telescope has turned up treasures aplenty in the outer regions of the Milky Way, where amidst fogs of interstellar chemicals some rare, young and enormous stars are blasting gas out into space.

These very first images from the ongoing GLIMPSE360 survey are but a taste of what will be revealed during Spitzer's scan of the far-flung reaches of our galaxy.

"GLIMPSE360 will see to the edge of the Milky Way galaxy better than any telescope has before," says Barbara Whitney, principal investigator for the survey, Senior Scientist at the University of Wisconsin and a Senior Research Scientist at the Space Science Institute in Boulder, Colorado.

The new survey is an extension of the recent GLIMPSE survey that looked into the Milky Way's bustling center full of stars and dust, and home to a monstrous black hole. From our solar system, which is about two-thirds of the way out from this galactic "downtown," Spitzer's view now shifts to mostly remote areas. In this way, GLIMPSE360 is picking up where the original GLIMPSE left off and will survey the remaining half of the Milky Way's disk out to its very edge.

"It's like looking into the wilderness of our galaxy," says Whitney. "While mapping the stars and dust out there, we hope to answer some major questions about an environment that is very different from the inner Milky Way."

Astronomers want to know how stars arise in this vast expanse that has less star-forming material and a lower concentration of heavy elements, or "metallicity," than found toward the galactic core. Other goals of GLIMPSE360 are detailing the structure of the outer galaxy that is swept by two massive spiral arms and where the Milky Way's star-spangled disk thickens. While trailblazing our galaxy's outback, Spitzer will also come across many fascinating cosmic objects for researchers to further investigate.

Rather like the early westward explorers of North America, GLIMPSE 360 will forge all the way ahead to where our galaxy's shores meet the relative void of intergalactic space. Scientists do not yet know where the Milky Way galaxy "ends," and if recent discoveries in other galaxies are any indication, the outer rim may host unexpected and unknown pockets of star formation.

"We look forward to what GLIMPSE360 will show us," Whitney says. "The adventure is just getting started."

GLIMPSE360, which stands for Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, began last September and will run through early 2011. A full processing of its reams of data will then take another year or so, but chunks of this valuable astronomical information will be released along the way. When combined with the original GLIMPSE and GLIMPSE3D data, the finished survey will offer future researchers a complete field of view of our disk-like, circular galactic abode - hence "360" in the name - ranging in height from 2.7 degrees to 8.4 degrees at the Milky Way's center, or a band five to almost 17 full moons high.

GLIMPSE360 is part of Spitzer's "warm" mission that started in May 2009 when the satellite depleted its liquid coolant and now surveys the cosmos in infrared wavelengths of light 3.6 and 4.5 microns across, or millionths of a meter.

Hyperfast Star Was Booted from Milky Way

July 22, 2010: A hundred million years ago, a triple-star system was traveling through the bustling center of our Milky Way galaxy when it made a life-changing misstep. The trio wandered too close to the galaxy's giant black hole, which captured one of the stars and hurled the other two out of the Milky Way. Adding to the stellar game of musical chairs, the two outbound stars merged to form a super-hot, blue star.

This story may seem like science fiction, but astronomers using NASA's Hubble Space Telescope say it is the most likely scenario for a so-called hypervelocity star, known as HE 0437-5439, one of the fastest ever detected. It is blazing across space at a speed of 1.6 million miles (2.5 million kilometers) an hour, three times faster than our Sun's orbital velocity in the Milky Way. Hubble observations confirm that the stellar speedster hails from our galaxy's core.

Black Hole Blows Big Bubble

Combining observations made with ESO’s Very Large Telescope and NASA’s Chandra X-ray telescope, astronomers have uncovered the most powerful pair of jets ever seen from a stellar black hole. This object, also known as a microquasar, blows a huge bubble of hot gas, 1000 light-years across, twice as large and tens of times more powerful than other known microquasars. The discovery is reported this week in the journal Nature.

“We have been astonished by how much energy is injected into the gas by the black hole,” says lead author Manfred Pakull. “This black hole is just a few solar masses, but is a real miniature version of the most powerful quasars and radio galaxies, which contain black holes with masses of a few million times that of the Sun.”

Black holes are known to release a prodigious amount of energy when they swallow matter. It was thought that most of the energy came out in the form of radiation, predominantly X-rays. However, the new findings show that some black holes can release at least as much energy, and perhaps much more, in the form of collimated jets of fast moving particles. The fast jets slam into the surrounding interstellar gas, heating it and triggering an expansion. The inflating bubble contains a mixture of hot gas and ultra-fast particles at different temperatures. Observations in several energy bands (optical, radio, X-rays) help astronomers calculate the total rate at which the black hole is heating its surroundings.

The astronomers could observe the spots where the jets smash into the interstellar gas located around the black hole, and reveal that the bubble of hot gas is inflating at a speed of almost one million kilometres per hour.

“The length of the jets in NGC 7793 is amazing, compared to the size of the black hole from which they are launched,” says co-author Robert Soria [1]. “If the black hole were shrunk to the size of a soccer ball, each jet would extend from the Earth to beyond the orbit of Pluto.”

This research will help astronomers understand the similarity between small black holes formed from exploded stars and the supermassive black holes at the centres of galaxies. Very powerful jets have been seen from supermassive black holes, but are thought to be less frequent in the smaller microquasar variety. The new discovery suggests that many of them may simply have gone unnoticed so far.

The gas-blowing black hole is located 12 million light-years away, in the outskirts of the spiral galaxy NGC 7793 (eso0914b). From the size and expansion velocity of the bubble the astronomers have found that the jet activity must have been ongoing for at least 200 000 years.

Notes

Astronomers do not have yet any means of measuring the size of the black hole itself. The smallest stellar black hole discovered so far has a radius of about 15 km. An average stellar black hole of about 10 solar masses has a radius of about 30 km, while a “big” stellar black hole may have a radius of up to 300 km. This is still much smaller than the jets, which extend out to several hundreds light years on each side of the black hole, or about several thousand million million km!
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This result appears in a paper published in this week’s issue of the journal Nature (A 300 parsec long jet-inflated bubble around a powerful microquasar in the galaxy NGC 7793, by Manfred W. Pakull, Roberto Soria and Christian Motch).

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

R Coronae Australis: A Cosmic Watercolour

This magnificent view of the region around the star R Coronae Australis was created from images taken with the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile. R Coronae Australis lies at the heart of a nearby star-forming region and is surrounded by a delicate bluish reflection nebula embedded in a huge dust cloud. The image reveals surprising new details in this dramatic area of sky. Click To Enlarge

The star R Coronae Australis lies in one of the nearest and most spectacular star-forming regions. This portrait was taken by the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. The image is a combination of twelve separate pictures taken through red, green and blue filters.

This image shows a section of sky that spans roughly the width of the full Moon. This is equivalent to about four light-years at the distance of the nebula, which is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown). The complex is named after the star R Coronae Australis, which lies at the centre of the image. It is one of several stars in this region that belong to the class of very young stars that vary in brightness and are still surrounded by the clouds of gas and dust from which they formed.

The intense radiation given off by these hot young stars interacts with the gas surrounding them and is either reflected or re-emitted at a different wavelength. These complex processes, determined by the physics of the interstellar medium and the properties of the stars, are responsible for the magnificent colours of nebulae. The light blue nebulosity seen in this picture is mostly due to the reflection of starlight off small dust particles. The young stars in the R Coronae Australis complex are similar in mass to the Sun and do not emit enough ultraviolet light to ionise a substantial fraction of the surrounding hydrogen. This means that the cloud does not glow with the characteristic red colour seen in many star-forming regions.

The huge dust cloud in which the reflection nebula is embedded is here shown in impressively fine detail. The subtle colours and varied textures of the dust clouds make this image resemble an impressionist painting. A prominent dark lane crosses the image from the centre to the bottom left. Here the visible light emitted by the stars that are forming inside the cloud is completely absorbed by the dust. These objects could only be detected by observing at longer wavelengths, by using a camera that can detect infrared radiation.

R Coronae Australis itself is not visible to the unaided eye, but the tiny, tiara-shaped constellation in which it lies is easily spotted from dark sites due to its proximity on the sky to the larger constellation of Sagittarius and the rich star clouds towards the centre of our own galaxy, the Milky Way.
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ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

VISTA Views the Sculptor Galaxy

Click To Enlarge

A spectacular new image of the Sculptor Galaxy (NGC 253) has been taken with the ESO VISTA telescope at the Paranal Observatory in Chile as part of one of its first major observational campaigns. By observing in infrared light VISTA’s view is less affected by dust and reveals a myriad of cooler stars as well as a prominent bar of stars across the central region. The VISTA image provides much new information on the history and development of the galaxy.

The Sculptor Galaxy (NGC 253) lies in the constellation of the same name and is one of the brightest galaxies in the sky. It is prominent enough to be seen with good binoculars and was discovered by Caroline Herschel from England in 1783. NGC 253 is a spiral galaxy that lies about 13 million light-years away. It is the brightest member of a small collection of galaxies called the Sculptor Group, one of the closest such groupings to our own Local Group of galaxies. Part of its visual prominence comes from its status as a starburst galaxy, one in the throes of rapid star formation. NGC 253 is also very dusty, which obscures the view of many parts of the galaxy (eso0902). Seen from Earth, the galaxy is almost edge on, with the spiral arms clearly visible in the outer parts, along with a bright core at its centre.

VISTA, the Visible and Infrared Survey Telescope for Astronomy, the latest addition to ESO’s Paranal Observatory in the Chilean Atacama Desert, is the world’s largest survey telescope. After being handed over to ESO at the end of 2009 (eso0949) the telescope was used for two detailed studies of small sections of the sky before it embarked on the much larger surveys that are now in progress. One of these “mini surveys” was a detailed study of NGC 253 and its environment.

As VISTA works at infrared wavelengths it can see right through most of the dust that is such a prominent feature of the Sculptor Galaxy when viewed in visible light. Huge numbers of cooler stars that are barely detectable with visible-light telescopes are now also seen. The VISTA view reveals most of what was hidden by the thick dust clouds in the central part of the disc and allows a clear view of a prominent bar of stars across the nuclear region — a feature that is not seen in visible light pictures. The majestic spiral arms now spread over the whole disc of the galaxy.

The spectacular viewing conditions VISTA shares with ESO’s Very Large Telescope (VLT), located on the next mountain peak, also allow VISTA images to be exceptionally sharp for a ground-based telescope.

With this powerful instrument at their command astronomers wanted to peel away some of the mysteries of the Sculptor Galaxy. They are studying the myriad of cool red giant stars in the halo that surrounds the galaxy, measuring the composition of some of NGC 253’s small dwarf satellite galaxies, and searching for as yet undiscovered new objects such as globular clusters and ultra-compact dwarf galaxies that would otherwise be invisible without the deep VISTA infrared images. Using the unique VISTA data they plan to map how the galaxy formed and has evolved.

A Cauldron of Newborn Stars

N11, the Bean Nebula
A cocoon of young stars and gas clouds
informally known as N 11 (the Bean Nebula) lies 160,000 light-years
away in the Large Magellanic Cloud. This portion of it, about 6
arcminutes across, was captured with the Hubble Space Telescope’s
Advanced Camera for Surveys. Click here for a larger view.
NASA / ESA / J. M. Apellániz

A Cauldron of Newborn Stars

Some of the night sky's most spectacular nebulas involve giant clouds of hydrogen gas (termed H II regions), where massive young stars have illuminated their surroundings with intense, ultraviolet-rich light. Once ionized, the gas glows with the unmistakable crimson of hydrogen-alpha emission at a wavelength of 656 nm.

Many of these brilliant cotton-candy whorls lie not in the Milky Way proper but rather 160,000 light-years away in the Large Magellanic Cloud.

A stunning example is LHA 120-N 11, known more informally as N 11 or the Bean Nebula. It ranks as the second largest star-forming region in the LMC, behind 30 Doradus, the Tarantula Nebula. (Historical footnote: LHA 120-N 11 was first cataloged in 1956 by the late Karl Henize, an astronomer-turned-astronaut.)

Recently Jesús Maíz Apellániz (Astrophysics Institute of Andalucía, Spain) used the Hubble Space Telescope's Advanced Camera for Surveys to capture this stunning, 6-arcminute-wide portion of the much-larger nebula.

It beautifully illustrates the sequence of events that occurs in such regions. Near the bottom is a cluster massive blue-white stars, spectral types O and B, whose stellar winds and radiation have pushed away the residual gas to create a relatively clear pocket. As this ejected gas moves outward, it collides with surrounding dense clouds, causing them to collapse and start to form new stars. These newborns then light up their surroundings.

This isn't the first time astronomers have targeted N 11 with HST. A series of images taken in 1999 with the observatory's Wide Field Planetary Camera 2 were made available in 2004 as part of the Hubble Heritage series. But the new ACS views reveal much finer details.

In addition to the June 22nd release of the Apellániz composite, you'll find a nice 50-second-long animation here that zooms in on the LMC and N 11.