Friday, 31 October 2014

"Moment of Awe" --The Ghostly Light from 200 Billion Outcast Stars in Pandora's Galaxy Cluster

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NASA’s Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed “Pandora’s Cluster,” also known as Abell 2744. The Hubble team estimates that the combined light of about 200 billion outcast stars contributes approximately 10 percent of the cluster’s brightness.

The scattered stars are no longer bound to any one galaxy, and drift freely between galaxies in the cluster. By observing the light from the orphaned stars, Hubble astronomers have assembled forensic evidence that suggests as many as six galaxies were torn to pieces inside the cluster over a stretch of 6 billion years.

“The Hubble data revealing the ghost light are important steps forward in understanding the evolution of galaxy clusters,” said Ignacio Trujillo of The Instituto de Astrofísica de Canarias (IAC), Santa Cruz de Tenerife, Spain. “It is also amazingly beautiful in that we found the telltale glow by utilizing Hubble’s unique capabilities.”

Computer modeling of the gravitational dynamics among galaxies in a cluster suggests that galaxies as big as our Milky Way Galaxy are the likely candidates as the source of the stars. The doomed galaxies would have been pulled apart like taffy if they plunged through the center of a galaxy cluster where gravitational tidal forces are strongest. Astronomers have long hypothesized that the light from scattered stars should be detectable after such galaxies are disassembled. However, the predicted “intracluster” glow of stars is very faint and was therefore a challenge to identify.

“The results are in good agreement with what has been predicted to happen inside massive galaxy clusters,” said Mireia Montes of the IAC, lead author of the paper published in the Oct. 1 issue of the Astrophysical Journal.

Because these extremely faint stars are brightest at near-infrared wavelengths of light, the team emphasized that this type of observation could only be accomplished with Hubble’s infrared sensitivity to extraordinarily dim light.

Hubble measurements determined that the phantom stars are rich in heavier elements like oxygen, carbon, and nitrogen. This means the scattered stars must be second or third-generation stars enriched with the elements forged in the hearts of the universe’s first-generation stars. Spiral galaxies – like the ones believed to be torn apart -- can sustain ongoing star formation that creates chemically-enriched stars.

Weighing more than 4 trillion solar masses, Abell 2744 is a target in the Frontier Fields program. This ambitious three-year effort teams Hubble and NASA’s other Great Observatories to look at select massive galaxy clusters to help astronomers probe the remote universe. Galaxy clusters are so massive that their gravity deflects light passing through them, magnifying, brightening, and distorting light in a phenomenon called gravitational lensing. Astronomers exploit this property of space to use the clusters as a zoom lens to magnify the images of far-more-distant galaxies that otherwise would be too faint to be seen.

Montes’ team used the Hubble data to probe the environment of the foreground cluster itself. There are five other Frontier Fields clusters in the program, and the team plans to look for the eerie “ghost light” in these clusters, too.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

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"Unexpected Planet" Discovered by Yale Astronomers

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A new planet, called PH3c, located 2,300 light years from Earth and has an atmosphere loaded with hydrogen and helium has been discovered by Yale astronomers and the Planet Hunters program. The elusive orb nearly avoided detection. This is because PH3c has a highly inconsistent orbit time around its sun, due to the gravitational influence of other planets in its system.

"On Earth, these effects are very small, only on the scale of one second or so," said Joseph Schmitt, a Yale graduate student and first author of the paper. "PH3c's orbital period changed by 10.5 hours in just 10 orbits."

That inconsistency kept it from being picked up by automated computer algorithms that search stellar light curves and identify regular dips caused by objects passing in front of stars.

Luckily, Planet Hunters came to the rescue. The program, which has found more than 60 planet candidates since 2010, enlists citizen scientists to check survey data from the Kepler spacecraft. Planet Hunters recently unveiled a new website and an expanded scientific mission.

"It harnesses the human dimension of science," said Debra Fischer, who leads the exoplanets group at Yale and is a co-author of the paper. "Computers can't find the unexpected, but people can, when they eyeball the data."

More than 300,000 volunteers are part of Planet Hunters, which is coordinated by Yale and the University of Oxford. The program's revamped website will allow Planet Hunters to analyze data more quickly than before, Fischer said. In addition, Planet Hunters is launching an effort to see if there is a correlation between types of stars and the planets that form around them.

"I think we'll be able to contribute some really unique science this way," Fischer said. The planet is described in the Oct. 29 online edition of The Astrophysical Journal.

Not only did Planet Hunters spot PH3c, but the discovery also enabled astronomers to better characterize two other planets — one on each side of PH3c. An outer planet, PH3d, is slightly larger and heavier than Saturn, for example. An inner planet, PH3b, may have a rocky composition, like Earth.

"Finding the middle planet was key to confirming the others and allowing us to find their masses," Schmitt said. "The outer planet's orbital period also changes slightly, by about 10 minutes. You need to see both planets' changing orbital periods in order to find out the masses of the planets. One planet doesn't give enough information."

There's also a quirky aspect of the planetary trio, Schmitt added. The outer planet's year is 1.91 times longer than the middle planet's year, and the middle planet's year is 1.91 times longer than the inner planet's year.

"We're not sure if this is just a coincidence or whether this might tell us something about how the planets were formed," Schmitt said.

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Thursday, 30 October 2014

Kepler Mission Findings Reveal Planetary Systems Vastly Different from Earths

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A team of planetary scientsts have compared their findings to data gathered from NASA’s planet-hunting Kepler Space Telescope and have concluded that the atmospheric mass of the planets Kepler found is, in some cases, far greater than the thin veneer of air covering Earth.

Co-author Christoph Mordasini, who studies planet and star formation at the Max Planck Institute for Astronomy, cautioned there is likely an observational bias with the Kepler data. “Kepler systems are so compact, with the planets closer to their star than in our solar system,” said Mordasini. “Maybe some of these objects formed early in their system’s history, in the presence of lots of gas and dust,” he said. “This would have made their atmospheres relatively massive compared to Earth. Our planet probably only formed when the gas was already gone, so it could not form a similar atmosphere.

Planetary systems come to be in a cloud of gas and dust, the theory goes. If enough mass gathers in a part of the cloud, that section collapses and creates a star surrounded by a thin disk. When the star ignites, its radiative force will gradually clear the area around it of any debris.

Over just a few million years, the hydrogen and helium in the disk surrounding the star partially spirals onto the star, while the rest gets pushed farther and farther out into space. Proto-Earth likely had a hydrogen-rich atmosphere at this stage, but over time (with processes such as vulcanism, comet impacts, and biological activity) its atmosphere gradually changed to the nitrogen and oxygen composition we see today.

Kepler’s data has showed other differences from our own solar system. In our own solar system, there is a vast size difference between Earth and the next-biggest planet, Neptune, which has a radius almost four times that of Earth’s. This means there’s a big dividing line when it comes to size between terrestrial planets and gas giants in our solar system.

In Kepler surveys (as well as surveys from other planet-hunting telescopes), scientists have found more of a gradient. There are other planetary systems out there with planets in between Earth’s and Neptune’s sizes, which are sometimes called “super-Earths” or “mini-Neptunes.” Whether planets of this size are habitable is up for debate.

“The gap between the Earth’s and Uranus’ or Neptune’s size, and also in their composition, doesn’t exist in extrasolar planets. So, what we see in the Solar System is not the rule,” Mordasini said.

The planets that Kepler has picked up, however, tend to be massive and closer to their star, and are therefore easier to detect. They pass more frequently across the face of their parent star, making them more easily spotted from Earth.

The size implies that they managed to grab their disk’s primordial hydrogen and helium atmosphere before it got blown away. Hydrogen and helium are light elements, so a star’s radiation would puff up the hydrogen and helium atmosphere far more than what we see on Earth, with its heavier elements.

What does this mean? The team predicts that in some cases, when astronomers measure the radius of a planet, that measurement also includes a bulky atmosphere. In other words, the planet underneath could be a lot smaller than what Kepler’s measurements could indicate.

This process assumes that the planet has an iron core and silica mantle, just like the Earth, but orbits its parent star about 10 times closer than we do ours. If the atmosphere is more massive — even 1 percent of the planet’s mass is many thousands of times more massive than Earth’s — it creates more pressure on the surface.

“It depends, but you can imagine this pressure is comparable to the deepest parts of the Earth’s ocean. Additionally, these atmospheres can be isolating and insulating for heat, so it’s also very hot on the surface,” Mordasini said.

High temperatures on Earth are known to destroy amino acids, the building blocks of carbon-based life. The atmosphere may be more massive, but it is also delicate. It wouldn’t take too much of a push to send hydrogen, the lightest element, away from the planet and into space.

Young stars like the Sun in its youth are especially active in x-rays and ultraviolet radiation. When these forms of light hit a planetary atmosphere, they tend to heat it up. Since heating expands gases, the atmosphere grows. An atmosphere that flows beyond certain heights can get so high that part of it gets “unbounded” from the planet’s gravity and escapes into space.

In our own solar system, for example, Mars likely lost its hydrogen to space over time while a heavier kind of hydrogen (called deuterium) remained behind. A new NASA orbiting spacecraft called Mars Atmosphere and Volatile Evolution (MAVEN) has just arrived at the Red Planet to study more about atmospheric escape today and researchers will to try to extrapolate that knowledge to space.

By contrast, the planet Venus is an example of having an exceptionally persistent atmosphere. The mostly carbon dioxide atmosphere is so thick today that the planet is completely shrouded in clouds. Underneath the atmosphere is a hellish environment, one in which the spacecraft that have made it there have only survived a few minutes in the 864 º Fahrenheit (462 º Celsius) heat on the surface. It is widely presumed that atmospheres like that of Venus would be too hot for carbon-based life.

Why Venus, Mars and Earth are so different in their atmospheric composition and history is among the questions puzzling astronomers today. Understanding atmospheric escape on each of these worlds will be helpful, scientists say.

“How strong atmospheric escape is depends on fundamental properties such as mass or planetary orbit,” Mordasini said. “We found out for giant planets like Jupiter, the operation is typically not as strong.”

Future work of the team includes considering atmospheres that are not made of hydrogen or helium, which could bring researchers a step closer to understanding how different types of elements work on planets. Eventually, this could feed into models predicting habitability.

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"Down Under" Physicists Propose a Radical Parallel Universes Theory


Australian physicists are challenging the foundations of quantum science with a new, and of course, unfalsifiable, theory based on the existence of, and interactions between, parallel universes. The team proposes that parallel universes really exist, and that they interact. That is, rather than evolving independently, nearby worlds influence one another by a subtle force of repulsion. They show that such an interaction could explain everything that is bizarre about quantum mechanics.

In a paper published in the journal Physical Review X, Howard Wiseman and Michael Hall from Griffith University's Centre for Quantum Dynamics, and Dr Dirk-Andre Deckert from the University of California, take interacting parallel worlds out of the realm of science fiction and into that of hard science. Or, so they say.

Quantum theory is needed to explain how the universe works at the microscopic scale, and is believed to apply to all matter. But it is notoriously difficult to fathom, exhibiting weird phenomena which seem to violate the laws of cause and effect.

As the American theoretical physicist Richard Feynman once noted: "I think I can safely say that nobody understands quantum mechanics." The "Many-Interacting Worlds" approach developed at Griffith University provides a new perspective on this baffling field and shows that they, too, don't understand quantum mechanics.

"The idea of parallel universes in quantum mechanics has been around since 1957," says Professor Wiseman. "In the well-known "Many-Worlds Interpretation", each universe branches into a bunch of new universes every time a quantum measurement is made. All possibilities are therefore realised. But critics question the reality of these other universes, since they do not influence our universe at all. On this score, our "Many Interacting Worlds" approach is completely different, as its name implies."

According to Wiseman and his colleages: The universe we experience is just one of a gigantic number of worlds. Some are almost identical to ours while most are very different; All of these worlds are equally real, exist continuously through time, and possess precisely defined properties; All quantum phenomena arise from a universal force of repulsion between 'nearby' (i.e. similar) worlds which tends to make them more dissimilar.

"The beauty of our approach is that if there is just one world our theory reduces to Newtonian mechanics, while if there is a gigantic number of worlds it reproduces quantum mechanics," he says. "In between it predicts something new that is neither Newton's theory nor quantum theory. We also believe that, in providing a new mental picture of quantum effects, it will be useful in planning experiments to test and exploit quantum phenomena."

We think perhaps that Weisman and Hall's theory is the result of a wee bit too many pints of Toohey’s Old at the local Griffith pub.

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Wednesday, 29 October 2014

"Hot" Quote of the Day: The Search for Advanced Intelligent Life


Looking for radio signals (at least those used for communication) makes about as much sense as looking for evidence of telegraph poles on other planets. Considering many star systems out there may be millions (billions?) of years older than our own planet, certainly any advanced civilization would have long ago moved past using modulated radio frequency as a form of communication.

So at best SETI seems to be a big distraction, something the establishment can point to as proof that they are taking the issue of intelligent alien life seriously while actually ignoring what is obvious to the majority of people on this planet – we are not alone and perhaps never have been. Another “Blue Book” white wash.

Is someone afraid of us finding out something?'

Steve, October 28, 2014

Image at the top of the page shows hte SETI Institute’s Allen Telescope Array (ATA), which hunts for radio signals from intelligent alien life.

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"A Cosmic Wheel Within a Wheel" --Binary Star Planet Lifeline Discovered


"Almost half the Sun-like stars were born in binary systems," says Emmanuel Di Folco with the Observatoire de Paris. "This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation."

Like a wheel in a wheel, the complex star system, GG Tau-A, contains a large, outer disc encircling the entire system as well as an inner disc around the main central star. This second inner disc has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.

While observing these structures with ALMA Observatory in Chile, the team made the exciting discovery of gas clumps in the region between the two discs. The new observations suggest that material is being transferred from the outer to the inner disc, creating a sustaining lifeline between the two.

"Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the discs, allowing one to feed off the other," explains Dutrey. "These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation."

Planets are born from the material left over from star birth. This is a slow process, meaning that an enduring disc is a prerequisite for planet formation. If the feeding process into the inner disc now seen with ALMA occurs in other multiple-star systems the findings introduce a vast number of new potential locations to find exoplanets in the future.

The first phase of exoplanet searches was directed at single-host stars like the Sun. More recently it has been shown that a large fraction of giant planets orbit binary-star systems. Now, researchers have begun to take an even closer look and investigate the possibility of planets orbiting the individual stars of multiple-star systems. The new discovery supports the possible existence of such planets, giving exoplanet discoverers new happy hunting grounds.

The Daily Galaxy ESO

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"A Vast Place of Stellar Life" --An Infrared Probe of Ringed Galaxy NGC 1291

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This ringed galaxy is actually a vast place of stellar life. Though galaxy NGC 1291 shown in this newly released image from NASA's Spitzer Space Telescope is quite old, roughly 12 billion years, it is marked by an unusual ring where newborn stars are igniting. "The rest of the galaxy is done maturing," said Kartik Sheth of the National Radio Astronomy Observatory of Charlottesville, Virginia. "But the outer ring is just now starting to light up with stars."

NGC 1291 is located about 33 million light-years away in the constellation Eridanus. It is what's known as a barred galaxy, because its central region is dominated by a long bar of stars (in the new image, the bar is within the blue circle and looks like the letter "S").

The bar formed early in the history of the galaxy. It churns material around, forcing stars and gas from their original circular orbits into large, non-circular, radial orbits. This creates resonances -- areas where gas is compressed and triggered to form new stars. Our own Milky Way galaxy has a bar, though not as prominent as the one in NGC 1291.

Sheth and his colleagues are busy trying to better understand how bars of stars like these shape the destinies of galaxies. In a program called Spitzer Survey of Stellar Structure in Galaxies, or S4G, Sheth and his team of scientists are analyzing the structures of more than 3,000 galaxies in our local neighborhood. The farthest galaxy of the bunch lies about 120 million light-years away -- practically a stone's throw in comparison to the vastness of space.

The astronomers are documenting structural features, including bars. They want to know how many of the local galaxies have bars, as well as the environmental conditions in a galaxy that might influence the formation and structure of bars.

"Now, with Spitzer we can measure the precise shape and distribution of matter within the bar structures," said Sheth. "The bars are a natural product of cosmic evolution, and they are part of the galaxies' endoskeleton. Examining this endoskeleton for the fossilized clues to their past gives us a unique view of their evolution."

In the Spitzer image, shorter-wavelength infrared light has been assigned the color blue, and longer-wavelength light, red. The stars that appear blue in the central, bulge region of the galaxy are older; most of the gas, or star-making fuel, there was previously used up by earlier generations of stars. When galaxies are young and gas-rich, stellar bars drive gas toward the center, feeding star formation.

Over time, as the fuel runs out, the central regions become quiescent and star-formation activity shifts to the outskirts of a galaxy. There, spiral density waves and resonances induced by the central bar help convert gas to stars. The outer ring, seen here in red, is one such resonance area, where gas has been trapped and ignited into star-forming frenzy.

On older image of the galaxy shown below is based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA).


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Are Quasars at the Farthest Reaches of the Universe Dying?


Aeons ago, the universe was different: mergers of galaxies were common and gigantic black holes with masses equivalent to billions of times that of the Sun formed in their nuclei. As they captured the surrounding gas, these black holes emitted energy. Known as quasars, these very distant and tremendously high energy objects have local relatives with much lower energy whose existence raises numerous questions: are there also such “quiet” quasars at much larger distances? Are the latter dying versions of the former or are they completely different?

Light from distant quasars takes billions of years to reach us, so when we detect it we are actually looking at the universe as it was a long time ago. "Astronomers have always wanted to compare past and present, but it has been almost impossible because at great distances we can only see the brightest objects and nearby such objects no longer exist", says Jack W. Sulentic, astronomer at the Institute of Astrophysics of Andalusia (IAA-CSIC), who is leading the research. “Until now we have compared very luminous distant quasars with weaker ones closeby, which is tantamount to comparing household light bulbs with the lights in a football stadium”. Now we are able to detect the household light bulbs very far away in the distant past.

Quasars appear to evolve with distance: the farther away one gets, the brighter they are. This could indicate that quasars extinguish over time or it could be the result of a simple observational bias masking a different reality: that gigantic quasars evolving very quickly, most of them already extinct, coexist with a quiet population that evolves at a much slower rhythm but which our technological limitations do not yet allow us to research.

To solve this riddle it was necessary to look for low luminosity quasars at enormous distances and to compare their characteristics with those of nearby quasars of equal luminosity, something thus far almost impossible to do, because it requires observing objects about a hundreds of times weaker than those we are used to studying at those distances.

The tremendous light-gathering power of the GTC telescope, has recently enabled Sulentic and his team to obtain for the first time spectroscopic data from distant, low luminosity quasars similar to typical nearby ones. Data reliable enough to establish essential parameters such as chemical composition, mass of the central black hole or rate at which it absorbs matter.

"We have been able to confirm that, indeed, apart from the highly energetic and rapidly evolving quasars, there is another population that evolves slowly. This population of quasars appears to follow the quasar main sequence discovered by Sulentic and colleagues in 2000. There does not even seem to be a strong relation between this type of quasars, which we see in our environment and those “monsters” that started to glow more than ten billion years ago”, says Ascensión del Olmo another IAA-CSIC researcher taking part in the study.

They have, nonetheless, found differences in this population of quiet quasars. "The local quasars present a higher proportion of heavy elements such as aluminium, iron or magnesium, than the distant relatives, which most likely reflects enrichment by the birth and death of successive generations of stars,” says Jack W. Sulentic (IAA-CSIC). "This result is an excellent example of the new perspectives on the universe which the new 10 meter-class of telescopes such as GTC are yielding,” the researcher concludes.

J. W. Sulentic1, P. Marziani2, A. del Olmo1, D. Dultzin3, J. Perea1 & C.A. Negrete4. "GTC Spectra of z ≈ 2.3 Quasars: Comparison with Local Luminosity Analogues". Astronomy & Astrophysics. DOI:10.1051/0004-6361/201423975

The Chandra image at the top of the page shows a powerful jet shooting from quasar 3C273, providing an X-ray view into the area between 3C273's core and the beginning of the jet. High-powered jets driven from quasars, often at velocities very close to the speed of light, have long been perplexing for scientists. Instead of seeing a smooth stream of material driven from the core of the quasar, most optical, radio, and earlier X-ray observations have revealed inconsistent, "lumpy" clouds of gas.

The energy emitted from the jet in 3C273 probably comes from gas that falls toward a supermassive black hole at the center of the quasar, but is redirected by strong electromagnetic fields into a collimated jet. While the black hole itself is not observed directly, scientists can discern properties of the black hole by studying the jet. The formation of the jet from the matter that falls into the black hole is a process that remains poorly understood.

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Image of the Day: "At the Edge of the Cosmic Ocean" --Human Tracks on Mars

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“Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars," Carl Sagan, Cosmos. In February 2014, Curiosity’s MastCam instrument took this picture of rover tracks across a dune located in an area dubbed “Dingo Gap.”

"Given the recent Curiosity findings, past Martian life seems possible, and we should begin the difficult endeavor of seeking the signs of life," says Jack Mustard, chairman of the Science Definition Team and a professor at the Geological Sciences at Brown University. "However, no matter what we learn, we would make significant progress in understanding the circumstances of early life existing on Earth and the possibilities of extraterrestrial life."

Credit: NASA/JPL-Caltech/MSSS

« The Planck Spacecraft: An Epic New Picture of Our Invisible, Dark Universe | Main

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The Planck Spacecraft: An Epic New Picture of Our Invisible, Dark Universe


The Planck satellite was launched in May 2009. With the highest accuracy to date, it measures the remnants of the radiation that filled the Universe immediately after the Big Bang. It is the oldest light in the Universe, emitted when it was 380000 years old. This light is observed today as the cosmic microwave background (CMB). Its maximum intensity is at about 150 GHz (2 mm), and its temperature about 3K. The study of the CMB is currently a very active field of research in cosmology because it provides strong constraints on the cosmological models. In particular, observations of the CMB confirms the key prediction of the Big Bang model and, more precisely, of what cosmologists call the concordance model of cosmology.

Planck was designed to measure the emission from the entire sky at nine distinct wavelengths, ranging from the radio (1 cm) to the far-infrared (300 microns). Several distinct sources of emission ─ both of Galactic and extragalactic origin ─ contribute to the features observed in each of the nine images shown here. Radio emissions from the Milky Way are most prominent at the longest wavelengths, and thermal dust emission at the shortest. Other galaxies contribute to the mix, mostly as unresolved sources. In the middle of Planck’s wavelength range, the CMB dominates the sky at intermediate and high Galactic latitudes. The spectral and spatial signatures of all these sources are used to extract an all-sky image of the tiny temperature anisotropies of the CMB with unprecedented accuracy. The properties of these fluctuations are used to derive the parameters characterizing our Universe at early times.

The stack of images in the figure below shows in the center, the nine all-sky images ranging from 30 GHz (left) to 857 GHz (right); at far left, a combined view of all frequencies; at far right, the all-sky image of the temperature anisotropies of the CMB derived by Planck.

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Papers II to X in the series describe the huge dataset obtained from the Planck satellite and released in March 2013. Using this dataset, the Planck team established the new “cosmic recipe”, i.e., the relative proportions of the Universe’s constituent ingredients. Normal matter that makes up stars and galaxies contributes just 4.9% of the energy of the Universe. Dark matter, to date detected only indirectly by its gravitational influence on galaxies and galaxy clusters, is found to make up 26.8%, more than previous estimates. Conversely, dark energy, a mysterious force said to be responsible for accelerating the expansion of the Universe, accounts for 68.3%, less than previously thought. The Planck team also published a new value for the age of the Universe: 13.8 billion years.

The Planck team also studied the statistical properties of the CMB in great detail. Papers XXIII, XXIV, and XXVI explore the statistical distribution of its temperature anisotropies. There is no evidence of any deviations from isotropy on small angular scales. While the observations on small and intermediate angular scales agree extremely well with the model predictions, Planck has now provided the first indisputable evidence that the distribution of primordial fluctuations was not the same on all scales and that it comprises more structure than expected at larger scales. One anomalous signal appears as a substantial asymmetry in the CMB signal observed in the two opposite hemispheres of the sky, which is that one of the two hemispheres appears to have a significantly stronger signal on average. Among the other major results, Paper XXIII of the series explores how the Planck data can constrain theories of cosmic inflation; this paper currently puts the tightest constraints on inflation.

The CMB is not only a picture of the Universe taken 13.8 billion years ago, but it was also distorted during its journey because the CMB photons interacted with the large-scale structures that they traveled through (such as galaxy and galaxy clusters). In Paper XVII of the series, the team extracts from the Planck data a map of the gravitational lensing effect visible today in the CMB and covering the whole sky. The map published in this paper provides a new way to probe the evolution of structures in the Universe over its lifetime.

A byproduct of the Planck all-sky maps are catalogs of compact sources. Paper XXIX describes the production of the largest catalog of galaxy clusters based on the Sunyaev-Zeldovich effect, a distortion of the CMB spectrum caused by very energetic electrons in a galaxy cluster, which kick CMB photons to higher energies. This catalog was used to estimate cosmological constraints, as described in Paper XX.

With the 2013 release of the intensity signal measured during the 15 first months of observation, Planck data are providing new major advances in different domains of cosmology and astrophysics. In the very near future, the Planck Collaboration will release a new dataset that includes all of its observations in intensity and in polarization. This new dataset will be a lasting legacy for the community for many years to come.

Astronomy & Astrophysics is publishing a special feature of 31 articles describing the data gathered by Planck over 15 months of observations and released by ESA and the Planck Collaboration in March 2013. This series of papers presents the initial scientific results extracted from this first Planck dataset.

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Tuesday, 28 October 2014

"The Galaxy with No Central Black Hole" --Hubble Space Telescope Discovery (Today's Most Popular)


In the fall of 2012, astronomers using the NASA/ESA Hubble Space Telescope obtained a remarkable new view of a monster elliptical galaxy, with a core bigger than any seen before. Spanning a little over one million light-years, the galaxy is about ten times the diameter of the Milky Way galaxy. The bloated galaxy is a member of an unusual class of galaxies with an unusually diffuse core filled without any a concentrated peak of light around a central black hole.

"Expecting to find a black hole in every galaxy is sort of like expecting to find a pit inside a peach," explains astronomer Tod Lauer of the National Optical Astronomy Observatory in Tucson. "With this Hubble observation, we cut into the biggest peach and we can't find the pit. We don't know for sure that the black hole is not there, but Hubble shows that there's no concentration of stars in the core."

Viewing the core is like seeing a city with no center, just houses sprinkled across a vast landscape. An international team of astronomers used Hubble's Advanced Camera for Surveys and Wide Field Camera 3 to measure the amount of starlight across the galaxy, catalogued as 2MASX J17222717+3207571 but more commonly called A2261-BCG (short for Abell 2261 Brightest Cluster Galaxy). The Hubble observations revealed that the galaxy's puffy core, measuring about 10,000 light-years, is the largest yet seen.

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Astronomers using NASA's Hubble Space Telescope obtained a remarkable new view of this whopper of an elliptical galaxy that may have been puffed up by the actions of one or more black holes in its core. Spanning a little more than one million light-years, the galaxy is about 10 times the diameter of our Milky Way galaxy. The bloated galaxy is a member of an unusual class of galaxies with a diffuse core filled with a fog of starlight where there would normally be a concentrated peak of light around a central black hole. Viewing the core is like seeing a city with no downtown, just houses sprinkled across a vast landscape.

A galaxy's core size typically is correlated to the dimensions of its host galaxy, but in this case, the central region is much larger than astronomers would expect for the galaxy's size. In fact, the bloated core is more than three times larger than the center of other very luminous galaxies. Located three billion light-years away, the galaxy is the most massive and brightest galaxy in the Abell 2261 cluster.

Astronomers have proposed two possibilities for the puffy core. One scenario is that a pair of merging black holes gravitationally stirred up and scattered the stars. Another idea is that the merging black holes were ejected from the core. Left without an anchor, the stars began spreading out even more, creating the puffy-looking core.

Previous Hubble observations have revealed that supermassive black holes, with masses millions or billions times more than the Sun, reside at the centers of nearly all galaxies and may play a role in shaping those central regions.

Team leader Marc Postman of the Space Telescope Science Institute in Baltimore, said the galaxy stood out in the Hubble image. "When I first saw the image of this galaxy, I knew right away that it was unusual," Postman explained. "The core was very diffuse and very large. The challenge was then to make sense of all the data, given what we knew from previous Hubble observations, and come up with a plausible explanation for the intriguing nature of this particular galaxy."

The astronomers expected to see a slight cusp of light in the galaxy's center, marking the location of the black hole and attendant stars. Instead, the starlight's intensity remained fairly even across the galaxy. One possibility for the puffy core may be due to two central black holes orbiting each other.

These black holes collectively could have been as massive as several billion suns. One of the black holes would be native to the galaxy, while the second could have been added from a smaller galaxy that was gobbled up by the massive elliptical. In this scenario, stars circling in the giant galaxy's center came close to the twin black holes.

The stars were then given a gravitational boot out of the core. Each gravitational slingshot robbed the black holes of momentum, moving the pair ever closer together, until finally they merged, forming one supermassive black hole that still resides in the galaxy's center.

Another related possibility is that the black hole merger created gravity waves, which are ripples in the fabric of space. According to the theory of general relativity, a pair of merging black holes produces ripples of gravity that radiate away. If the black holes are of unequal mass, then some of the energy may radiate more strongly in one direction, providing the equivalent of a rocket thrust. The imbalance of forces would have ejected the merged black hole from the centre at speeds of millions of kilometres per hour, resulting in the rarity of a galaxy without a central black hole.

"The black hole is the anchor for the stars," explains Laurer, a co-author of the Hubble study. "If you take it out, all of a sudden you have a lot less mass. The stars aren't held together very well and they move outwards, enlarging the core even more." The team admits that the ejected black-hole scenario may sound far-fetched, "but that's what makes observing the Universe so intriguing—sometimes you find the unexpected," Postman says.

"This is a system that's interesting enough that it pushes against a lot of questions. Lauer added. "We have thought an awful lot about what black holes do. But we haven't been able to test our theories. This is an interesting place where a lot of the ideas we've had can come together and can be tested, fairly exotic ideas about how black holes may interact with each other dynamically and how they would affect the surrounding stellar population."

The team is conducting follow-up observations with the Very Large Array radio telescope in New Mexico. The astronomers expect material falling onto a black hole to emit radio waves, among other types of radiation. They will compare the VLA data with the Hubble images to more precisely pin down the location of the black hole, if it indeed exists.

The Abell 2261 cluster is part of a multi-wavelength survey, led by Postman, called the Cluster Lensing And Supernova survey with Hubble (CLASH). The survey probes the distribution of dark matter in 25 massive galaxy clusters.

Journal reference: Astrophysical Journal

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Supermassive Black Holes in the Centers of Galaxy Clusters Reveal Clues to Absence of Star Creation


Galaxy clusters are the largest objects in the universe, held together by gravity. These behemoths contain hundreds or thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees. This hot gas, which is the heftiest component of the galaxy clusters aside from unseen dark matter, glows brightly in X-ray light detected by Chandra. Over time, the gas in the centers of these clusters should cool enough that stars form at prodigious rates. However, this is not what astronomers have observed in many galaxy clusters.

“We knew that somehow the gas in clusters is being heated to prevent it cooling and forming stars. The question was exactly how,” said Irina Zhuravleva of Stanford University in Palo Alto, California, who led the study that appears in the latest online issue of the journal Nature. “We think we may have found evidence that the heat is channeled from turbulent motions, which we identify from signatures recorded in X-ray images.”

Chandra observations of the Perseus and Virgo galaxy clusters suggest turbulence may be preventing hot gas there from cooling, addressing a long-standing question of galaxy clusters do not form large numbers of stars. The same phenomenon that causes a bumpy airplane ride, turbulence, may be the solution to this long-standing mystery about stars’ birth, or the absence of it, according to a new study using data from NASA’s Chandra X-ray Observatory.

Prior studies show supermassive black holes, centered in large galaxies in the middle of galaxy clusters, pump vast quantities of energy around them in powerful jets of energetic particles that create cavities in the hot gas. Chandra, and other X-ray telescopes, have detected these giant cavities before. The latest research by Zhuravleva and her colleagues provides new insight into how energy can be transferred from these cavities to the surrounding gas. The interaction of the cavities with the gas may be generating turbulence, or chaotic motion, which then disperses to keep the gas hot for billions of years.

“Any gas motions from the turbulence will eventually decay, releasing their energy to the gas,” said co-author Eugene Churazov of the Max Planck Institute for Astrophysics in Munich, Germany. “But the gas won’t cool if turbulence is strong enough and generated often enough.”

The evidence for turbulence comes from Chandra data on two enormous galaxy clusters named Perseus and Virgo. By analyzing extended observation data of each cluster, the team was able to measure fluctuations in the density of the gas. This information allowed them to estimate the amount of turbulence in the gas.

“Our work gives us an estimate of how much turbulence is generated in these clusters,” said Alexander Schekochihin of the University of Oxford in the United Kingdom. “From what we’ve determined so far, there’s enough turbulence to balance the cooling of the gas. These results support the “feedback” model involving supermassive black holes in the centers of galaxy clusters. Gas cools and falls toward the black hole at an accelerating rate, causing the black hole to increase the output of its jets, which produce cavities and drive the turbulence in the gas. This turbulence eventually dissipates and heats the gas.

While a merger between two galaxy clusters may also produce turbulence, the researchers think that outbursts from supermassive black holes are the main source of this cosmic commotion in the dense centers of many clusters.

Chandra images of the Perseus and Virgo galaxy clusters at the top of the page suggest turbulence may be preventing hot gas there from cooling, addressing a long-standing question of galaxy clusters do not form large numbers of stars.

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Monday, 27 October 2014

Sun Observed Erupting with Extreme X-Class Flares


A large active region on the sun erupted with another X-class flare on Oct. 27, 2014 -- its fourth since Oct. 24. The flare peaked at 10:47 a.m. EDT. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc.

NASA's SDO captured images of two M-class flares erupting from the same region on the sun. The flare on the left peaked at 8:34 pm EDT on Oct. 26, 2014; the flare on the right peaked at 6:09 am EDT on Oct. 27, 2014. The images show EUV light of 131 Angstroms, which is typically colorized in teal.

Image Credit: NASA/SDO

Continuing a week's worth of substantial flares beginning on Oct.19, 2014, the sun emitted two mid-level solar flares on Oct. 26 and Oct. 27. The first peaked at 8:34 pm EDT on Oct. 26, 2014, and the second peaked almost 10 hours later at 6:09 am EDT on Oct. 27. NASA's Solar Dynamics Observatory, which constantly observes the sun, captured images of both flares.

Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

To see how this event may affect Earth, please visit NOAA's Space Weather Prediction Center at, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

The first flare was classified as an M7.1-class flare. The second flare was a bit weaker, classified as an M6.7-class.

M-class flares are one tenth as strong as X-class flares, which are the most intense flares. The number provides more information about its strength. An M2 is twice as intense as an M1, an M3 is three times as intense, etc.

The series of flares over the course of the previous week all erupted from a particularly large active region on the sun, labeled AR 12192 – the largest seen on the sun in 24 years. Active regions are areas of intense and complex magnetic fields that are often the source of solar flares.

Active regions are more common at the moment as we are in what's called solar maximum, which is the peak of the sun's activity, occurring approximately every 11 years.

The image at the top of the page from NASA's Solar Dynamics Observatory captured this image of an X-class solar flare bursting off the lower right side of the sun on Oct. 27, 2014. The image shows a blend of extreme ultraviolet light with wavelengths of 131 and 171 Angstroms.

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"New Star" Observed Morphing Into a Cosmic H-Bomb


On Aug. 14, 2013, the Japanese amateur astronomer Koichi Itagaki discovered a "new" star that was subsequently named Nova Delphinus 2013. Now, astronomers have observed the expanding thermonuclear fireball from a nova that erupted last year in the constellation Delphinus with unprecedented clarity. The observations produced the first images of a nova during the early fireball stage and revealed how the structure of the ejected material evolves as the gas expands and cools. It appears the expansion is more complicated than simple models previously predicted, scientists said.

A nova occurs following the buildup of a thin layer of hydrogen on the surface of a white dwarf, a highly evolved star with the diameter of the Earth and the mass of the sun. The hydrogen is provided by a close companion, which is a normal star in a binary star system, where the two stars orbit about their center of mass. When this hydrogen "ocean" is perhaps 200 meters (about 650 feet), the enormous surface gravity of the white dwarf produces pressures at the bottom of the hydrogen layer sufficient to trigger thermonuclear fusion, essentially a stellar H-bomb.

The light from the explosion will significantly exceed the star's normal brightness and the object may suddenly appear to the naked eye in a location not previously noted to have a bright star. Over ensuing weeks, the star slowly fades as the fireball expands, cools and dissipates.

Within 15 hours of the discovery of Nova Del 2013 and within 24 hours of the actual explosion, astronomers pointed the telescopes of the CHARA Array (Center for High Angular Resolution Astronomy ) at Georgia State University's toward the nova to image the fireball and measure its size and shape. The size of Nova Del 2013 was measured on 27 nights over the course of two months. The first measurement represents the earliest size yet obtained for a nova event. The results of these observations, carried out by 37 researchers from 17 institutions and led by Georgia State astronomer Gail Schaefer, are published in the current issue of Nature.

The CHARA facility is on the grounds of historic Mount Wilson Observatory in the San Gabriel Mountains of Southern California and is operated by Georgia State. The CHARA Array uses the principles of optical interferometry to combine the light from six telescopes to create images with very high resolution, equivalent to a telescope with a diameter of more than 300 meters. This makes it capable of seeing details far smaller in angular extent than traditional telescopes on the ground or in space. It has the power to resolve an object the size of a U.S nickel on top of the Eiffel tower in Paris from the distance of Los Angeles, Calif.

Measuring the expansion of the nova allowed the researchers to determine that Nova Del 2013 is at a distance of 14,800 light years from the sun. This means that, while the explosion was witnessed here on Earth last August, it actually took place nearly 15,000 years ago.

During the first CHARA observation, the physical size of the fireball was roughly the size of the Earth's orbit. When last measured 43 days after the detonation, it had expanded nearly 20-fold, at a velocity of more than 600 kilometers per second, to nearly the size of Neptune's orbit, the outermost planet in our solar system.

Images of the fireball were created from the interferometric measurements using the University of Michigan Infrared Beam Combiner (MIRC), an instrument that combines all six telescopes of the CHARA Array simultaneously to create images. The observations reveal the explosion was not precisely spherical and the fireball had a slightly elliptical shape. This provides clues to understanding how material is ejected from the surface of the white dwarf during the explosion.

The CHARA observations also showed the outer layers became more diffuse and transparent as the fireball expanded. After about 30 days the researchers saw evidence for a brightening in the cooler, outer layers, potentially caused by the formation of dust grains that emit light at infrared wavelengths.

Thousands of novae have been discovered since the first one was recorded in 1670, but it has only become possible in the last decade or so to image the earliest stages of the explosion thanks to the high resolution achieved through interferometry. Studying how the structure of novae changes at the earliest stages brings new insights to theoretical models of novae eruptions.

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Image of the Day: Extreme Elliptical Galaxy --"Twice as Many Stars as the Milky Way"


A fully developed elliptical galaxy is a gas-deficient gathering of ancient stars theorized to develop from the inside out, with a compact core marking its beginnings. This past August, for the first time, astronomers caught a glimpse of the earliest stages of massive galaxy construction. The building site is a dense galactic core blazing with the light of millions of newborn stars that are forming at a ferocious rate. Although only a fraction of the size of the Milky Way, the tiny powerhouse galactic core already contains about twice as many stars as our own galaxy, all crammed into a region only 6,000 light-years across. The Milky Way is about 100,000 light-years across.

The discovery was made possible through combined observations from NASA’s Hubble and Spitzer space telescopes, the W.M. Keck Observatory in Mauna Kea, Hawaii, and the European Space Agency's Herschel space observatory, in which NASA plays an important role.Because the galactic core is so far away, the light of the forming galaxy that is observable from Earth was actually created 11 billion years ago, just 3 billion years after the Big Bang.

“I think our discovery settles the question of whether this mode of building galaxies actually happened or not,” said team-member Pieter van Dokkum of Yale University. “The question now is, how often did this occur? We suspect there are other galaxies like this that are even fainter in near-infrared wavelengths. We think they’ll be brighter at longer wavelengths, and so it will really be up to future infrared telescopes such as NASA’s James Webb Space Telescope to find more of these objects.”

“We really hadn’t seen a formation process that could create things that are this dense,” explained Erica Nelson of Yale University in New Haven, Connecticut, lead author of the study. “We suspect that this core-formation process is a phenomenon unique to the early universe because the early universe, as a whole, was more compact. Today, the universe is so diffuse that it cannot create such objects anymore.”

In addition to determining the galaxy’s size from the Hubble images, the team dug into archival far-infrared images from Spitzer and Herschel. This allowed them to see how fast the galaxy core is creating stars. Sparky produced roughly 300 stars per year, compared to the 10 stars per year produced by our Milky Way.

“They’re very extreme environments,” Nelson said. “It’s like a medieval cauldron forging stars. There’s a lot of turbulence, and it’s bubbling. If you were in there, the night sky would be bright with young stars, and there would be a lot of dust, gas, and remnants of exploding stars. To actually see this happening is fascinating.”

Astronomers theorize that this frenzied star birth was sparked by a torrent of gas flowing into the galaxy’s core while it formed deep inside a gravitational well of dark matter, invisible cosmic material that acts as the scaffolding of the universe for galaxy construction.

Observations indicate that the galaxy had been furiously making stars for more than a billion years. It is likely that this frenzy eventually will slow to a stop, and that over the next 10 billion years other smaller galaxies may merge with Sparky, causing it to expand and become a mammoth, sedate elliptical galaxy.

The image at the top pf the page shows a representative elliptical galaxy NGC 1132 and its surrounding region combines data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The blue/purple in the image is the x-ray glow from hot, diffuse gas detected by Chandra. Hubble's data reveal a giant foreground elliptical galaxy, plus numerous dwarf galaxies in its neighborhood, and many much more distant galaxies in the background.

Astronomers have dubbed NGC 1132 a "fossil group" because it contains an enormous amount of dark matter, comparable to the dark matter found in an entire group of galaxies. Also, the large amount of hot gas detected by Chandra is usually found for groups of galaxies, rather than a single galaxy.

The origin of such fossil-group systems remains a puzzle. They may be the end-products of the complete merging of groups of galaxies. Or, they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.

Elliptical galaxies are smooth and featureless. Containing hundreds of millions to trillions of stars, they range from nearly spherical to very elongated shapes. Their overall yellowish color comes from the aging stars. Because elliptical galaxies do not contain much cool gas, they can no longer make large numbers of new stars.

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Search for Pulsars Emitting Energy Beams of 10 Million Suns Heats Up

Hubble and Chandra composite view of NGC 922 (1)

Recently, a team of astronomers reported discovering a pulsating star that appears to shine with the energy of 10 million suns. The find, which was announced in Nature, is the brightest pulsar – a type of rotating neutron star that emits a bright beam of energy that regularly sweeps past Earth like a lighthouse beam – ever seen. But what are the odds finding another one?

According to one of the paper's authors, chances are good now that they know what to look for. Deepto Chakrabarty of the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology says he is optimistic that astronomers will find additional ultra-bright pulsars now that they know such objects exist.

"Detecting pulsations in faint sources is challenging, because the X-ray data are not always collected with sufficiently high time-resolution to make the measurement," he says. "Our discovery will now justify the additional effort required to make such timing observations."

Astronomers previously thought that this type of "ultraluminous X-ray source" was likely to be made up of black holes five to 50 times more massive than our sun, radiating energy as they pull in nearby matter. This discovery that at least one ULX source is in fact a pulsar brings that understanding into question.

"Black holes are unable to produce coherent pulsations like what we are seeing here," Chakrabarty says. The discovery is even more surprising because pulsars by nature are not very massive objects and so have always been assumed capable of only relatively moderate X-ray signals. The newly discovered pulsar is far brighter than previously thought possible.

Chakrabarty says he believes the mysteries of how a pulsar could beam so bright can be solved through additional experimental observations – and with the assistance of theorists.

"It is clear that some sort of specialized beaming may be going on here, but coming up with a sensible and self-consistent picture may be a challenge," he says. "Observing some more examples of ULX pulsars could be very helpful in sorting this out, giving us some different sets of system parameters to work with."

The image at ythe top of the page shows galaxy NGC 922’s unusual form --the result of a cosmic bullseye millions of years ago. A smaller galaxy, catalogued as 2MASXI J0224301-244443, plunged right through the heart of NGC 922 and shot out the other side. In wide-field views of the NGC 922, the small interloper can be still be seen shooting away from the scene of the crash. Observing with NASA's Chandra X-ray Observatory reveals more chaos in the form of ultraluminous X-ray sources dotted around the galaxy.

More of Deepto Chakrabarty's thoughts on how this new result can align with current knowledge of both ULX sources and pulsars can be found in this Kavli Foundation conversation:

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Saturday, 25 October 2014

"Unlocking the Secrets of Our Origins" --A SciFi VIDEO from the European Space Agency


Imagine: with a wasteland as their canvas, a Master and his young Apprentice set about turning rubble into planets and moons, asteroids and comets. They levitate the worlds above their heads, spinning them in orbit around their symbolic Sun.

“What is the key to life on Earth?” asks the Master. The Apprentice shakes her head. The answer is obvious: water. For a long time, the origins of water, and indeed life on our planet remained an absolute mystery. So we began searching for answers beyond Earth,” the Master continues. “In time we turned to comets. One trillion celestial balls of dust, ice, complex molecules, left over from the birth of our Solar System. Once thought of as messengers of doom and destruction, and yet so enchanting. And we were to catch one: a staggeringly ambitious plan.”

Science fiction? No – science fact.As Tomek Bagiński’s short film Ambition makes clear, it is the essence of what it means to be human, to attempt difficult things, to reach for seemingly impossible goals, to learn, adapt and evolve.

And at the heart of this film is Rosetta, ESA’s real mission to rendezvous with, escort and land on a comet. A mission that began as a dream, but that after decades of planning, construction and flight through the Solar System, has arrived at its goal.

Its aim? To unlock the secrets hidden within the icy treasure chest for 4.6 billion years. To study its make-up and its history. To search for clues as to our own origins.

From 100 km distance, to 50, 30 and then, defying all expectations, to just 10 km, Rosetta continues to captivate and intrigue with every image and every data packet returned. It will rewrite the textbooks of cometary science.

But there is more, an even greater challenge, another ambitious first: to land on the comet. The stage is set. The date: 12 November 2014.


“As a science fiction writer, it’s hard to think of a more stirring theme than the origin and ultimate destiny of life in the Universe,” says Alastair Reynolds.

“With the arrival of Rosetta at 67P/Churyumov–Gerasimenko – an astonishing, audacious technical achievement, literally the stuff of science fiction – we are on the brink of a bold new chapter in our understanding of our place in the Universe.”

“Rosetta is less than 10 km from a comet, and both are racing through space at over 60 000 km/h,” says Matt Taylor, ESA’s Rosetta project scientist. “Next month, we’ll be attempting to land on the comet, and with our orbiting spacecraft, we’ll continue to keep pace with the comet for another year or more, watching how it evolves over time.

“All of this is new and unique and has never been done before. It may sound like science fiction, but it’s a reality for the teams that have dedicated their entire lives to this mission, driven to push the boundaries of our technology for the benefit of science and to seek answers to the biggest questions regarding our Solar System’s origins.”

Ambition is a collaborative project of ESA and Platige Image. Directed by Tomek Baginski and starring Aiden Gillen and Aisling Franciosi, it was shot on location in Iceland, and screened on 24 October during the British Film Institute’s celebration of Sci-Fi: Days of Fear and Wonder, at the Southbank, London.

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"Titan's Alien Ice Cloud Similar to Those Above Earth's Poles" --NASA (Weekend Feature)


"The idea that methane clouds could form this high on Titan is completely new," said Carrie Anderson, a Cassini participating scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. "Nobody considered that possible before."

NASA scientists have identified an unexpected high-altitude methane ice cloud on Saturn's moon Titan that is similar to exotic clouds found far above Earth's poles. This lofty cloud, imaged by NASA's Cassini spacecraft, was part of the winter cap of condensation over Titan's north pole. Now, eight years after spotting this mysterious bit of atmospheric fluff, researchers have determined that it contains methane ice, which produces a much denser cloud than the ethane ice previously identified there.

The image above shows polar clouds at Titan (left) and on Earth (right). The cloud in the stratosphere over Titan’s north pole (left) is similar to Earth’s polar stratospheric clouds (right). NASA scientists found that Titan’s cloud contains methane ice, which was not previously thought to form in that part of the atmosphere. Cassini first spotted the cloud in 2006.

Methane clouds were already known to exist in Titan's troposphere, the lowest layer of the atmosphere. Like rain and snow clouds on Earth, those clouds form through a cycle of evaporation and condensation, with vapor rising from the surface, encountering cooler and cooler temperatures and falling back down as precipitation. On Titan, however, the vapor at work is methane instead of water.

The newly identified cloud instead developed in the stratosphere, the layer above the troposphere. Earth has its own polar stratospheric clouds, which typically form above the North Pole and South Pole between 49,000 and 82,000 feet (15 to 25 kilometers) -- well above cruising altitude for airplanes. These rare clouds don't form until the temperature drops to minus 108 degrees Fahrenheit (minus 78 degrees Celsius).

Other stratospheric clouds had been identified on Titan already, including a very thin, diffuse cloud of ethane, a chemical formed after methane breaks down. Delicate clouds made from cyanoacetylene and hydrogen cyanide, which form from reactions of methane byproducts with nitrogen molecules, also have been found there.

But methane clouds were thought unlikely in Titan's stratosphere. Because the troposphere traps most of the moisture, stratospheric clouds require extreme cold. Even the stratosphere temperature of minus 333 degrees Fahrenheit (minus 203 degrees Celsius), observed by Cassini just south of the equator, was not frigid enough to allow the scant methane in this region of the atmosphere to condense into ice.

What Anderson and her Goddard co-author, Robert Samuelson, noted is that temperatures in Titan's lower stratosphere are not the same at all latitudes. Data from Cassini's Composite Infrared Spectrometer and the spacecraft's radio science instrument showed that the high-altitude temperature near the north pole was much colder than that just south of the equator.

It turns out that this temperature difference -- as much as 11 degrees Fahrenheit (minus 12 degrees Celsius) -- is more than enough to yield methane ice.

Other factors support the methane identification. Initial observations of the cloud system were consistent with small particles composed of ethane ice. Later observations revealed some regions to be clumpier and denser, suggesting that more than one ice could be present. The team confirmed that the larger particles are the right size for methane ice and that the expected amount of methane -- one-and-a-half percent, which is enough to form ice particles -- is present in the lower polar stratosphere.

The mechanism for forming these high-altitude clouds appears to be different from what happens in the troposphere. Titan has a global circulation pattern in which warm air in the summer hemisphere wells up from the surface and enters the stratosphere, slowly making its way to the winter pole. There, the air mass sinks back down, cooling as it descends, which allows the stratospheric methane clouds to form.

"Cassini has been steadily gathering evidence of this global circulation pattern, and the identification of this new methane cloud is another strong indicator that the process works the way we think it does," said Michael Flasar, Goddard scientist and principal investigator for Cassini's Composite Infrared Spectrometer (CIRS).

Like Earth's stratospheric clouds, this methane cloud was located near the winter pole, above 65 degrees north latitude. Anderson and Samuelson estimate that this type of cloud system -- which they call subsidence-induced methane clouds, or SIMCs for short -- could develop between 98,000 to 164,000 feet (30 to 50 kilometers) in altitude above Titan's surface.

"Titan continues to amaze with natural processes similar to those on the Earth, yet involving materials different from our familiar water," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "As we approach southern winter solstice on Titan, we will further explore how these cloud formation processes might vary with season."

The results of this study are available online in the journal Icarus.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The CIRS team is based at Goddard. The radio science team is based at JPL.

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"The Ring of Fire" --X-Ray Footage of Thursday's Solar Eclipse (VIDEO)


The moon passed between the Earth and the sun on Thursday, Oct. 23. While avid stargazers in North America looked up to watch the spectacle, the best vantage point was several hundred miles above the North Pole.The Hinode spacecraft was in the right place at the right time to catch the solar eclipse. What’s more, because of its vantage point Hinode witnessed a “ring of fire” or annular eclipse.

An annular eclipse occurs when the moon passes directly in front of the sun but doesn’t cover it completely because the moon appears too small. (The apparent size of the moon depends on its distance from Earth or, in this case, the spacecraft.) About one-third of all solar eclipses are annular.

“This is only the second annular eclipse Hinode has witnessed since it launched in 2006,” says astrophysicist Patrick McCauley of the Harvard-Smithsonian Center for Astrophysics.

The XRT was developed and built by the Smithsonian Astrophysical Observatory and the Japan Aerospace Exploration Agency. Hinode’s X-ray Telescope is the highest resolution solar X-ray telescope ever flown.

The XRT collects X-rays emitted from the sun’s corona - the hot, tenuous outer layer that extends from the sun’s visible surface into the inner solar system. Gas in the solar corona reaches temperatures of millions of degrees. The energy source that heats the corona is a puzzle. The sun’s surface is only 10,000 degrees Fahrenheit, while the corona is more than 100 times hotter.

“We are very interested in studying solar flares,” adds McCauley. “Flares are most dramatic in X-rays and we’re using the X-ray Telescope to better understand the physical mechanisms that drive flares so that they might someday be forecasted.”

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Friday, 24 October 2014

China Launches its 1st Space Mission to the Moon and Back

China launched its first space mission to the moon and back early Friday, authorities said, the latest step forward for Beijing's ambitious program to one day land a Chinese citizen on the Earth's only natural satellite. The unnamed, unmanned probe will travel to the moon, fly around it and head back to Earth, re-entering the atmosphere and landing, the State Administration of Science, Technology and Industry for National Defence (SASTIND) said in a statement. The module will be 413,000 kilometres from Earth at its furthest point on the eight-day mission.

"The first stage of the first return journey test in China's moon probe program has been successful," it said after the launch, from the Xichang space base in the southwestern province of Sichuan.

The official Xinhua news agency said it would re-enter the atmosphere at 11.2 kilometres per second (25,000 mph) before slowing down -- a process that generates extremely high temperatures -- and landing in northern China's Inner Mongolia region.

The mission is intended to test technology to be used in the Chang'e-5, China's fourth lunar probe, which aims to gather samples from the moon's surface and will be launched around 2017, SASTIND said previously. Beijing sees its multi-billion-dollar space program as a marker of its rising global stature and mounting technical expertise, as well as evidence of the ruling Communist Party's success in turning around the fortunes of the once poverty-stricken nation.

The military-run project has plans for a permanent orbiting station by 2020 and eventually to send a human to the moon.

China currently has a rover, the Jade Rabbit, on the surface of the moon.

The craft, launched as part of the Chang'e-3 lunar mission late last year, has been declared a success by Chinese authorities, although it has been beset by mechanical troubles.

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Strange Triple Asteroid System Observed


“Combined observations from small and large telescopes provide a unique opportunity to understand the nature of this complex and enigmatic triple asteroid system,” said Franck Marchis, senior research scientist at the Carl Sagan Center of the SETI Institute. “Thanks to the presence of these moons, we can constrain the density and interior structure of an asteroid, without the need for a spacecraft’s visit. Knowledge of the internal structure of asteroids is key to understanding how the planets of our solar system formed.”

Combining observations from the world’s largest telescopes with those from smaller instruments used by amateur astronomers, a team of scientists has discovered that the large main-belt asteroid (87) Sylvia has a complex interior. This has been deduced by using the motions of the two moons orbiting the main asteroid as probes of the object’s density distribution. The complex structure is probably linked to the way the multiple system was formed.

The findings were announced last year at the 45th annual Division of Planetary Sciences meeting in Denver, Colorado and were published last month in the journal Icarus.

The asteroid (87) Sylvia is the first known to have two moons. One moon was discovered in 2001, and the second was found in 2005 by a team led by Franck Marchis. Since then, the team has continued to make new observations of the system using 8 to 10 m-class telescopes, including those at the Keck Observatory, the European Southern Observatory, and Gemini North.

The differentiated interior of the asteroid is shown in a cutaway diagram. The primary asteroid may have a dense, regularly-shaped core, surrounding by fluffy or fractured material. The outer moon, named Romulus, is known to be strongly elongated, possibly having two lobes, as suggested by a recently observed occultation recorded by amateur astronomers.

The article “Physical and dynamical properties of the main belt triple Asteroid (87) Sylvia, published last month in Icarus, is co-authored by J. Berthier, F. Vachier, B. Carry from IMCCE-Obs de Paris, J. Durech from Charles University, Prague, and F. Marchis from the SETI Institute and Obs. de Paris.

Reference: Berthier, J., F. Vachier, F. Marchis, J. Ďurech, and B. Carry. 2014. “Physical and Dynamical Properties of the Main Belt Triple Asteroid (87) Sylvia.” Icarus 239 (September): 118–30. doi:10.1016/j.icarus.2014.05.046.

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Thursday, 23 October 2014

Early Earth: "Life Could Have Reseeded the Surface Multiple Times During Bombardment by Comets and Asteroids"


No-one knows when life first established a firm foothold on Earth. Ask around in the scientific community, though, and you’ll probably hear that the surface of early Earth, before about 3.8 billion years ago, was too hostile an environment for even a lowly microbe to set up shop. But new research by NASA Astrobiologists shows that life appeared to have been flourishing during the period of the Late Heavy Bombardment, at a time when Earth’s surface was thought to be uninhabitable.

The evidence appears to be a banded iron rock formation, or BIF, from Akilia Island in West Greenland. BIFs were deposited on Earth’s ocean floors during the first 2 billion years of the planet’s history. Iron and oxygen present in the oceans combined to form rust, which settled to the sea floor in layered sediments. Movements of the Earth’s crust later pushed some of these sediments to the surface, where they can now be studied.

It’s not possible to date the Akilia BIF sediments directly because they have undergone metamorphism – pressure cooking – so that traditional radioactive dating techniques cannot be used to determine their age. But jutting into these sediments are younger igneous rocks that can be accurately dated with these techniques.

An earlier analysis of this igneous rock, performed by a group headed by Dr. Allen Nutman of the Australian National University, put its age at 3.85 billion years. And because the igneous rock intrudes into the banded iron formation, it must have formed later than the sediments did. So the Akilia sediments must have been formed at least 3.85 billion years ago. Exactly how old they are, there is no way to know. But they are more ancient than any other sedimentary rocks found so far on Earth.

Rocks this old are rare on Earth because tectonic recycling action has crushed, buried and melted all of the material that formed the Earth’s crust during its first half-billion years of existence. Finding sedimentary rocks this old is important to geologists because they provide invaluable clues about what Earth was like in its early years.

Few people dispute the notion that between 4.1 and 3.8 billion years ago, our planet was heavily bombarded by debris from space, a period known as the Late Heavy Bombardment. If you look up at a full moon on a clear night, you see that its surface is riddled with impact craters. Scientists who study the size and distribution of those craters see clear evidence that the Moon underwent an intense period of impacts between 4.1 and 3.8 billion years ago. Although no craters from this time remain on Earth, because the Earth and Moon are so near each other, the assumption is that Earth suffered a similar fate.

Ariel D. Anbar, an Assistant Professor in the Department of Earth and Environmental Sciences at the University of Rochester, working with Gail L. Arnold, a graduate student, decided to look for traces of this bombardment in the Akilia sediments. Comets and asteroids contain greater quantities of the chemical element iridium than does the Earth’s crust. So Anbar and Arnold, members of the NASA Astrobiology Institute (NAI), probed the Akilia sediments for abnormally high traces of iridium.

They didn’t find them. “Our naive expectation going in,” explained Anbar, was that “these sediments date from this bombardment period, so we should see evidence of the bombardment in them, right? So we looked for iridium in these rocks and didn’t find any. They were clean as a whistle.”

But earlier study of the Akilia sediments by one of Anbar’s collaborators, Steve Mojzsis, had turned up a very different type of signature in the Akilia formation – a signature of biological activity. Mojzsis, also a member of the NAI, performed his analysis of the Akilia sediments while at the University of California San Diego.

Carbon atoms come in two distinct forms, or isotopes. Carbon-12 atoms, the lighter of the two, contain 6 neutrons; carbon-13 atoms contain 7 neutrons. Microorganisms that take in carbon dioxide prefer to use the lighter carbon-12 atoms to construct the organic building blocks of which they are made.

When ancient ocean-dwelling organisms died, the carbon that was formerly part of their living tissue settled to the ocean floor, becoming part of the sedimentary material deposited there. When Mojzsis found that the Akilia sedimentary rock samples contained higher-than-normal quantities of carbon-12, he concluded that biological activity must have been taking place at the time the sediments were formed – at least 3.85 billion years ago.

So Anbar, Arnold and Mojzsis were faced with seemingly contradictory evidence. Life appeared to have been flourishing during the period of the Late Heavy Bombardment, at a time when Earth’s surface was thought to be uninhabitable. And traces of the bombardment were nowhere to be found in the Akilia rocks.

The solution lay in quantifying more carefully the effects of bombardment, using models developed by NAI member Kevin Zahnle at the NASA Ames Research Center. The essence of these models is that they treat the bombardment as a series of impact episodes, rather than assuming continuous pummeling of the Earth. They also take into account that smaller impact events are far more common than larger ones.

The Akilia sediments would not be expected to contain telltale traces of extraterrestrial iridium unless a massive asteroid had slammed into the Earth, spewing iridium into the global environment, precisely during the period when the Akilia formation was being deposited. Zahnle’s models indicate, however, that even during the Late Heavy Bombardment, such massive impacts were rare – too rare for there to be much chance of seeing their signs in sediments like those found on Akilia Island. So it made perfect sense that the sediments didn’t contain elevated levels of iridium.

Anbar and his colleagues reason that if the bombardment had a smaller-than-expected effect on the composition of sediments, it may also have had a smaller-than-expected effect on early life. Although small impacts were more common during the Late Heavy Bombardment than at any time since then, each such impact would destroy life at the surface only in one small area, not globally. Only the rarest, most massive impacts had the potential to wipe out all life on the planet’s surface.

Zahnle’s models indicate such impacts occurred only once every ten to one hundred million years. Moreover, the worst of their effects lasted for only about ten thousand years, after which time conditions on the Earth’s surface returned to normal. “So during most of this violent period of Earth’s history,” says Anbar, “the Earth’s surface – if you’re a microbe, anyway – was a perfectly balmy place to be. Which runs contrary to this picture that is out there that this was a very inhospitable period of time for life.”

That still leaves open one important question: Where could life hang out in safety during those rare, massive impact events that caused the surface literally to boil away? One suggestion is that hydrothermal vents might have filled that role. If life migrated down to these vents – or perhaps even began there – it could have continued on during major impact events, oblivious to what was going on the surface. And when the environment topside returned to habitability, life could have moved back up and recolonized the surface.

“So as long as microorganisms had places on the Earth where they’d be sheltered from really massive impact events,” concluded Anbar, “there’s no reason that they couldn’t have repopulated the surface multiple times. And therefore there’s no reason not to expect to find evidence of life if you find sediments from the earth’s surface during the period of heavy bombardment.”

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