Nov 19, 2011

Alien Life May Live in Various Habitable Zones

Of the approximately 1,500 exoplanets found so far, only a few are in the so-called habitable zone around their parent star. It's also called the "Goldilocks zone," a coveted sweet-spot where the amount of radiation coming from a star is "just right" for liquid water to exist on the surface of a rocky planet.

For example, Earth is within the present habitable zone around our sun, which is a comparatively narrow swath 18 million miles across.

Enthusiasm about finding other worlds nestled inside other stars' habitable zones is so strong that in 2008 a radio message was beamed to a planet known to exist in the habitable zone of the red dwarf star Gliese 581, located 20 light-years away.

The signal contains 501 greetings that were selected through a competition on a social networking site.

The tight noose defined by a habitable zone is one of the important variables in the famous Drake Equation, which tries to estimate the number of extraterrestrial civilizations in our galaxy.

The habitable zone concept was widely popularized in the mid 1970s by astronomer Michael Hart. He used it to argue that Earth was the only home for intelligent life in the galaxy. In fact, Hart’s own calculation from the Drake Equation came up with a probability of .000000000000000000000000000000000001 percent of there being intelligent life elsewhere in the galaxy.

But we've come a long way since then with the discovery of extremeophiles tucked away in every nook and cranny of Earth. Add to that a more pragmatic definition of life as simply being a self-sustaining chemical system that undergoes Darwinian evolution.

Life as we know it couldn't have started without water. Water provides a nurturing environment for complex molecules to form and organize themselves. But water is a liquid over a temperature range that is present in only a very small number of objects in the universe. Hence, the idea of a narrow habitable zone.

Perhaps so, but in the cosmological context there's no obvious reason why life has to be exclusively dependent on a water-based environment. Life could be so opportunistic and adaptable it may simply work with whatever liquid is at hand. Alternative solvents considered by astrobiologists include dihydrogen (a simple molecule composed of two hydrogen atoms), sulfuric acid, dinitrogen, formamide, and methane, among others.

If so, this antiquates the notion of a narrow habitable zone encircling billions of stars in our galaxy. Depending on your flavor of life, there could be multiple habitable zones around the sun and other stars.

Move out to one billion miles from the sun and you're in a potential "methane habitable zone." This is where the giant Saturnian moon Titan is. Titan has rain, rivers, and giant lakes of freestanding liquid. It's not water, which is rock-hard at Titan's surface temperature of minus 300 degrees Fahrenheit, but instead it is liquid methane and ethane.

Astrobiologist Chris McKay of NASA's Ames Research Center has hypothesized the presence of a "cryolife" in Titan. The organisms would breath hydrogen instead of oxygen, use acetylene in place of glucose, and exhale methane. This scenario could certainly explain some of Titans odd chemistry.

Titan may also have an ammonia-water subsurface ocean. Ammonia could be as gentle to organic molecules at least as well as water is.

McKay has considered the feasibility of methane habitable zones around the most common stars in our galaxy, red dwarfs. These stars are much cooler than the sun and so the habitable zones could be as close to their stars as Earth is our sun, or even closer.

If Titan orbited a red dwarf, more light for powering life would reach the surface because Titan’s atmospheric haze is more transparent to infrared light.

McKay thinks there could be many Titan-like worlds beyond our solar system that have surface methane lakes and oceans.

Therefore, the whole idea of just one type of habitable zone in the galaxy may be terribly geocentric thinking. On the other hand, could intelligent life arise from other exotic biochemistries?

Read more at Discovery News

New Revolutionary Material Can Be Worked Like Glass

A common feature of sailboards, aircraft and electronic circuits is that they all contain resins used for their lightness, strength and resistance. However, once cured, these resins can no longer be reshaped. Only certain inorganic compounds, including glass, offered this possibility until now. Combining such properties in a single material seemed impossible until a team led by Ludwik Leibler, CNRS researcher at the Laboratoire "Matière Molle et Chimie" (CNRS/ESPCI ParisTech), developed a new class of compounds capable of this remarkable feat. Repairable and recyclable, this novel material can be shaped at will and in a reversible manner at high temperature.

And, quite surprisingly, it also retains certain properties specific to organic resins and rubbers: it is light, insoluble and difficult to break. Inexpensive and easy to produce, this material could be used in numerous industrial applications, particularly in the automobile, aeronautics, building, electronics and leisure sectors. This work is published on 18 November 2011 in Science.

Replacing metals by lighter but just as efficient materials is a necessity for numerous industries, such as aeronautics, car manufacturing, building, electronics and sports industry. Due to their exceptional mechanical strength and thermal and chemical resistance, composite materials based on thermosetting resins are currently the most suitable. However, such resins must be cured in situ, using from the outset the definitive shape of the part to be produced. In fact, once these resins have hardened, welding and repair become impossible. In addition, even when hot, it is impossible to reshape parts in the manner of a blacksmith or glassmaker.

This is because glass (inorganic silica) is a unique material: once heated, it changes from a solid to a liquid state in a very progressive manner (glass transition), which means it can be shaped as required without using molds. Conceiving highly resistant materials that can be repaired and are infinitely malleable, like glass, is a real challenge both in economic and ecological terms. It requires a material that is capable of flowing when hot, while being insoluble and neither as brittle nor as "heavy" as glass.

From ingredients that are currently available and used in industry (epoxy resins, hardeners, catalysts, etc.), researchers from the Laboratoire "Matière Molle et Chimie" (CNRS/ESPCI ParisTech) developed a novel organic material made of a molecular network with original properties: under the action of heat, this network is capable of reorganizing itself without altering the number of cross-links between its atoms. This novel material goes from the liquid to the solid state or vice versa, just like glass. Until now, only silica and some inorganic compounds were known to show this type of behavior. The material thus acts like purely organic silica. It is insoluble even when heated above its glass transition temperature.

Remarkably, at room temperature, it resembles either hard or soft elastic solids, depending on the chosen composition. In both cases, it has the same characteristics as thermosetting resins and rubbers currently used in industry, namely lightness, resistance and insolubility. Most importantly, it has a significant advantage over the latter as it is reshapeable at will and can be repaired and recycled under the action of heat. This property means it can undergo transformations using methods that cannot be envisaged either for thermosetting resins or for conventional plastic materials. In particular, it makes it possible to produce shapes that are difficult or even impossible to obtain by molding or for which making a mold is too expensive for the envisaged purpose.

Read more at Science Daily

Nov 18, 2011

Climate Change May Have Doomed Neanderthals

When climate took a turn toward the cold tens of thousands of years ago, both Neanderthals and early humans started traveling further distances to find food, found a new study.

As a result, the two groups encountered each other often.. And a consequent boom in inter-species liaisons eventually led to the extinction of Neanderthals.

While much of the theory remains controversial, the study adds to growing evidence that Neanderthals developed advanced cultures and that they adapted to changes in the environment just like early humans did.

The study also hints at what's to come if climate change forces modern cultures to blend, as their homes become inhospitable from drought, flooding or severe weather.

"We are increasingly finding evidence of sophisticated behavior among Neanderthals, and now the question is: If they were so smart, why did they become extinct?" said Michael Barton, an anthropologist at Arizona State University in Tempe.

"Our answer is that they became extinct because they were so smart, not in spite of it," he said. "They were doing what everyone else was doing, and how they dealt with worldwide environmental change made their population and probably other endemic populations disappear."

To see how ancient groups of people moved around as the climate changed, Barton and colleagues analyzed stone tools from 167 cave sites that spanned Eurasia from the Near East to Gibraltar. Fossils indicated whether Neanderthals, early humans or both had lived in each cave for some period of time between about 128,000 and 11,500 years ago.

As they scanned the tools, the major clue the researchers looked for was how worn down the stones were. That, in turn, hinted at how much moving around their owners did.

If people stayed put, for example, they tended to stockpile rocks and just chip off new flakes whenever they needed one. If they were moving around a lot, on the other hand, they carried tools with them, and they ended up sharpening and re-sharpening those tools over and over – ultimately leading to duller, more worn tools. In the fossil record, the difference between the two tool-making strategies is clear.

When the researchers analyzed the tools, they found that climate determined the migration patterns of both early humans and Neanderthals. When it was warm and resources were abundant but patchy, well-worn tools suggested that everyone moved around from place to place. They didn't roam very far, so they wouldn't have had a lot of contact with each other, but they didn’t stay in one place for a long time, either.

But when temperatures plummeted as a new glacial period approached, both Neanderthals and our human ancestors set up home bases where they could keep flaking off sharp new tools. From there, foraging parties covered much longer distances. As they roamed, the two groups intermingled more than they had ever had before

Because humans outnumbered Neanderthals, computer modeling over 1,500 generations showed that intermingling would have led to the eventual disappearance of a distinct Neanderthal group, whereas the smaller-scale movements seen in warmer times wouldn’t have had much of an effect at all.

Neanderthals didn't exactly go extinct, the researchers reported in the journal Human Ecology. Instead, Barton said, their genes were essentially swallowed up into the human genome.

Studies have shown similar patterns of extinction in endangered animal species, Barton said. And he pointed to recent evidence that remnants of Neanderthal DNA still persist in modern Europeans.

Neanderthals were certainly intelligent enough to adapt to climate change, said Richard Klein, an anthropologist at Stanford University in Palo Alto, Calif. But he is more skeptical about the conclusion that mating between Neanderthals and early humans was widespread enough to lead to Neanderthal extinction.

Read more at Discovery News

North Pole Dinosaurs Lived Short, Hard Lives

The winter holiday season often portrays the North Pole as a cozy fantasyland, but new research on dinosaurs that lived there shows that Arctic life has been tough for millions of years, with North Pole dinos finding it hard to reach their 20th birthday.

The findings, published in the journal Historical Biology, offer a rare look at dinosaur life stages. Fossils from high latitudes better express growth bands that reveal how these animals grew up. Scientists can then analyze them similar to how they study tree rings.

"We determine growth rates by looking at the number and spacing of the growth bands in a cross section of a femur," co-author Patrick Druckenmiller explained to Discovery News. "We measure the distance of each band from the center of the bone as a proxy for body size. In this case, it's presented as a percentage of total length. Growth banding becomes narrower as the growth rate progressively tapers off later in life."

Following this process, the researchers determined some polar dinosaurs grew rapidly as juveniles, became sexually mature at about age 9, and died at around age 19 (assuming they didn’t bite the dust due to disease, an accident, or for some other reason).

Druckenmiller, curator of Earth Sciences at the University of Alaska Museum, and colleague Gregory Erickson focused their research on Pachyrhinosaurus femur bones excavated from the early Maastrichian (about 65 to 70 million years ago) of Prince Creek Formation in Northern Alaska.

“Pachyrhinosaurus is a member of the horned dinosaur family Ceratopsidae,” Druckenmiller said. "It was a large, probably gregarious, herbivore. Instead of having thick horns over the eyes and nose area (think of the iconic Triceratops) it had large 'bosses,' which are bony growths that give the skull a very thick appearance."

This explain the dinosaur's name: Pachy, meaning "thick and heavy," and rhino, meaning "nose."

This dinosaur was far from being alone in the Arctic, however. The North Slope of Alaska was home to numerous other plant-eating and carnivorous dinosaurs. The most common was a duck-billed dino very similar to Edmontosaurus. The region was also home to a large tyrannosaurid, a few dromaeosaurs, and the human-sized Troodon.

Pachyrhinosaurus would have been preyed upon by the carnivores, but because of its size -- about 26 feet long and weighing around 4 tons -- Druckenmiller suspects few hunters "took on an adult-sized healthy animal."

Animals that would be expected from this area, such as lizards, crocodilians and turtles, have never been found. One reason could be that they had trouble getting to Alaska.

Hendrik Poinar, a McMaster University anthropologist who has also studied North Pole animals, told Discovery News that the Bering Land Bridge, which joined Alaska to eastern Siberia, may have been more of a barrier than a gateway.

Read more at Discovery News

Faster-Than-Light Neutrinos Re-Tested: Same Result

A fiercely contested experiment that appears to show the accepted speed limit of the Universe can be broken has yielded the same results in a re-run, European physicists said.

But counterparts in the United States said the experiment still did not resolve doubts and the Europeans themselves acknowledged this was not the end of the story.

On Sept. 23, the European team issued a massive challenge to fundamental physics by saying they had measured particles called neutrinos which traveled around six kilometers (3.75 miles) per second faster than the speed of light, determined by Einstein to be the highest velocity possible.

The neutrinos had been measured along a 732-kilometer (454-mile) trajectory between the European Center for Nuclear Research (CERN) in Switzerland and a laboratory in Italy.

The scientists at CERN and the Gran Sasso Laboratory in Italy scrutinized the results of the so-called OPERA experiment for nearly six months before cautiously making the announcement.

In October, responding to criticism that they had been tricked by a statistical quirk, the team decided they would carry out a second series of experiments.

This time, the scientists altered the structure of the proton beam, a factor that critics said could have affected the outcome.

The modification helped the team identify individual particles when they were fired out and when they arrived at their destination.

The new tests "confirm so far the previous results," the Italian Institute for Nuclear Physics (INFN) said in a press release.

"A measurement so delicate and carrying a profound implication on physics requires an extraordinary level of scrutiny," the INFN's president, Fernando Ferroni, said.

"The experiment OPERA, thanks to a specially adapted CERN beam, has made an important test of consistency of its result. The positive outcome of the test makes us more confident in the result, although a final word can only be said by analogous measurements performed elsewhere in the world".

In France, Jacques Martino, head of the National Institute of Nuclear and Particle Physics at the National Center of Scientific Research (CNRS), said "the search is not over."

"There are more checks of systematics currently under discussion, one of them could be a synchronization of the time reference at CERN and Gran Sasso independently from the GPS (Global Positioning System), using possibly a fiber."

A paper describing the re-run is published on Friday in the open-access Internet science journal, ArXiv.

In the United States, the famous US particle physics laboratory, Fermilab, said the experiment still failed to resolve questions as to whether the flight of the neutrinos had been accurately timed. Just the tiniest error would skew the whole findings.

Read more at Discovery News

Earth's Biggest Doomsday Event: Death By CO2

Earth's biggest mass extinction rolled over the planet like hell on wheels.

For the first time, paleontologists have pinned down exactly when and how fast the granddaddy of all mass extinctions took place, and their findings leave the finger of blame pointing squarely at a colossal and long-lived injection of carbon dioxide into the atmosphere. Sound familiar?

That ancient carbon dioxide came not from cars and factories, of course, but from massive volcanic eruptions, brush fires, and possibly even the combustion of coal seams ignited by hot lava.

The greenhouse gas increase, in turn, raised global temperatures and turned the oceans acidic and oxygen-deprived, among other trying consequences. Needless to say, life did not fare well. An oft-quoted estimate suggests that 90 percent of all marine life went extinct.

The new study, published this week in Science, puts that stark statistic into a fresh, rigorous perspective: At the peak of the crisis, right around 252.28 million years ago, and for at least 20,000 years, the planet was losing 3 percent of species every millennium.

“If we had continued losing at that rate for another 20,000 years, we wouldn’t be here to talk about it,” paleontologist Charles Henderson of the University of Calgary in Alberta, Canada, told Discovery News.

Henderson is among an international team of scientists, led by Shu-zhong Shen of the Nanjing Institute of Geology and Palaeontology in China, who compiled an intensive calibration of this most extreme of all biological crises, known to scientists as the end-Permian extinction, which occurred millions of years before the cosmic collisions that may have paved the way for dinosaurs.

For years the standard summary for the end-Permian extinction has been that 90 percent of life on earth was wiped out. But that number was just a statistical extrapolation. No study had ever considered more than a handful of samples at a time, Henderson explains.

This new study took into account the changes and disappearances of a total of 1,485 species, including shellfish, eel-like creatures called conodonts (see conondont teeth in the photo below) and various animals living on land. The team also took advantage of great improvements of dating techniques to determine absolute ages of the fossils.

A major conclusion of the study is that terrestrial and marine extinctions happened at the same time, a conclusion that has been controversial until recently.

Read more at Discovery News

Nov 17, 2011

World's Lightest Material Is a Metal 100 Times Lighter Than Styrofoam

A team of researchers from UC Irvine, HRL Laboratories and the California Institute of Technology have developed the world's lightest material -- with a density of 0.9 mg/cc -- about one hundred times lighter than Styrofoam™.

Their findings appear in the Nov. 18 issue of Science.

The new material redefines the limits of lightweight materials because of its unique "micro-lattice" cellular architecture. The researchers were able to make a material that consists of 99.99 percent air by designing the 0.01 percent solid at the nanometer, micron and millimeter scales. "The trick is to fabricate a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair," said lead author Dr. Tobias Schaedler of HRL.

The material's architecture allows unprecedented mechanical behavior for a metal, including complete recovery from compression exceeding 50 percent strain and extraordinarily high energy absorption.

"Materials actually get stronger as the dimensions are reduced to the nanoscale," explained UCI mechanical and aerospace engineer Lorenzo Valdevit, UCI's principal investigator on the project. "Combine this with the possibility of tailoring the architecture of the micro-lattice and you have a unique cellular material."

Developed for the Defense Advanced Research Projects Agency, the novel material could be used for battery electrodes and acoustic, vibration or shock energy absorption.

Read more at Science Daily

Asteroid Fingered For Dino Era Boom - Not Just Bust

Both the dinosaurs' rise and demise may have been caused by an out of this world phenomenon.

An asteroid impact on Mexico's Yucatan Peninsula is now widely believed to be the main event that sent the dinos to their doom. Now an impact crater in France is getting the honor of giving the “terrible lizards” their chance to take over the Triassic.

Paul Olsen and Dennis Kent of Columbia University's Lamont-Doherty Earth Observatory have been struck by the Triassic asteroid hypothesis for years, reported the journal Nature. But they didn't have proof. There was no smoking gun like the Chicxulub crater in the Yucatan.

What they were missing was evidence of what caused the wave of extinctions between the Triassic and Jurassic when, approximately 200 million years ago, many of the animals that shared the Earth with early dinosaurs disappeared within a few thousand years.

With mammal-like therapsids, crocodile-style archosaurs, and other beasts mostly out of the way, dinos rose to dominate life on Earth for the next 135 million years.

Earlier ideas about what may have caused this die-off related to the break-up of the super-continent Pangaea. Any heart-broken soul will tell you that a nasty break-up can feel like the end of the world, but the break-up of Pangaea puts that in perspective. Massive volcanoes spewed lava, ash and greenhouse gases as the continents tore apart.

Such a massive disruption may have been enough to cause extinctions, but the eruptions occurred over hundreds of thousands of years. The Triassic-Jurassic extinction took only a few thousand.

“The only thing anyone can say with any certainty about the Triassic–Jurassic mass extinction is that it happened,” Olsen told Nature. “Whatever it was that caused it, it happened so swiftly that most life forms never had time to adapt and evolve to meet the changes.”

But a possible clue lies in Europe.

An asteroid impact site near Rochechouart, France was re-dated last year to 199 million to 203 million years ago, perfect timing to coincide with the Triassic-Jurassic extinctions. Other evidence of an asteroid strike at the time of the extinction include a layer of grainy material in the geologic record oriented as if it came from the area of Rochechouart, Olsen told Nature.

Though the French crater is likely too small to have caused the extinctions by itself, it may have had accomplices. Other small asteroids could have struck at the same time. Or the impact may been the final straw that pushed a ecosystems already stressed by volcanic eruptions over the brink.

Read more at Discovery News

Divers Find the Wreck of 17th Century Warship

Swedish divers have discovered the wreck of one of the largest 17th century warships.

Found off the coast of the Baltic island of Öland at a depth of between 160 and 320 feet, the wooden wreck is believed to be that of the royal warship Svärdet.

According to Deep Sea Productions, the underwater research team who identified the wreck, the vessel is "a prime example of richly decorated 'gaudy' ships, built largely to impress the enemy."

The 82-foot Svärdet (the Sword) sank in 1676 in the largest naval battle in the Baltic, when Sweden was defeated by a Danish-Dutch fleet.

After fighting for five hours, the Svärdet was set afire by a Dutch ship.

"The commander, admiral Claes Uggla, chose to go under with his ship, rather than surrender to the enemy," Deep Sea Productions said in a statement.

The Svärdet went down with its sister ship the Kronan (the Crown), whose wreck was discovered in 1981. It has yielded more than 30,000 archaeological artifacts, many of which are displayed at the Kalmar County Museum in Sweden.

Resting on the bottom of the sea, the Svärdet boasts "important portions still intact, huge guns still protruding from the gun-ports," Deep Sea Productions said.

Indeed, the Baltic Sea lacks the shipworm that destroys woodenwrecks in saltier oceans.

Little doubt remains about the vessel's identity.

According to the researchers, wood from the wreck indicates it dates from the 17th century. Moreover, the fact that the stern of the ship is missing, is consistent with historical reports of explosions at the stern.

A few months ago, another team of divers discovered the 16th century warship Mars at a nearby location.

Built in 1561 for the first Swedish hereditary king, Erik XIV, the 230 feet Mars was the largest ship in the Baltic Sea.

Weighing about 1000 tons, equipped with more than 150 guns and cannon, she had more firepower than any warship before her.

Read more at Discovery News

First Teeth Grew on Outside of Body

The fictional Cheshire cat's smile seemed to have a life of its own, outside of the cat's body, and now new research suggests the world's first teeth grew outside of the mouth before later moving into the oral cavity.

The study, published in the Journal of Vertebrate Paleontology, supports what is known as the "outside-in" hypothesis of tooth evolution. The first teeth and smile, however, did not belong to a cat, but likely were flashed by small and spiny shark-like fishes.

That initial smile would have looked rather sinister.

"The first smile would probably have been a prickly one, with many tiny teeth that looked like pointy cheek scales, and other small tooth-like scales wrapping around the lips onto the outside of the head," co-author Mark Wilson told Discovery News.

For the study, Wilson, a professor in the Department of Biological Sciences at the University of Alberta, and his colleagues studied animals called ischnacanthid acanthodians, an extinct group of fish that resembled sharks. They lived during the Early Devonian period, which lasted from 416 to 397 million years ago.

The researchers determined that head scales from these fish were in transition, evolving from scales to teeth. The pointy structures were identified on the lips of the fish. This discovery helps to negate the “inside out” theory of tooth evolution, which holds that the first teeth emerged from structures in the pharynx progressing into the mouth.

Project leader Stephanie Blais, a University of Alberta researcher, told Discovery News that "our findings support the idea that teeth evolved from modified pointed scales on the mouth margins (lips) as we see in Obtusacanthus," one of the prehistoric fish included in the study. All of the analyzed fish specimens were excavated at the Man on the Hill site in the Mackenzie Mountains of Canada.

As to why teeth first evolved, Blais said they "would have conferred a major advantage in terms of food acquisition. Pointed scales near the margins of their mouths would have helped them grasp prey and hang on to it until they could swallow it whole."

Such prey consisted of "probably whatever they could swallow," co-author Lindsay MacKenzie of the University of Montana’s Department of Geosciences told Discovery News. Based on fossilized stomach contents and other evidence, their primary prey probably consisted of arthropods, including crustaceans, as well as a variety of soft-bodied creatures and fish.

Blais said jaws, which must have evolved earlier, and the tooth-like formations "allowed fishes to change from a filter-feeding or mud-grubbing more passive lifestyle to one of active predation."

The world's first aggressive conflicts also may have arisen at this point, since the move from passive feeding to hunting led to what Blais termed "the very first evolutionary arms race" among vertebrates, with some becoming predators and others becoming prey.

Read more at Discovery News

Nov 16, 2011

Origins of Antarctica's Ice-Covered Mountains Unraveled

Buried below more than a mile of ice, Antarctica's Gamburtsev Mountains have baffled scientists since their discovery in 1958. How did the mountains get there, and what role did they play in the spread of glaciers over the continent 30 million years ago? In the latest study on the mountains, scientists in the journal Nature say they have pieced together the puzzle of the origins and evolution of this mysterious mountain chain.

An international team of scientists flew over Antarctica's deep interior in 2008-2009 with ice-penetrating radar, gravity meters and magnetometers to reveal the peaks and valleys hidden below the ice. The data they gathered has provided insight into how the mountains arose. One billion years ago, before animals or plants appeared on land, several continents collided and the oldest rocks that make up the Gamburtsevs smashed together. From the collision, a thick crustal root formed deep beneath the mountain range. Over time, these ancient mountains were eroded but the cold dense root remained.

Between 250 and 100 million years ago -- when dinosaurs walked Earth -- the supercontinent Gondwana, which included Antarctica, ripped apart, causing the old crustal root to warm. Reactivated, the crustal root and the East Antarctic Rift pushed land upwards again, reforming the mountains. Rivers and glaciers carved deep valleys and raised peaks to create a spectacular landscape that resembled the European Alps. The East Antarctic Ice Sheet, which formed 34 million years ago and at 10 million square kilometers covers an area the size of Canada, protected the mountains from erosion.

"It has been almost a billion years since the Gamburtsev first formed," said study co-author Robin Bell, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory. "This work shows that very old mountains can rise again, like a Phoenix from the ashes. The Gamburtsevs rose from the long eroded East Antarctic craton."

The study also resolves an apparent contradiction: how could such ancient mountains have retained their tall, jagged, and youthful peaks, said study co-author Carol Finn, a scientist at the U.S. Geological Survey. "We are accustomed to thinking that mountain building relates to a single tectonic event, rather than sequences of events," she said. "The lesson we learned about multiple events forming the Gamburtsevs may inform studies of the history of other mountain belts."

"It was fascinating to find that the East Antarctic rift system resembles one of the geological wonders of the world -- the East African rift system -- and that it provides the missing piece of the puzzle that helps explain the Gamburtsev Subglacial Mountains," said study lead author Fausto Ferraccioli, a scientist at British Antarctic Survey. "The rift system was also found to contain the largest subglacial lakes in Antarctica."

The team's next goal is to drill through the ice and collect the first Gamburtsev rock samples. "Amazingly, we have samples of the moon but none of the Gamburtsevs," said Bell. "With these rock samples we will be able to constrain when this ancient piece of crust was rejuvenated and grew to a magnificent mountain range."

The work was funded by grants from the U.S. National Science Foundation (NSF) and was launched in conjunction with the International Polar Year, an effort to study the Arctic and Antarctic spanning 2007-2009 and involving research by thousands of scientists from more than 60 nations. "It is very fitting that the initial results of Antarctica's Gamburtsev Province project are coming out 100 years after the great explorers raced to the South Pole," said Alexandra Isern, program director at NSF. "The scientific explorers of the AGAP project worked in harsh conditions to collect the data and detailed images of this major mountain range under the East Antarctic Ice Sheet. The results of their work will guide research in this region for many years to come."

Read more at Science Daily

Nest Full of Baby Dinosaurs Found

A 70-million-year-old nest of the dinosaur Protoceratops andrewsi has been found with evidence that 15 juveniles were once inside it, according to a paper in the latest Journal of Paleontology.

While large numbers of eggs have been associated with other dinosaurs, such as the meat-eating Oviraptor or certain duck-billed hadrosaurs, finding multiple juveniles in the same dino nest is quite rare.

"I, for one, cannot think of another dinosaur specimen that preserves 15 juveniles at its nest in this way," lead author David Fastovsky told Discovery News.

Fastovsky, who is chair of the University of Rhode Island’s Department of Geosciences, and his colleagues analyzed the dinosaur remains along with the nest, which measured about 2.3 feet in diameter and was round and bowl-shaped. All were found at Djadochta Formation, Tugrikinshire, Mongolia, where it's believed sand “rapidly overwhelmed and entombed” the youngsters while they were still alive.

The researchers conclude that the 15 dinosaurs all show juvenile characteristics. These include short snouts, proportionately large eyes, and an absence of adult characteristics, such as the prominent horns and large frills associated with adults of this species. At least 10 of the 15 fossil sets are complete.

The nest and its contents imply that Protoceratops juveniles remained and grew in their nest during at least the early stages of postnatal development. The nest further implies that parental care was provided.

The large number of offspring, however, also suggests that juvenile dinosaur mortality was high, not only from predation, but also from a potentially stressful environment.

"Large clutches may have been a way of ensuring survival of the animals in that setting -- even if there was extensive parental care," Fastovsky said. "Mongolia was, at the time, a place with a variety of theropod dinosaurs, some of whom likely ate babies such as these."

"The most obvious of these, found in the same deposits, is the (in)famous Velociraptor, a smallish nasty theropod with bad breath, for whom babies such as these would have made a nice bon bon," he continued.

Yet another discovery previously found at the same locality is the famous "fighting dinosaurs" specimen in which a Protoceratops and Velociraptor appear to have been preserved together "locked in what was evidently mortal combat," Fastovsky added. Parents and other adults of the sheep-sized herbivorous species may then have spent much of their time fighting off such hungry predators.

In a separate study, Lars Schmitz of the UC Davis Department of Evolution and Ecology, and colleagues studied bones surrounding what would have been the eyes of Protoceratops and other dinosaurs. The results allowed Schmitz and his team to conclude that this dinosaur and additional plant eaters were active both day and night. Velociraptor, on the other hand, was primarily a nocturnal carnivore, so night raids on Protoceratops nests must have taken place during the Late Cretaceous.

Even if the juvenile dinosaurs and their parents "had a good sensory system to notice a predator closing in, the success rate of a nocturnal attack may be higher than a diurnal attack," Schmitz told Discovery News.

Given the chances then of literally biting the (sand) dust or becoming dinner, it’s no wonder that some small dinosaurs had so many kids.

Read more at Discovery News

Serenity in the Milky Way

Some of the most beautiful sights in the universe are ones that we could never see with our eyes. One such example is this lovely composite of the Carina Nebula made with visible and radio light.

The visible light image is a wide-angle view of an active star forming region of our galaxy. This large complex of gas clouds can be seen from the Southern Hemisphere, but it is not as famous as its cousin, the Orion Nebula.

Over a year ago, astronomers using the Atacama Pathfinder EXperiment, or APEX, studied the parts of the nebula that are not visible to our eyes or to optical telescopes.

The orange "blobs" in this image represent the regions that glow as seen by a sub-millimeter telescope such as APEX. Most of this emission comes from dust which is warmed up by ultraviolet and visible light from the young stars that then radiates at longer wavelengths. Many of the young stars are extremely large, hot, and will not live for much longer in cosmic timescales.

However, not all of the gas in the nebula will actually form stars. Only about 10 percent of this gas is dense enough to start the star birth process, and this is pretty typical for our galaxy.

A small fraction of interstellar gas in the Milky Way is creating new stars at any given time while the rest is just... there. That may be a little stellar-centric of me to say, but as a living being on a planet, I am prejudiced towards environments that make planets.

The stuff of life itself may be in these clouds. Astronomers estimate that the cloud is 200,000 times the mass of our sun, and most of the material is in a molecular state. That means that the atoms are combining in ways similar to the chemistry that governs life on Earth. It's almost sad to think of all that raw material that orbits in our galaxy, perhaps never to be used to build a new star or planets.

Read more at Discovery News

Life-Bearing Lake Possible on Icy Jupiter Moon

New research shows the jumbled ice blocks crowning the surface of Jupiter's icy moon Europa are signs of a large liquid lake the volume of the North American Great Lakes just below the surface, a key finding in the search for places where life might exist beyond Earth.

Drawing from studies of underground volcanoes in Iceland and Antarctica, scientists ran computer models to see if the chaotic formations on Europa's surface could be explained by the same geologic processes seen on Earth.

"We looked at melt underneath the ice and the fracture and collapse of ice shelves," Britney Schmidt, a postdoctoral fellow at the University of Texas at Austin's Institute for Geophysics, told Discovery News.

"We come with these large pockets of water that form lakes. As they melt they actually break up the ice above it, like what you see on Earth," she said.

"This is certainly the best model so far," Paul Schenk, a staff scientist with the Lunar and Planetary Institute in Houston, wrote in an email to Discovery News. "If we go back with penetrating radar instruments we should be able to see into the ice shell, determine the stratigraphy of the layers in the shell and verify which models works best."

Europa, which is slightly smaller than Earth's moon, is believed to have a large ocean of salty water deep beneath its frozen crust. These recently discovered lakes appear to be embedded closer to the surface.

"Europa has more water than all of Earth's oceans," planetary scientist Simon Kattenhorn, with the University of Idaho, told Discovery News.

While the ocean itself is of interest to scientists searching for life beyond Earth, a mechanism to churn the surface ice and subsurface water makes Europa an even more compelling target.

Read more at Discovery News

Nov 15, 2011

Leonardo’s Formula Explains Why Trees Don’t Splinter

The graceful taper of a tree trunk into branches, boughs, and twigs is so familiar that few people notice what Leonardo da Vinci observed: A tree almost always grows so that the total thickness of the branches at a particular height is equal to the thickness of the trunk. Until now, no one has been able to explain why trees obey this rule. But a new study may have the answer.

Leonardo’s rule holds true for almost all species of trees, and graphic artists routinely use it to create realistic computer-generated trees. The rule says that when a tree’s trunk splits into two branches, the total cross section of those secondary branches will equal the cross section of the trunk. If those two branches in turn each split into two branches, the area of the cross sections of the four additional branches together will equal the area of the cross section of the trunk. And so on.

Expressed mathematically, Leonardo’s rule says that if a branch with diameter (D) splits into an arbitrary number (n) of secondary branches of diameters (d1, d2, et cetera), the sum of the secondary branches’ diameters squared equals the square of the original branch’s diameter. Or, in formula terms: D2 = ∑di2, where i = 1, 2, … n. For real trees, the exponent in the equation that describes Leonardo’s hypothesis is not always equal to 2 but rather varies between 1.8 and 2.3 depending on the geometry of the specific species of tree. But the general equation is still pretty close and holds for almost all trees.

Botanists have hypothesized that Leonardo’s observation has something to do with how a tree pumps water from its roots to leaves. The idea being that the tree needs the same total vein diameter from top to bottom to properly irrigate the leaves.

But this didn’t sound right to Christophe Eloy, a visiting physicist at the University of California, San Diego, who is also affiliated with University of Provence in France. Eloy, a specialist in fluid mechanics, agreed that the equation had something to do with a tree’s leaves, not in how they took up water, and the force of the wind caught by the leaves as it blew.

Eloy used some insightful mathematics to find the wind-force connection. He modeled a tree as cantilevered beams assembled to form a fractal network. A cantilevered beam is anchored at only one end; a fractal is a shape that can be split into parts, each of which is a smaller, though sometimes not exact, copy of the larger structure. For Eloy’s model, this meant that every time a larger branch split into smaller branches, it split into the same number of branches, at approximately the same angles and orientations. Most natural trees grow in a fairly fractal fashion.

Because the leaves on a tree branch all grow at the same end of the branch, Eloy modeled the force of wind blowing on a tree’s leaves as a force pressing on the unanchored end of a cantilevered beam. When he plugged that wind-force equation into his model and assumed that the probability of a branch breaking due to wind stress is constant, he came up with Leonardo’s rule. He then tested it with a numerical computer simulation that comes at the problem from a different direction, calculating forces on branches and then using those forces to figure out how thick the branches must be to resist breakage (see illustration). The numerical simulation accurately predicts the branch diameters and the 1.8-to-2.3 range of Leonardo’s exponent, Eloy reveals in a paper soon to be published in Physical Review Letters.

“Trees are very diverse organisms, and Christophe seems to have arrived at a simple and elegant physical principle that explains how branches taper in size as you go from the trunk, through the boughs, up to the twigs,” says Marcus Roper, a mathematician at UC Berkeley. “It’s surprising and wonderful that no one thought of [the wind explanation] sooner.”

Read more at Wired Science

First Arabic Crusader Inscription Found

Israeli archaeologists have discovered the first ever Arabic Crusader inscription, they announced on Monday.

The epigraphic evidence emerged from a 800-year-old inscribed marble slab which originally sat in Jaffa's city wall.

Bearing the name of the "Holy Roman Emperor" Frederick II, and the date "1229 of the Incarnation of our Lord Jesus the Messiah," the inscription was found broken on the top, right, left and bottom.

"The script is peculiar but once the slab was reassembled, it was deciphered with little effort," Moshe Sharon, of Hebrew University, told Discovery News.

According to Sharon and colleague Ami Shrager, the inscription was drafted by Frederick's officials, or possibly even the emperor himself, who was fluent in Arabic.

"Muslim scholars attended Frederick's court in Sicily, where his main royal palace was located. There, he also had a harem that included a Muslim concubine," Sharon said.

The grandson of both Frederick Barbarossa and Roger II of Sicily, Frederick II (1194- 1250) was the Christian king who led the Sixth Crusade of 1228-1229.

A series of military campaigns launched by the Christian countries of western Europe, the Crusades spanned two centuries, from 1095 to 1291.

Wearing a large Christian cross embroidered on their armor and shields, tens of thousands of men fought the Muslims to restore Christian control in and near Jerusalem.

"Frederick succeeded, without resorting to arms, in achieving major territorial gains for the Crusader Kingdom," Sharon said.

The emperor's most important feat was the handing over of Jerusalem to the Crusaders by the Egyptian sultan al-Malik al-Kamil, who had been impressed with Frederick's knowledge of Arabic language.

Prior to achieving this agreement in 1229, the emperor, who had been excommunicated by Pope Gregory IX for not starting the Crusade earlier, fortified the castle of Jaffa and left in its walls two inscriptions, one in Latin and the other in Arabic.

Only a small fragment remains of the Latin inscription. It was studied in the 19th century by the French Orientalist and archaeologist Clermont-Ganneau who ascribed it to Frederick II.

The Arabic inscription lists all the titles of Frederick and the Italian provinces he ruled. It also stresses that Frederick is the Holy Roman Emperor, "the protector of the Pope in Rome" and the "King of Jerusalem" -- a crown "he put on his own head in the Church of the Holy Sepulcher in Jerusalem, and which he had assumed after marrying the 12 years old Yolanda the Queen of Jerusalem in 1225," Sharon said.

Read more at Discovery News

Psychedelic-Colored Insects Flew Ancient Skies

At least one moth 50 million years ago sported a yellow-green hue highlighted by blue, black and green-cyan accents, a team of researchers concludes.

The fashion forward moth, described in the latest PLoS Biology, represents the oldest known moth for which the original colors have been determined.

The discovery, made in Germany, could help scientists learn the colors of a wide variety of long-extinct creatures, including birds, fishes, and other insects, and shed light on color's function and evolution.

"We can work out what they looked like and what they used the colors for," Yale researcher Maria McNamara said in a press release.

Fossils rarely preserve evidence of original color, so we've only known the Dinosaur Era and other prehistoric times in black and white, although artists have taken creative liberties in adding color to drawings.

McNamara and her team, however, have figured out a way to tease color information out of fossils. Coloration, in turn, suggests how the long-dead individuals may have behaved and communicated, since color can play a role in both of those things.

The scientists figured out the colors by using electron microscopy and other techniques to examine fossilized scales of daytime moths that lived around 50 million years ago. The moths lived at what is now the Messel oil shale pit near Frankfurt, where numerous other high-quality fossils have been unearthed.

Evidence from anatomical details preserved in the scales helped establish the structural color of the moths' forewings, which you can see in the recreation image. McNamara says that structural colors are the brightest colors in nature -- purer and more intense than chemical pigments. Tissue design generates structural colors by scattering light.

The researchers believe the ancient day moth's colors served defensive purposes by either warning off predators, or serving as camoflauge.

Read more at Discovery News

Sweet Spot for Life's Chemistry Discovered

When scientists realized early Earth didn't have the right ingredients for life on its own, they started looking in space for the complex organic molecules needed to get things going.

Of particular interest is methanol, which can trigger the more complex chemistry that leads to amino acids, the building blocks for proteins and life.

"Methanol is the most complex molecule you can form at the really low temperatures in interstellar space," astronomer Douglas Whittet, with Rensselaer Polytechnic Institute, told Discovery News. "When you put methanol into a newly forming star system, you have some heat from a proto-sun and that's when methanol really takes off. It's the springboard for more exciting chemistry that follows."

In other words, find the methanol and scientists believe you find the chemical pathways to life.

"Searching for methanol in various regions in space will tell researchers where to look for other complex organic molecules, which will eventually lead to the formation of life," astronomer Sachindev Shenoy, with NASA's Ames Research Center in California, told Discovery News.

But where to look?

A new analysis by Whittet and colleagues shows there is a "sweet spot" around a few young stars where methanol production is cranking. What seems to be key is how fast molecules can reach dust grains, which serve as a scaffolding of sorts for chemical reactions.

"The rate of molecule accumulation on the particles can result in an organic boom or a literal dead end," Whittet said.

Not all young stars are suited for organic chemistry. Whittet's team found a range of methanol concentrations in clouds from practically zero to about 30 percent.

If molecules build up too quickly on the surfaces of dust grains, there's not enough time for chemical reactions to occur before they are buried by other molecules. If the buildup is too slow, there are fewer chances for chemical reactions.

The research has implications for understanding where to look for life and suggests it may be more plentiful, from a chemistry point of view, than previously thought.

Read more at Discovery News

Nov 14, 2011

Archeologists Discover a Huge Ancient Greek Commercial Area On Island of Sicily

Led by Professor Dr. Martin Bentz, Bonn archeologists began unearthing one of Greek antiquity's largest craftsmen's quarters in the Greek colonial city of Selinunte (7th-3rd century B.C.) on the island of Sicily during two excavation campaigns in September 2010 and in the fall of 2011.

The project is conducted in collaboration with the Italian authorities and the German Archaeological Institute. Its goal is to study an area of daily life in ancient cities that has hitherto received little attention.

"To what extent the ancient Greeks already had something like "commercial areas" has been a point of discussion in expert circles to this day," said Bonn archeologist Dr. Gabriel Zuchtriegel, a research associate who coordinates the Selinunte project together with Dr. Jon Albers from the Institut für Klassische Archäologie der Universität Bonn at the Chair of Prof. Dr. Martin Bentz. " A concentration of certain 'industries' and craftsmen in special districts does not only presuppose proactive planning; it is also based on a certain idea of how a city should best be organized -- from a practical as well as from a social and political point of view, e.g., who will be allowed to live and work where?" The University of Bonn excavations are now contributing to finding a new answer to such questions.

Huge kilns, used communally

Concentration in a certain city district applied primarily to potteries in Selinunte, which were massed on the edge of the settlement in the very shadow of the city wall. "Consequently, their smoke, stench and noise did not inconvenience the other inhabitants as much," explained Dr. Zuchtriegel. "At the same time, this allowed several craftsmen to use kilns and storage facilities together." The excavations showed that the potters joined cooperatives that shared in the use of gigantic kilns with a diameter of up to 7 meters. The craftsmen's district in Selinunte probably stretched for more than 600 meters along the city walls and is thus among the largest ones known today. The excavations are in the hands of faculty and students from Bonn and Rome -- and they are exhausting. For excavations go on in August and September, when the heat reaches its peak -- but in exchange, there is very little rain.

"This work is a challenge for all involved," commented dig manager Bentz. "This is no camping trip." But for students, it is a great opportunity to learn archeological methods by doing. The Bonn researchers were surprised to find even older remnants of workshops under the 5th c. kilns. While these finds have not been completely excavated yet, indications are -- so the archeologists -- that pottery workshops existed in the same location during the city's early phase in the 6th century B.C. This means that craftsmen were probably intentionally housed on the edge as early as during the design of the city, which was -- like many colonies -- planned on the drawing board.

Read more at Science Daily

Ancient Bronze Artifact from East Asia Unearthed at Alaska Archaeology Site

A team of researchers led by the University of Colorado Boulder has discovered the first prehistoric bronze artifact made from a cast ever found in Alaska, a small, buckle-like object found in an ancient Eskimo dwelling and which likely originated in East Asia.

The artifact consists of two parts -- a rectangular bar, connected to an apparently broken circular ring, said CU-Boulder Research Associate John Hoffecker, who is leading the excavation project. The object, about 2 inches by 1 inch and less than 1 inch thick, was found in August by a team excavating a roughly 1,000-year-old house that had been dug into the side of a beach ridge by early Inupiat Eskimos at Cape Espenberg on the Seward Peninsula, which lies within the Bering Land Bridge National Preserve.

Both sections of the artifact are beveled on one side and concave on the other side, indicating it was manufactured in a mold, said Hoffecker, a fellow at CU-Boulder's Institute of Arctic and Alpine Research. A small piece of leather found wrapped around the rectangular bar by the research team yielded a radiocarbon date of roughly A.D. 600, which does not necessarily indicate the age of the object, he said.

"I was totally astonished," said Hoffecker. "The object appears to be older than the house we were excavating by at least a few hundred years."

Hoffecker and his CU-Boulder colleague Owen Mason said the bronze object resembles a belt buckle and may have been used as part of a harness or horse ornament prior to its arrival in Alaska. While they speculated the Inupiat Eskimos could have used the artifact as a clasp for human clothing or perhaps as part of a shaman's regalia, its function on both continents still remains a puzzle, they said.

Since bronze metallurgy from Alaska is unknown, the artifact likely was produced in East Asia and reflects long-distance trade from production centers in either Korea, China, Manchuria or southern Siberia, according to Mason. It conceivably could have been traded from the steppe region of southern Siberia, said Hoffecker, where people began casting bronze several thousand years ago.

Alternatively, some of the earliest Inupiat Eskimos in northwest Alaska -- the direct ancestors of modern Eskimos thought to have migrated into Alaska from adjacent Siberia some 1,500 years ago -- might have brought the object with them from the other side of the Bering Strait. "It was possibly valuable enough so that people hung onto it for generations, passing it down through families," said Mason, an INSTAAR affiliate and co-investigator on the Cape Espenberg excavations.

The Seward Peninsula is a prominent, arrowhead-shaped land mass that abuts the Bering Strait separating Alaska from Siberia. The peninsula was part of the Bering Land Bridge linking Asia and North America during the last ice age when sea level had dropped dramatically, and may have been used by early peoples as a corridor to migrate from Asia into the New World some 14,000 years ago.

The artifact was discovered in August by University of California, Davis, doctoral student Jeremy Foin under 3 feet of sediment near an entryway to a house at Cape Espenberg. Other project members included Chris Darwent of UC Davis, Claire Alix of the University of Paris, Nancy Bigelow of the University of Alaska Fairbanks, Max Friesen of the University of Toronto and Gina Hernandez of the National Park Service.

"The shape of the object immediately caught my eye," said Foin, who spotted the soil-covered artifact in an archaeological sifting screen. "After I saw that it clearly had been cast in a mold, my first thought was disbelief, quickly followed by the realization that I had found something of potentially great significance."

The CU-led excavations are part of a National Science Foundation-funded project designed to study human response to climate change at Cape Espenberg from A.D. 800 to A.D. 1400, a critical period of cultural change in the western Arctic, said Mason. Of particular interest are temperature and environmental changes that may be related to Earth's Medieval Warm Period that lasted from about A.D. 950 to 1250.

"That particular time period is thought by some to be an analog of what is happening to our environment now as Earth's temperatures are rising," said Mason. "One of our goals is to find out how these people adapted to a changing climate through their subsistence activities."

The Cape Espenberg beach ridges, wave-swept deposits made of sand and sediment running parallel to the shoreline that were deposited over centuries, often are capped by blowing sand to form high dunes. The Cape Espenberg dwellings were dug into the dunes and shored up with driftwood and occasional whale bones.

The team is examining the timing and formation of the beach ridges as well as the contents of peat and pond sediment cores to help them reconstruct the sea-level history and the changing environment faced by Cape Espenberg's settlers. Information on past climates also is contained in driftwood tree rings, and the team is working with INSTAAR affiliate Scott Elias, a University of London professor and expert on beetle fossils, who is helping the team reconstruct past temperatures at Cape Espenberg.

While the hunting of bowhead whales was a way of life for Inupiat Eskimos at Barrow and Point Hope in northwestern Alaska 1,000 years ago, it is still not clear if the Cape Espenberg people were whaling, said Mason. While whale baleen -- a strong, flexible material found in the mouths of whales that acts as a food filter -- and a variety of whale bones have been found during excavations there, the sea offshore is extremely shallow and some distance from modern whale migration routes. However, there is evidence of fishing and seal and caribou hunting by the group, he said.

The Inupiat Eskimos are believed to have occupied Cape Espenberg from about A.D. 1000 until the mid-1800s, said Hoffecker. They are part of the indigenous Eskimo culture that lives in Earth's circumpolar regions like Alaska, Siberia and Canada.

Read more at Science Daily

X-ray Laser to Recreate Conditions at Earth’s Core

The very center of the Earth has been described as the “last white spot” on our globe: a mysterious super-hot chamber that we know surprisingly little about. An X-ray beamline at the European Synchrotron Radiation Facility (ESRF) in France will, hopefully, unlock some of its secrets.

The inner core of our planet, hiding 2,500 kilometers beneath the surface, endures about three and a half million times atmospheric pressure and a temperature thought to be roughly as hot as the surface of the sun.

The X-ray beam, called ID24, attempts to reproduce some of those extreme conditions in the lab. Diamond anvil cells squeeze a material to intense pressures, and laser pulses heat it to unimaginable temperatures. The samples may be no bigger than a speck of dust and the heat may only be applied for microseconds, but it’s the closest approximation of the Earth’s center that we can get.

This will allow scientists in various fields to discover what happens when you heat iron to 10,000 degrees C, what happens when materials undergo a fast chemical reaction or at what temperature a mineral will melt in the interior of a planet. It will hopefully answer some burning questions that keep geologists up at night.

Cosmologists, too. That elusive “warm dense matter” may well live inside large planets like Jupiter, and we know even less about them. ID24 allows sample volumes 10,000 times smaller than those at the high power laser facilities to be studied, making such experiments possible.

Read more at Wired Science

First Stars May Not Have Been Monsters

Astronomers are seeking to explore a little-studied time in our universe's history known as "the Dark Ages." The universe was dark in that no galaxies shined brightly as we see today. Yet somehow, out of this dark, mostly-hydrogen gas, the very first stars did form somehow, lighting up the cosmos for the very first time.

What these first stars were like is still a debate amongst astronomers since there is a lack of direct observations.

Astronomers can simulate the formation of stars under the conditions that were present in the very early universe. However, the scenario is complex on large and small scales and involves many physical and chemical processes, all which need to be tracked carefully.

Often, some assumptions and approximations must be made in order for the simulation to fit into a realistic computational space and time.

Many previous models of the first stars were semi-analytic, meaning that some processes were approximated through the use of equations, rather than just letting the simulation progress in a purely numerical way. These have long predicted that, in the absence of heavier elements such as carbon, nitrogen, and oxygen, that the first stars would be truly massive, reaching hundreds of times the mass of the sun before finishing their growth.

Such behemoths would live out very short lives and explode catastrophically in a type of supernova that is not seen in the universe today; a "pair-instability" supernova.

This collapse and subsequent explosion is so violent that it does not leave a black hole remnant behind, as other large supernovae do. However, the pattern of elements created by such a supernova should be detectable in the gas left over, now trapped in old "metal-poor" stars wandering the galaxy. (Remember, in this case, astronomers refer to "metals" as any element that is not hydrogen and helium. Sorry, chemists.)

The problem with this hypothesis up until now is that the pattern of elements in old, metal-poor stars does not match this prediction. Instead, it looks as if the gas was created in "regular" core-collapse supernovae that we still see today that herald the death of a star that is tens of times the mass of our sun. This explosion leaves behind a neutron star or black hole as a remnant.

This new simulation of a star forming in the early universe explains why this might be the case. The group of astronomers, led by Takashi Hosokawa of the Jet Propulsion Laboratory (JPL) at NASA, used radiation hydrodynamical simulations to plot out the birth and life of this model star. This means they used principles of fluid flow mechanics and took into account the effects that the light of the star itself has on the process.

They found that the protostar formed a disk of material around it, as was expected, from which material flowed onto the star-to-be. As the star got denser and hotter, its radiation heated and ionized some of the gas around it, until the pressure was too great and gas began to flow out from the polar regions of the star. This outflow expanded until it cut off the gas falling on to the disk around the star, thus cutting off the star's food supply.

Finally, the disk itself was blasted away by the star's bright light, and 100,000 years after the star began to form, it had reached 35 times the mass of the sun and had begun nuclear fusion in its core.

35 solar masses is still pretty huge, though not the hundreds of solar masses that were expected. This type of star may have been more typical of the first stars, leading to core-collapse supernovae within a few million years. Though the existence of the super-behemoth stars has not been ruled out, the early chemical evolution of the universe was probably dominated more like this kind of star.

Read more at Discovery News

Nov 13, 2011

Fastest Stellar Spinner Will Die a Violent Death

The sun rotates at a respectable 2 kilometers per second, which may sound pretty fast. But according to a study to be published in The Astrophysical Journal Letters (arXiv:1111.0157v1), a star has been detected in 30 Doradus (a.k.a. the Tarantula Nebula in the Large Magellanic Cloud, 160,000 light-years away) spinning at the breakneck speed of 600 kilometers per second!

According to Ken Croswell at, if the star spun just 20 percent faster, centrifugal forces would rip the star to shreds. If an aircraft could travel this fast, it could fly from New York to Los Angeles in a little under 7 seconds!

We often hear of rapidly spinning compact objects, like pulsars -- spinning, X-ray-emitting neutron stars -- but rapidly spinning normal stars are very rare. In the case of VFTS 102, it's a real oddity and it's a record-breaker.

The young, blue, O-type star must have been sped up in some way. After all, stars spinning this fast aren't born naturally.

The international team of astronomers working on this study think they know why VFTS 102 is in such a mess. When looking around the star's neighborhood, they noted a pulsar speeding away from VFTS 102, as if running from the scene of a crime. They believe the pulsar may also be the victim of the event that caused VFTS 102's strange spin.

Once a binary pair -- two stars mutually orbiting each other -- one of the stars exploded as a supernova. As the supernova detonated, leaving the pulsar behind as a supernova remnant, the ejected gas was dumped onto VFTS 102. The rapid increase in mass caused the star to be "spun up."

As mass was lost in an instant from one of the stars as it exploded, the gravitational bond between the stars was lost, causing the pair to be flung away from each other, much like a hammer-thrower releasing a hammer. This is why both the pulsar and VFTS 102 are flying apart.

Read more at Discovery News