BREAKING NEWS: Magma Pancakes Beneath Lake Toba as Process of Mantle Plumes

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Where do the tremendous amounts of material that are ejected from huge volcanic calderas during super-eruptions actually originate?

The tremendous amounts of lava that are emitted during super-eruptions accumulate over millions of years prior to the event in the Earth’s crust. These…

Where do the tremendous amounts of material that are ejected from huge volcanic calderas during super-eruptions actually originate?

gloss_caldera_m

The tremendous amounts of lava that are emitted during super-eruptions accumulate over millions of years prior to the event in the Earth’s crust. These reservoirs consist of magma that intrudes into the crust in the form of numerous horizontally oriented sheets resting on top of each other like a pile of pancakes.

A team of geoscientists from Novosibirsk, Paris and Potsdam presents these results in the current issue of Science. The scientists investigate the question on where the tremendous amounts of material that are ejected from within huge calderas during super-eruptions actually originate.

LongValleyCaldera_m

Here we are not dealing with large volcanic eruptions of the size of Pinatubo of Mount St. Helens, here we are talking about extreme events: The Toba-caldera in the Sumatra subduction zone in Indonesia originated from one of the largest volcanic eruption in recent Earth history, about 74,000 years ago. It emitted the enormous amount of 2,800 cubic kilometers of volcanic material with a dramatic global impact on climate and environment. Hereby, the 80 km long Lake Toba was formed.

Geoscientists were interested in finding out: How can the gigantic amounts of eruptible material required to form such a super volcano accumulate in the Earth’s crust. Was this a singular event thousands of years ago or can it happen again?

ocean_bottom_magma_m

Researchers from the GFZ German Research Centre for Geosciences successfully installed a seismometer network in the Toba area to investigate these questions and provided the data to all participating scientists via the GEOFON data archive. GFZ scientist, Christoph Sens-Schönfelder, a co-author of the study explains: “With a new seismological method we were able to investigate the internal structure of the magma reservoir beneath the Toba-caldera. We found that the middle crust below the Toba supervolcano is horizontally layered.” The answer thus lies in the structure of the magma reservoir. Here, below 7 kilometers the crust consists of many, mostly horizontal, magmatic intrusions still containing molten material.

New seismological technique
It was already suspected that the large volume of magma ejected during the supervolcanic eruption had slowly accumulated over the last few millions of years in the form of consequently emplaced intrusions. This could now be confirmed with the results of field measurements. The GFZ scientists used a novel seismological method for this purpose. Over a six-month period they recorded the ambient seismic noise, the natural vibrations which usually are regarded as disturbing signals. With a statistical approach they analyzed the data and discovered that the velocity of seismic waves beneath Toba depends on the direction in which the waves shear the Earth’s crust. Above 7 kilometers depth the deposits of the last eruption formed a zone of low velocities. Below this depth the seismic anisotropy is caused by horizontally layered intrusions that structure the reservoir like a pile of pancakes. This is reflected in the seismic data.

Supervolcanoes
Not only in Indonesia, but also in other parts of the world there are such supervoclcanoes, which erupt only every couple of hundred thousand years but then in gigantic eruptions. Because of their size those volcanoes do not build up mountains but manifest themselves with their huge carter formed during the eruption – the caldera. Other known supervolcanoes include the area of the Yellow-Stone-Park, volcanoes in the Andes, and the caldera of Lake-Taupo in New Zealand. The present study helps to better understand the processes that lead to such super-eruptions.

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LOFAR Discovers Largest Carbon Atoms Outside Our Milky Way

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An international team of astronomers under the guidance of graduate student Leah Morabito of Leiden Observatory has for the first time discovered the largest carbon atoms outside our Milky Way with the LOFAR radio telescope. In the future astronomers will be able to measure how cold and dense…

An international team of astronomers under the guidance of graduate student Leah Morabito of Leiden Observatory has for the first time discovered the largest carbon atoms outside our Milky Way with the LOFAR radio telescope. In the future astronomers will be able to measure how cold and dense the gas around these atoms is that influences star formation and the evolution of a galaxy. The results are published in the journal Astrophysical Journal Letters on October 28th.

“Carbon atoms are about half a million times smaller than the average thickness of a human hair, but they can be a billion times larger in the cold and sparse gas. The outermost electron is then orbiting the nucleus at a much larger distance,” explains first author Morabito. The outermost electron can be captured by an atom that is missing an electron. A spectral line will then be visible in the light spectrum. All spectral lines form the chemical fingerprint of an atom such as carbon.

Astronomers predicted in the 70’s that the carbon spectral line would be detectable outside our galaxy. This first observation took 40 years to be made. The line is hard to detect because it is too faint when the gas that is surrounding the atoms is too warm or too dense. The cold, sparse gas is present in starburst galaxies—galaxies in which stars form at a high rate. For this reason the carbon spectral line is easier to detect in galaxies of this type.

Most radio telescopes observe at frequencies at which the carbon line can not be detected. Other telescopes are not sensitive enough to detect the spectral lines of the carbon atoms at low frequencies. The LOFAR radio telescope, that stretches from the northeast of the Netherlands across Europe, is perfect for these kind of observations because of its frequency range and sensitivity. Co-author Raymond Oonk from Leiden Observatory en ASTRON: “LOFAR is an unique telescope. This telescope opens up a new window on the universe.”

The carbon atoms are present in the heart of the starburst galaxy M82, where 10 times more stars are being born in the same period as in our Milky Way. The cold and sparse gas in this area impacts star formation, and the evolution of M82. “Since the co-discovery of the hydrogen 21-cm line by Dutch, American and Australian astronomers, we have been looking for a way to determine additional properties of the cold gas such as its temperature and density. It is fantastic that we now have found a way thanks to this carbon line. We can now collect more and better observations, and compare them to predictions from theoretical models,” says co-author Huub Röttgering (Leiden Observatory).

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New Study Shows Three Abrupt Pulse Of Carbon Dioxide During Last Deglaciation

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A new study shows that the rise of atmospheric carbon dioxide that contributed to the end of the last ice age more than 10,000 years ago did not occur gradually, but was characterized by three “pulses” in which C02 rose abruptly.
Scientists are not sure what caused these abrupt…

A new study shows that the rise of atmospheric carbon dioxide that contributed to the end of the last ice age more than 10,000 years ago did not occur gradually, but was characterized by three “pulses” in which C02 rose abruptly.
Scientists are not sure what caused these abrupt increases, during which C02 levels rose about 10-15 parts per million – or about 5 percent per episode – over a period of 1-2 centuries. It likely was a combination of factors, they say, including ocean circulation, changing wind patterns, and terrestrial processes.

The finding is important, however, because it casts new light on the mechanisms that take the Earth in and out of ice age regimes. Results of the study, which was funded by the National Science Foundation, appear this week in the journal Nature.

“We used to think that naturally occurring changes in carbon dioxide took place relatively slowly over the 10,000 years it took to move out of the last ice age,” said Shaun Marcott, lead author on the article who conducted his study as a post-doctoral researcher at Oregon State University. “This abrupt, centennial-scale variability of CO2 appears to be a fundamental part of the global carbon cycle.”

Some previous research has hinted at the possibility that spikes in atmospheric carbon dioxide may have accelerated the last deglaciation, but that hypothesis had not been resolved, the researchers say. The key to the new finding is the analysis of an ice core from the West Antarctic that provided the scientists with an unprecedented glimpse into the past.

Scientists studying past climate have been hampered by the limitations of previous ice cores. Cores from Greenland, for example, provide unique records of rapid climate events going back 120,000 years – but high concentrations of impurities don’t allow researchers to accurately determine atmospheric carbon dioxide records. Antarctic ice cores have fewer impurities, but generally have had lower “temporal resolution,” providing less detailed information about atmospheric CO2.

However, a new core from West Antarctica, drilled to a depth of 3,405 meters in 2011 and spanning the last 68,000 years, has “extraordinary detail,” said Oregon State paleoclimatologist Edward Brook, a co-author on the Nature study and an internationally recognized ice core expert. Because the area where the core was taken gets high annual snowfall, he said, the new ice core provides one of the most detailed records of atmospheric CO2.

“It is a remarkable ice core and it clearly shows distinct pulses of carbon dioxide increase that can be very reliably dated,” Brook said. “These are some of the fastest natural changes in CO2 we have observed, and were probably big enough on their own to impact the Earth’s climate.

“The abrupt events did not end the ice age by themselves,” Brook added. “That might be jumping the gun a bit. But it is fair to say that the natural carbon cycle can change a lot faster than was previously thought – and we don’t know all of the mechanisms that caused that rapid change.”

The researchers say that the increase in atmospheric CO2 from the peak of the last ice age to complete deglaciation was about 80 parts per million, taking place over 10,000 years. Thus, the finding that 30-45 ppm of the increase happened in just a few centuries was significant.

The overall rise of atmospheric carbon dioxide during the last deglaciation was thought to have been triggered by the release of CO2 from the deep ocean – especially the Southern Ocean. However, the researchers say that no obvious ocean mechanism is known that would trigger rises of 10-15 ppm over a time span as short as one to two centuries.

“The oceans are simply not thought to respond that fast,” Brook said. “Either the cause of these pulses is at least part terrestrial, or there is some mechanism in the ocean system we don’t yet know about.”

One reason the researchers are reluctant to pin the end of the last ice age solely on CO2 increases is that other processes were taking place, according to Marcott, who recently joined the faculty of the University of Wisconsin-Madison.
“At the same time CO2 was increasing, the rate of methane in the atmosphere was also increasing at the same or a slightly higher rate,” Marcott said. “We also know that during at least two of these pulses, the Atlantic Meridional Overturning Circulation changed as well. Changes in the ocean circulation would have affected CO2 – and indirectly methane, by impacting global rainfall patterns.”

“The Earth is a big coupled system,” he added, “and there are many pieces to the puzzle. The discovery of these strong, rapid pulses of CO2 is an important piece.”

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Existence Of A Group Of ‘Quiet’ Quasars Confirmed

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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…

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.

The more distant, the more luminous?

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.

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Tremendously Bright Pulsar May Be One Of Many

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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…

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.

Professor 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.”

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Physicists Closer To Understanding Balance Of Matter, Antimatter In Universe

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Physicists in the College of Arts and Sciences have made important discoveries regarding Bs meson particles — something that may explain why the universe contains more matter than antimatter.
Distinguished Professor Sheldon Stone and his colleagues recently announced their findings at a…

Physicists in the College of Arts and Sciences have made important discoveries regarding Bs meson particles — something that may explain why the universe contains more matter than antimatter.

Distinguished Professor Sheldon Stone and his colleagues recently announced their findings at a workshop at CERN in Geneva, Switzerland. Titled “Implications of LHCb Measurements and Their Future Prospects,” the workshop enabled him and other members of the Large Hadron Collider beauty (LHCb) Collaboration to share recent data results.

The LHCb Collaboration is a multinational experiment that seeks to explore what happened after the Big Bang, causing matter to survive and flourish in the Universe. LHCb is an international experiment, based at CERN, involving more than 800 scientists and engineers from all over the world. At CERN, Stone heads up a team of 15 physicists from Syracuse.

“Many international experiments are interested in the Bs meson because it oscillates between a matter particle and an antimatter particle,” says Stone, who heads up Syracuse’s High-Energy Physics Group. “Understanding its properties may shed light on charge-parity [CP] violation, which refers to the balance of matter and antimatter in the universe and is one of the biggest challenges of particle physics.”

Scientists believe that, 14 billion years ago, energy coalesced to form equal quantities of matter and antimatter. As the universe cooled and expanded, its composition changed. Antimatter all but disappeared after the Big Bang, leaving behind matter to create everything from stars and galaxies to life on Earth.

“Something must have happened to cause extra CP violation and, thus, form the universe as we know it,” Stone says.

He thinks part of the answer lies in the Bs meson, which contains an antiquark and a strange quark and is bound together by a strong interaction. (A quark is a hard, point-like object found inside a proton and neutron that forms the nucleus of an atom.)

Enter CERN, a European research organization that operates the world’s largest particle physics laboratory.

In Geneva, Stone and his research team — which includes Liming Zhang, a former Syracuse research associate who is now a professor at Tsinghua University in Beijing, China — have studied two landmark experiments that took place at Fermilab, a high-energy physics laboratory near Chicago, in 2009.

The experiments involved the Collider Detector at Fermilab (CDF) and the DZero (D0), four-story detectors that were part of Fermilab’s now-defunct Tevatron, then one of the world’s highest-energy particle accelerators.

“Results from D0 and CDF showed that the matter-antimatter oscillations of the Bs meson deviated from the standard model of physics, but the uncertainties of their results were too high to make any solid conclusions,” Stone says.
He and Zhang had no choice but to devise a technique allowing for more precise measurements of Bs mesons. Their new result shows that the difference in oscillations between the Bs and anti-Bs meson is just as the standard model has predicted.

Stone says the new measurement dramatically restricts the realms where new physics could be hiding, forcing physicists to expand their searches into other areas. “Everyone knows there is new physics. We just need to perform more sensitive analyses to sniff it out,” he adds.

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Peripheral Clocks Don’t Need The Brain’s Master Clock To Function Correctly

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Circadian clocks regulate functions ranging from alertness and reaction time to body temperature and blood pressure. New research published in the November 2014 issue of The FASEB Journal further adds to our understanding of the circadian rhythm by suggesting that the suprachiasmaticus nucleus…

Circadian clocks regulate functions ranging from alertness and reaction time to body temperature and blood pressure. New research published in the November 2014 issue of The FASEB Journal further adds to our understanding of the circadian rhythm by suggesting that the suprachiasmaticus nucleus (SCN) clock, a tiny region of the hypothalamus considered to be the body’s “master” timekeeper, is not necessary to align body rhythms with the light-dark cycle. This challenges and disproves the commonly held notion that circadian rhythms were strictly organized in a hierarchical manner, and that light resets the master clock in the SCN, which then coordinates the other, subordinate clocks in peripheral tissues. Several metabolic and psychiatric diseases are associated with circadian rhythm and sleep disturbances, and this research opens the doors toward an improved understanding of these disorders.

“Our study reveals a federal organization of internal clock synchronization with the environment,” said Henrik Oster, Ph.D., a researcher involved in the work from the Medical Department at the University of Lübeck in Lübeck, Germany. “This suggests that resetting specific peripheral tissue clocks may be an underestimated target for restoring circadian alignment, and possibly to counteract disorders associated with circadian rhythm disruption.”

To make this discovery, Oster and colleagues bred mice in which the molecular circadian clock had been deleted specifically in SCN pacemaker neurons, while leaving clocks in peripheral tissues untouched. These mice, as well as control mice with intact central and peripheral clocks, were then subjected to different lighting conditions. In a rhythmic light-dark environment, gene expression analysis revealed that both groups displayed rhythmic behavior, glucocorticoid hormone rhythms and clock gene expression rhythms in peripheral tissues such as liver or adrenal. When the mice were subjected to constant darkness conditions, behavioral rhythms in the SCN clock-less mice were immediately lost, while endocrine and molecular rhythms gradually dampened over the course of several days. Control mice retained stable rhythms at all levels throughout the experiment. Results suggest a revised model of circadian entrainment, with the adaptation of the internal clock by external time cue, resulting in a mode of photic entrainment in which light can in parallel reset central and peripheral clocks.

“For a long time, we’ve thought that the central clock in our brains is necessary to keep the other clocks in our body in time,” said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. “And this still correct most of the time in most people. This research is important, however, because it not only shows us what might be going wrong in folks with circadian-related disorders, but also helps us to understand how we can manipulate peripheral clocks to help these people.”

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