Longstanding Mystery of Sun's Hot Outer Atmosphere Solved

 One of the most enduring mysteries in solar physics is why the Sun's outer atmosphere, or corona, is millions of degrees hotter than its surface.

Now scientists believe they have discovered a major source of hot gas that replenishes the corona: jets of plasma shooting up from just above the Sun's surface.

The finding addresses a fundamental question in astrophysics: how energy is moved from the Sun's interior to create its hot outer atmosphere.

"It's always been quite a puzzle to figure out why the Sun's atmosphere is hotter than its surface," says Scott McIntosh, a solar physicist at the High Altitude Observatory of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., who was involved in the study.

"By identifying that these jets insert heated plasma into the Sun's outer atmosphere, we can gain a much greater understanding of that region and possibly improve our knowledge of the Sun's subtle influence on the Earth's upper atmosphere."

The research, results of which are published in the journal Science, was conducted by scientists from Lockheed Martin's Solar and Astrophysics Laboratory (LMSAL), NCAR, and the University of Oslo. It was supported by NASA and the National Science Foundation (NSF), NCAR's sponsor.
"These observations are a significant step in understanding observed temperatures in the solar corona," says Rich Behnke of NSF's Division of Atmospheric and Geospace Sciences, which funded the research.

"They provide new insight about the energy output of the Sun and other stars. The results are also a great example of the power of collaboration among university, private industry and government scientists and organizations."
The research team focused on jets of plasma known as spicules, which are fountains of plasma propelled upward from near the surface of the Sun into the outer atmosphere.

For decades scientists believed spicules could send heat into the corona. However, following observational research in the 1980s, it was found that spicule plasma did not reach coronal temperatures, and so the theory largely fell out of vogue.

"Heating of spicules to millions of degrees has never been directly observed, so their role in coronal heating had been dismissed as unlikely," says Bart De Pontieu, the lead researcher and a solar physicist at LMSAL.
In 2007, De Pontieu, McIntosh, and their colleagues identified a new class of spicules that moved much faster and were shorter-lived than the traditional spicules.

These "Type II" spicules shoot upward at high speeds, often in excess of 100 kilometers per second, before disappearing.

The rapid disappearance of these jets suggested that the plasma they carried
might get very hot, but direct observational evidence of this process was missing.

The researchers used new observations from the Atmospheric Imaging Assembly on NASA's recently launched Solar Dynamics Observatory and NASA's Focal Plane Package for the Solar Optical Telescope (SOT) on the Japanese Hinode satellite to test their hypothesis.

"The high spatial and temporal resolution of the newer instruments was crucial in revealing this previously hidden coronal mass supply," says McIntosh.

"Our observations reveal, for the first time, the one-to-one connection between plasma that is heated to millions of degrees and the spicules that insert this plasma into the corona."

The findings provide an observational challenge to the existing theories of coronal heating.

During the past few decades, scientists proposed a wide variety of theoretical models, but the lack of detailed observation significantly hampered progress.
"One of our biggest challenges is to understand what drives and heats the material in the spicules," says De Pontieu.

A key step, according to De Pontieu, will be to better understand the interface region between the Sun's visible surface, or photosphere, and its corona.

Another NASA mission, the Interface Region Imaging Spectrograph (IRIS), is scheduled for launch in 2012 to provide high-fidelity data on the complex processes and enormous contrasts of density, temperature and magnetic field between the photosphere and corona. Researchers hope this will reveal more about the spicule heating and launch mechanism.

The LMSAL is part of the Lockheed Martin Space Systems Company, which designs and develops, tests, manufactures and operates a full spectrum of advanced-technology systems for national security and military, civil government and commercial customers.

Narrow jets of material, called spicules, streak upward from the Sun's surface at high speeds. (Credit: NASA)

Prehistoric Bird Used Club-Like Wings as Weapon.

Paleontologists at Yale University and the Smithsonian Institution have discovered that Xenicibis, a member of the ibis family that lived about ten thousand years ago and was found only in Jamaica, most likely used its specialized wings like a flail, swinging its upper arm and striking its enemies with its thick hand bones.

"No animal has ever evolved anything quite like this," said Nicholas Longrich of Yale, who led the research. "We don't know of any other species that uses its body like a flail. It's the most specialized weaponry of any bird I've ever seen."
As part of the new study, the researchers analyzed a number of recently discovered partial skeletons of Xenicibis and found that the wings were drastically different from anything they'd seen before. "When I first saw it, I assumed it was some sort of deformity," Longrich said. "No one could believe it was actually that bizarre."

The bird, which was the size of a large chicken, is anatomically similar to other members of the ibis family except for its wings, which include thick, curved hand bones unlike those of any other known bird. Xenicibis also had a much larger breastbone and longer wings than most flightless birds. "That was our first clue that the wings were still being used for something," Longrich said.
While other birds are known to punch or hammer one another with their wings, Xenicibis is the only known animal to have used its hands, hinged at the wrist joint, like two baseball bats to swing at and strike its opponents. Although modern day ibises do not strike one another in this fashion, they are very territorial, with mates often fighting other pairs over nesting and feeding rights.
It's also possible that the birds used their club-like wings to defend themselves against other species that might have preyed on the birds' eggs or young. Xenicibis is unusual in that it became flightless even in the midst of a number of predators, including the Jamaican yellow boa, a small extinct monkey and over a dozen birds of prey.

The team found that two of the wing bones in the collection showed evidence of combat, including a fractured hand bone and a centimeter-thick upper arm bone that was broken in half. The damage is proof of the extreme force the birds were able to wield with their specialized wings, Longrich said.

The prehistoric Xenicibis used its wings like two clubs hinged at the wrist joint in order to swing at and attack one another. (Credit: Nicholas Longrich/Yale University)

'Nanoscoops' Could Spark New Generation of Electric Automobile Batteries.

An entirely new type of nanomaterial developed at Rensselaer Polytechnic Institute could enable the next generation of high-power rechargeable lithium (Li)-ion batteries for electric automobiles, as well as batteries for laptop computers, mobile phones, and other portable devices.

The new material, dubbed a "nanoscoop" because its shape resembles a cone with a scoop of ice cream on top, can withstand extremely high rates of charge and discharge that would cause conventional electrodes used in today's Li-ion batteries to rapidly deteriorate and fail. The nanoscoop's success lies in its unique material composition, structure, and size.

The Rensselaer research team, led by Professor Nikhil Koratkar, demonstrated how a nanoscoop electrode could be charged and discharged at a rate 40 to 60 times faster than conventional battery anodes, while maintaining a comparable energy density. This stellar performance, which was achieved over 100 continuous charge/discharge cycles, has the team confident that their new technology holds significant potential for the design and realization of high-power, high-capacity Li-ion rechargeable batteries.

"Charging my laptop or cell phone in a few minutes, rather than an hour, sounds pretty good to me," said Koratkar, a professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer. "By using our nanoscoops as the anode architecture for Li-ion rechargeable batteries, this is a very real prospect. Moreover, this technology could potentially be ramped up to suit the demanding needs of batteries for electric automobiles."

Batteries for all-electric vehicles must deliver high power densities in addition to high energy densities, Koatkar said. These vehicles today use supercapacitors to perform power-intensive functions, such as starting the vehicle and rapid acceleration, in conjunction with conventional batteries that deliver high energy density for normal cruise driving and other operations. Koratkar said the invention of nanoscoops may enable these two separate systems to be combined into a single, more efficient battery unit.

Results of the study were detailed in the paper "Functionally Strain-Graded Nanoscoops for High Power Li-Ion Battery Anodes," published Thursday by the journal Nano Letters.

The anode structure of a Li-ion battery physically grows and shrinks as the battery charges or discharges. When charging, the addition of Li ions increases the volume of the anode, while discharging has the opposite effect. These volume changes result in a buildup of stress in the anode. Too great a stress that builds up too quickly, as in the case of a battery charging or discharging at high speeds, can cause the battery to fail prematurely. This is why most batteries in today's portable electronic devices like cell phones and laptops charge very slowly -- the slow charge rate is intentional and designed to protect the battery from stress-induced damage.

The Rensselaer team's nanoscoop, however, was engineered to withstand this buildup of stress. Made from a carbon (C) nanorod base topped with a thin layer of nanoscale aluminum (Al) and a "scoop" of nanoscale silicon (Si), the structures are flexible and able to quickly accept and discharge Li ions at extremely fast rates without sustaining significant damage. The segmented structure of the nanoscoop allows the strain to be gradually transferred from the C base to the Al layer, and finally to the Si scoop. This natural strain gradation provides for a less abrupt transition in stress across the material interfaces, leading to improved structural integrity of the electrode.
The nanoscale size of the scoop is also vital since nanostructures are less prone to cracking than bulk materials, according to Koratkar.

"Due to their nanoscale size, our nanoscoops can soak and release Li at high rates far more effectively than the macroscale anodes used in today's Li-ion batteries," he said. "This means our nanoscoop may be the solution to a critical problem facing auto companies and other battery manufacturers -- how can you increase the power density of a battery while still keeping the energy density high?"

A limitation of the nanoscoop architecture is the relatively low total mass of the electrode, Koratkar said. To solve this, the team's next steps are to try growing longer scoops with greater mass, or develop a method for stacking layers of nanoscoops on top of each other. Another possibility the team is exploring includes growing the nanoscoops on large flexible substrates that can be rolled or shaped to fit along the contours or chassis of the automobile.
Along with Koratkar, authors on the paper are Toh-Ming Lu, the R.P. Baker Distinguished Professor of Physics and associate director of the Center for Integrated Electronics at Rensselaer; and Rahul Krishnan, a graduate student in the Department of Materials Science and Engineering at Rensselaer.

Researchers at Rensselaer Polytechnic Institute developed an entirely new type of nanomaterial that could enable the next generation of high-power rechargeable lithium (Li)-ion batteries for electric automobiles, laptop computers, mobile phones, and other devices. The material, called a “nanoscoop” because it resembles a cone with a scoop of ice cream on top, is shown in the above scanning electron microscope image. Nanoscoops can withstand extremely high rates of charge and discharge that would cause today’s Li-ion batteries to rapidly deteriorate and fail. (Credit: Image courtesy of Rensselaer Polytechnic Institute)

The Ecosystem Engineer: Research Looks at Beavers' Role in River Restoration.

Beavers are often called ecosystem engineers because they can radically alter stream or valley bottom ecosystems, said Melinda Daniels, an associate professor of geography who recently studied the connection between beavers and river restoration. Beaver dams create diverse river landscapes, she said, and can turn a single-thread channel stream into a meadow, pond or multichannel, free-flowing stream.

"Our argument is that the restoration target for streams with forested riparian zones has got to acknowledge the diversity brought to river systems by active beaver populations," Daniels said.
Daniels and three researchers from the University of Connecticut co-authored

"The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested Headwaters." The article, led by Denise Burchsted at the University of Connecticut, appears in a recent issue of BioScience, the journal of the American Institute of Biological Sciences.
While the research involves observations of several watersheds in northeastern Connecticut, the results are applicable to any forested stream, which typically have large beaver populations. Beaver populations have rebounded in recent years, Daniels said, after coming close to extinction in the early 19th century by hunters for their fur.

The ultimate goal of the research, Daniels said, is to help restore rivers in an efficient way that acknowledges ecosystem diversity and doesn't destroy it.
"A lot of rivers are in trouble and need work and restoration, but it's amazing how little we know about the systems we're trying to fix," she said. "We know they're broken, but we don't exactly know what they should look like because we know so little about how many of our river systems function."

Current restoration projects often don't consider the role of beavers as ecosystem engineers, and instead focus on creating continuous free-flowing streams, Daniels said. Such restoration can be expensive because it usually involves completely tearing down small 19th-century milldams and re-engineering an entire valley bottom.

Rather than tear down the whole milldam and radically change the surrounding ecosystem, the researchers recommend river restorers only remove part of it. This allows some ponded water to remain and mimics the role of beavers. Daniels said that in many cases if an old dam breaks and forms a gap, beavers may build their own dam to patch the gap and recreate the ecosystem that previously existed.

The researchers plan to continue river observations and collect more data to provide river restorers with insight for maintaining river ecosystem diversity.
"You can use these natural analogs to produce an ecosystem that looks a lot more like the one that was there before the colonists arrived," Daniels said. "We can restore rivers in a way that mimics the naturally diverse beaver streams, and we can save a lot of money in the process."

Beaver, cutting down a large oak tree. When engineers restore rivers, one Kansas State University professor hopes they'll keep a smaller engineer in mind: the North American beaver. (Credit: iStockphoto/Steve Greer)

Mariana Crow Will Go Extinct in 75 Years, Study Suggests

Researchers from the University of Washington say the Mariana crow, a forest crow living on Rota Island in the western Pacific Ocean, will go extinct in 75 years.

The extinction could happen almost twice as soon as previously believed.

The crow's extinction can be prevented with a bird management program that focuses on helping fledgling birds reach their first birthday, said James Ha, UW research associate professor in psychology.

Ha examined survival rates in 97 Mariana crows -- Corvus kubaryi -- that had been tracked between 1990 and 2010 by researchers. He found that 40 percent of fledgling crows made it to their first birthday.
The rapid decline of young birds is twice what researchers previously estimated.

"It's the first year of survival that's the most crucial," said Ha, lead author of a report on the research. "If only 40 percent of fledglings survive their first year, then we predict the species will go extinct in 75 years."

Ha and his co-authors published the report in the current issue of Bird Conservation International.

The 75-year extinction estimate is according to a population model that factors in the estimated number of existing Mariana crows -- 330 -- with the 40 percent first-year survival rate, average number of fledglings per nest and fertility of female birds. Using this model, Ha found that 91 birds would exist in 20 years and that in 75 years the species would be extinct.

Previously, biologists believed that the first-year survival rate of Mariana crows was higher, around 60 to 80 percent.

When Ha used those estimates in his population model, the outlook was not as grim for the birds. At 60 percent first-year survival rate, Mariana crows would dwindle to 218 birds in 20 years and become extinct in 133 years. And an 80 percent first-year survival rate projects that in 20 years there would be 453 birds, a growing population that would avoid extinction.

"According to the population model, if we can boost fledgling survival from 40 percent to 70 percent, the Mariana crows will be fine," Ha said.
Of the about 35 crow species, Mariana crows are considered rare and classified as critically endangered. Weighing about a half of a pound, Mariana crows are 40 percent smaller than other crows, such as the Northwest crow.

Monogamously-mating, Mariana crows live exclusively on Rota Island, populated by about 1,200 people and located 56 miles northeast of Guam. Rota is a U.S. territory and is up for consideration as a U.S. national park.
Ha and Renee Ha, co-author of the report and UW research scientist in psychology, fear that Rota faces the same avian demise as Guam, which has no
forest birds.

Brown tree snakes introduced to the island after World War II wiped out native birds, such as the Guam flycatcher and the Rufous fantail.
The Has suspect that the uncontrolled increase of feral cats on Rota is leading to the decrease of Mariana crows, much like brown tree snakes led to the disappearance of forest birds on Guam.

The researchers say that a captive rearing program could save the Mariana crows. They hope to set up a rearing facility where they could incubate eggs from the wild, raise the fledglings until their first birthday and then release the grown birds into nesting sites on the island.

The study was funded by the Commonwealth of the Northern Mariana Islands and the U.S. Fish and Wildlife Service. Co-author Alyssa Butler graduated from UW with a bachelor's degree in biology and is now a staff member at the Pali Institute, a science education camp in California.

This is a fledgling Mariana crow. (Credit: Sarah Faegre)

New Hot Jupiter-Like Exoplanet Discovered.

A Qatar astronomer teamed with scientists at the Harvard-Smithsonian Center for Astrophysics (CfA) and other institutions to discover a new alien world. This "hot Jupiter," now named Qatar-1b, adds to the growing list of alien planets orbiting distant stars.

The Qatar exoplanet survey hunts for stars that "wink," dimming slightly every time an orbiting planet creates a "mini-eclipse" by crossing in front of the star as seen from Earth. Transit searches like this must sift through thousands of stars to find the small fraction with detectable planets. The complex observations and analysis create perfect opportunities for teamwork.

To find the new world, Qatar's wide-angle cameras (located in New Mexico) took images of the sky every clear night beginning in early 2010. The photographs then were transmitted to the UK for analysis by collaborating astronomers at St. Andrews and Leicester Universities and Qatar. That analysis narrowed the field to a few hundred candidate stars.

The Harvard-Smithsonian team, with Dr. Al Subai, followed up on the most promising candidates, making spectroscopic observations with the 60-inch-diameter telescope at the Smithsonian's Whipple Observatory in Arizona. Such observations can weed out binary-star systems with grazing eclipses, which mimic planetary transits. They also measured the stars' dimming more accurately with Whipple's 48-inch telescope.

The resulting data confirmed the existence of a planet now called Qatar-1b, orbiting an orange Type K star 550 light-years away. Qatar-1b is a gas giant 20 percent larger than Jupiter in diameter and 10 percent more massive. It belongs to the "hot Jupiter" family because it orbits 2.2 million miles from its star -- only six stellar radii away. The planet roasts at a temperature of around 2,000 degrees Fahrenheit.

Qatar-1b circles its star once every 1.4 days, meaning that its "year" is just 34 hours long. It's expected to be tidally locked with the star, so one side of the planet always faces the star. As a result, the planet spins on its axis once every 34 hours -- three times slower than Jupiter, which rotates once in 10 hours.

The newly-discovered alien world Qatar-1b orbits an orange type K star 550 light-years from Earth. Qatar-1b is a gas giant 20 percent larger than Jupiter in diameter and 10 percent more massive. It circles its star once every 1.4 days, meaning that its "year" is just 34 hours long. (Credit: David A. Aguilar (CfA))

Tsunami Risk Higher in Los Angeles, Other Major Cities Than Thought, Haiti Study Suggests.

Like Haiti's capital, these cities all lie near the coast and near an active geologic feature called a strike-slip fault where two tectonic plates slide past each other like two hands rubbing against each other.

Until now, geologists did not consider the tsunami risk to be very high in these places because when these faults rupture, they usually do not vertically displace the seafloor much, which is how most tsunamis are generated. This latest research suggests even a moderate earthquake on a strike-slip fault can generate tsunamis through submarine landslides, raising the overall tsunami risk in these places.

"The scary part about that is you do not need a large earthquake to trigger a large tsunami," said Matt Hornbach, research associate at The University of Texas at Austin's Institute for Geophysics and lead author on a paper describing the research in the Oct. 10 online edition of the journal Nature Geoscience.

"Organizations that issue tsunami warnings usually look for large earthquakes on thrust faults," said Hornbach. "Now we see you don't necessarily need those things. A moderate earthquake on a strike-slip fault can still be cause for alarm."

Within minutes after the magnitude 7 Haiti earthquake, a series of tsunami waves, some as high as 9 feet (3 meters), crashed into parts of the shoreline. A few weeks later, a team of scientists from the U.S. and Haiti conducted geological field surveys of sites on and offshore near the quake's epicenter.
The scientists determined the tsunamis were generated primarily by weak sediment at the shore that collapsed and slid along the seafloor, displacing the overlying water. Combined with newly discovered evidence of historic tsunamis, the survey revealed a third of all tsunamis in the area are generated in this way. Geologists had previously estimated only about 3 percent of tsunamis globally are generated through submarine landslides.

"We found that tsunamis around Haiti are about 10 times more likely to be generated in this way than we would have expected," said Hornbach.
In addition to Hornbach, team members from The University of Texas at Austin include: Paul Mann, Fred Taylor, Cliff Frohlich, Sean Gulick and Marcy Davis. The team also includes researchers from Queens College, City University of New York; U.S. Geological Survey, University of Missouri; Lamont-Doherty Earth Observatory of Columbia University; University of California, Santa Barbara; Bureau of Mines and Energy (Haiti); and Universite d'Etat de Haiti.

The researchers gathered data on faults beneath the seafloor and land, vertical movement of the land, bathymetry (underwater topography) of the seafloor and evidence of tsunami waves. They worked on foot, on a small inflatable boat and on the 165-foot research vessel Endeavor.

This research was funded by a Rapid Response grant from the National Science Foundation and The University of Texas at Austin's Jackson School of Geosciences.

With additional funding from The Society for Geophysics' Geoscientists Without Borders program, Hornbach and others are now conducting a new research project in nearby Jamaica to assess the tsunami threat there.

"The geology of Kingston, Jamaica is nearly identical to Port Au Prince, Haiti," said Hornbach. "It's primed and ready to go and they need to prepare for it. The good news is, they have a leg up because they're aware of the problem."

Following the Jan. 12 Haiti earthquake, sediments near the town of Grand Goave slid into the sea, triggering a tsunami. Satellite images before (top left) and after (bottom left) show the location of the landslide. Seafloor bathymetry collected with sonar (right) reveals the slide path. (Credit: Image courtesy of University of Texas at Austin)