[Karen W.]

 
Red Orbit breaking News

http://www.redorbit.com/news/display/?id=747011

Posted on: Tuesday, 28 November 2006, 13:35 CST
Study Finds that a Single Impact Killed the Dinosaurs



Data supports the single-impact theory in a controversial discussion

COLUMBIA, Mo. – The dinosaurs, along with the majority of all other animal species on Earth, went extinct approximately 65 million years ago. Some scientists have said that the impact of a large meteorite in the Yucatan Peninsula, in what is today Mexico, caused the mass extinction, while others argue that there must have been additional meteorite impacts or other stresses around the same time.

A new study provides compelling evidence that "one and only one impact" caused the mass extinction, according to a University of Missouri-Columbia researcher.

"The samples we found strongly support the single impact hypothesis," said Ken MacLeod, associate professor of geological sciences at MU and lead investigator of the study. "Our samples come from very complete, expanded sections without deposits related to large, direct effects of the impact – for example, landslides – that can shuffle the record, so we can resolve the sequence of events well. What we see is a unique layer composed of impact-related material precisely at the level of the disappearance of many species of marine plankton that were contemporaries of the youngest dinosaurs. We do not find any sedimentological or geochemical evidence for additional impacts above or below this level, as proposed in multiple impact scenarios."

MacLeod and his co-investigators studied sediment recovered from the Demerara Rise in the Atlantic Ocean northeast of South America, about 4,500 km (approximately 2,800 miles) from the impact site on the Yucatan Peninsula. Sites closer to and farther from the impact site have been studied, but few intermediary sites such as this have been explored.

Interpretation of samples from locations close to the crater are complicated by factors such as waves, earthquakes and landslides that likely followed the impact and would have reworked the sediment. Samples from farther away received little impact debris and often don’t demonstrably contain a complete record of the mass extinction interval. The Demerara Rise samples, thus, provide an unusually clear picture of the events at the time of the mass extinction.

"With our samples, there just aren’t many complications to confuse interpretation. You could say that you’re looking at textbook quality samples, and the textbook could be used for an introductory class," MacLeod said. "It’s remarkable the degree to which our samples follow predictions given a mass extinction caused by a single impact. Sedimentological and paleontological complexities are minor, the right aged-material is present, and there is no support for multiple impacts or other stresses leading up to or following the deposition of material from the impact."

The impact of a meteorite on the Yucatan Peninsula likely caused massive earthquakes and tsunamis. Dust from the impact entered the atmosphere and blocked sunlight, causing plants to die and animals to lose important sources of food. Temperatures probably cooled significantly around the globe before warming in the following centuries, wildfires on an unprecedented scale may have burned and acid rain might have poured down.

MacLeod and many other scientists believe that these effects led to the relatively rapid extinction of most species on the planet. Some other scientists have argued that a single impact could not have caused the changes observed and say that the impact in the Yucatan predates the mass extinction by 300,000 years.

MacLeod’s co-investigators were Donna L. Whitney from the University of Minnesota, Brian T. Huber from the Smithsonian National Museum of Natural History and Christian Koeberl of the University of Vienna. The study was recently published in the ‘in press’ section of the online version of the Geological Society of America Bulletin. Funding was provided by the U.S. Science Support Program, the U.S. National Science Foundation and the Austrian Science Foundation. Samples were recovered on Leg 207 of the Ocean Drilling Program.

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[neilep (OP)]

Astronomers study a star born soon after the Big Bang
McDONALD OBSERVATORY NEWS RELEASE


AUSTIN ‹ How old are the oldest stars? An international team of astronomers led by Dr. Anna Frebel of The University of Texas at Austin McDonald Observatory recently measured the age of an ancient star in our Milky Way galaxy at an extraordinary 13.2 billion years. This measurement provides a lower limit to the age of the universe and will help to disentangle the chemical history of our galaxy. Frebel's results are published in today's edition of The Astrophysical Journal Letters.

The team used radioactive decay dating techniques to date the star, called HE 1523-0901. This is close to the age of the universe of 13.7 billion years. "This guy was born very shortly after the Big Bang," Frebel said.

"Surprisingly, it is very hard to pin down the age of a star," she said, "although we can generally infer that chemically primitive stars have to be very old." Such stars must have been born before many generations of stars had chemically enriched our galaxy.

Astronomers can only accurately measure the ages of very rare old stars that contain huge amounts of certain types of chemical elements, including radioactive elements like thorium and uranium.

Similar to the way archaeologists use carbon-14 and other elements to date Earth relics thousands of years old, astronomers use radioactive elements found in stars to deduce these stars' ages, which may be millions or billions of years.

"Very few stars display radioactive elements," Frebel said. "I'm looking at a very rare subgroup of these already rare stars. I'm looking for a needle in a haystack, really."

Frebel made the extremely difficult measurement of the amount of uranium in the star HE 1523-0901 using the UVES spectrograph on the Kueyen Telescope, one of four 8.2-meter telescopes that comprise The Very Large Telescope at the European Southern Observatory in Chile.

"This star is the best uranium detection so far," she said, explaining that while uranium has been discovered in two other stars previously, only one could be used to get a good age for the star. HE 1523-0901 also contains thorium, another radioactive element that is useful in age-dating of stars. Uranium, with a half-life of 4.5 billion years, is a better clock than thorium, Frebel says. Thorium's half-life of 14 billion years is actually longer than the age of the universe.

But astronomers need more than just radioactive elements like uranium and thorium to age-date a star. For each radioactive element, "you have to anchor it to another element within the star," Frebel said. Because she detected so many of these anchor elements in HE 1523-0901, she can come up with an extremely accurate age. In this case, the anchor elements are europium, osmium, and iridium.

The combination of two radioactive elements with three anchor elements discovered in this one star provided Frebel six so-called "cosmic clocks."

"So far, for no other star was it possible to employ more than one cosmic clock," she said. "Now we are suddenly provided with six measurements in just one star!"

How did she find this amazing star? Frebel says it was a case of "informed serendipity." She was researching a sample of old stars for her PhD thesis while a graduate student at The Australian National University, and recognized the consequences of this star's extraordinary spectrum after she measured it with ESO's Very Large Telescope.

"When you do discovery work, you never know what you're going to find," Frebel said. "You hope to find interesting objects. Depending on what you find, you then move in that direction."

The new result will be used by Frebel and her team to gain important clues to the creation and evolution of the chemical elements shortly after the Big Bang. It will also provide theorists with new, important experimental data. "Stars such as HE 1523-0901 are ideal cosmic laboratories to study nucleosynthesis," she said.

Frebel is now working with her colleagues Chris Sneden, Volker Bromm, Carlos Allende Prieto, Matthew Shetrone, and graduate student Ian Roederer at The University of Texas at Austin to further research extremely old stars with the 9.2-meter Hobby-Eberly Telescope at McDonald Observatory.

The Hobby-Eberly Telescope is a joint project of The University of Texas at Austin, The Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitat Munchen and Georg-August-Unversitat Gottingen.

SOURCE:SPACEFLIGHTNOW.com

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Exotic extrasolar planet is the hottest yet discovered
UNIVERSITY OF CENTRAL FLORIDA NEWS RELEASE


ORLANDO - University of Central Florida Physics Professor Joseph Harrington and his team have measured the hottest planet ever at 3700 degrees Fahrenheit.

"HD 149026b is simply the most exotic, bizarre planet," Harrington said. "It's pretty small, really dense, and now we find that it's extremely hot."



 
 
Using Spitzer, NASA's infrared space telescope, Harrington and his team observed the tiny planet disappear behind its star and reappear. Although the planet cannot be seen separately from the star, the dimming of the light that reached Spitzer told the scientists how much light the hot planet emits. From this they deduced the temperature on the side of the planet facing its star. The team's findings were published online in Nature today.

Discovered in 2005, HD 149026b is a bit smaller than Saturn, making it the smallest extrasolar planet with a measured size. However, it is more massive than Saturn, and is suspected of having a core 70-90 times the mass of the entire Earth. It has more heavy elements (material other than hydrogen and helium) than exist in our whole solar system, outside the Sun.

There are more than 230 extrasolar planets, but this is only the fourth of these to have its temperature measured directly. It is simple to explain the temperatures of the other three planets. However, for HD 149026b to reach 3700 degrees, it must absorb essentially all the starlight that reaches it. This means the surface must be blacker than charcoal, which is unprecedented for planets. The planet would also have to re-radiate all that energy in the infrared.

"The high heat would make the planet glow slightly, so it would look like an ember in space, absorbing all incoming light but glowing a dull red," said Harrington.

Drake Deming, of NASA's Goddard Space Flight Center in Greenbelt, MD, and a co-author of the Nature paper, thinks theorists are going to be scratching their heads over this one. "This planet is off the temperature scale that we expect for planets, so we don't really understand what's going on," Deming said. "There may be more big surprises in the future."

Harrington's team on this project also included Statia Luszcz from the Center for Radiophysics and Space Research at Cornell University, who is now a graduate student at the University of California, Berkeley. Sara Seager, a theorist in the Departments of Earth, Atmospheric, and Planetary Sciences and of Physics at the Massachusetts Institute of Technology, and Jeremy Richardson, an observer from the Exoplanet and Stellar Astrophysics Laboratory at NASA Goddard, round out the team.

Harrington is no stranger to significant findings. His research was published in Science magazine in October 2006 and in Nature in February 2007. In the first of those papers, Harrington's team used Spitzer to make the first measurement of day and night temperature variation on a different extrasolar planet. That research found that a Jupiter-like gas-giant planet circling very close to its sun is as hot as fire on one side, and potentially as cold as ice on the other, a condition that may also hold for HD 149026b.

February's publication documented a landmark achievement. In a project led by Richardson, the group captured enough light from an exoplanet to spread it apart into a spectrum and find signatures of molecules in the planet's atmosphere -- a key step toward being able to detect life on alien worlds.

Harrington's team fared well in this year's stiff competition for observing time on NASA's orbiting infrared facility. They will observe HD 149026b using all of Spitzer's instruments in the coming year, to gain a better understanding of the planet's atmosphere. Harrington is a professor in UCF's growing program in planetary sciences.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center, Pasadena, Calif. JPL is a division of California Institute for Technology, Pasadena.

[neilep (OP)]

Scientist finds a new way to the center of the Earth
NASA/JPL NEWS RELEASE


PASADENA, Calif. -- Humans have yet to see Earth's center, as did the characters in Jules Verne's science fiction classic, "Journey to the Center of the Earth." But a new NASA study proposes a novel technique to pinpoint more precisely the location of Earth's center of mass and how it moves through space.

Knowing the location of the center of mass, determined using measurements from sites on Earth's surface, is important because it provides the reference frame through which scientists determine the relative motions of positions on Earth's surface, in its atmosphere and in space. This information is vital to the study of global sea level change, earthquakes, volcanoes and Earth's response to the retreat of ice sheets after the last ice age.

The accuracy of estimates of the motion of Earth's center of mass is uncertain, but likely ranges from 2 to 5 millimeters (.08 to .20 inches) a year. Donald Argus of NASA's Jet Propulsion Laboratory, Pasadena, Calif., developed the new technique, which estimates Earth's center of mass to within 1 millimeter (.04 inches) a year by precisely positioning sites on Earth's surface using a combination of four space-based techniques. The four techniques were developed and/or operated by NASA in partnership with other national and international agencies. Results of the new study appear in the June issue of Geophysical Journal International.

Scientists currently define Earth's center in two ways: as the mass center of solid Earth or as the mass center of Earth's entire system, which combines solid Earth, ice sheets, oceans and atmosphere. Argus says there is room for improvement in these estimates.

"The past two international estimates of the motion of the Earth system's mass center, made in 2000 and 2005, differ by 1.8 millimeters (.07 inches) a year," he said. "This discrepancy suggests the motion of Earth's mass center is not as well known as we'd like."

Argus argues that movements in the mass of Earth's atmosphere and oceans are seasonal and do not accumulate enough to change Earth's mass center. He therefore believes the mass center of solid Earth provides a more accurate reference frame.

"By its very nature, Earth's reference frame is moderately uncertain no matter how it is defined," Argus said. "The problem is very much akin to measuring the center of mass of a glob of Jell-O, because Earth is constantly changing shape due to tectonic and climatic forces. This new reference frame takes us a step closer to pinpointing Earth's exact center."

Argus says this new reference frame could make important contributions to understanding global climate change. The inference that Earth is warming comes partly from observations of global sea level rise, believed to be due to ice sheets melting in Greenland, Antarctica and elsewhere. In recent years, global sea level has been rising faster, with the current rate at about 3 millimeters (.12 inches) a year. Uncertainties in the accuracy of the motion of Earth's center of mass result in significant uncertainties in measuring this rate of change.

"Knowing the relative motions of the mass center of Earth's system and the mass center of the solid Earth can help scientists better determine the rate at which ice in Greenland and Antarctica is melting into the ocean," Argus explained. He said the new frame of reference will improve estimates of sea level rise from satellite altimeters like the NASA/French Space Agency Jason satellite, which rely on measurements of the location and motion of the mass center of Earth's system.

"For scientists studying post-glacial rebound, this new reference frame helps them better understand how viscous [gooey or sticky] Earth's solid mantle is, which affects how fast Earth's crust rises in response to the retreat of the massive ice sheets that covered areas such as Canada 20,000 years ago," he said. "As a result, they'll be able to make more accurate estimates of these vertical motions and can improve model predictions."

Scientists can also use the new information to more accurately determine plate motions along fault zones, improving our understanding of earthquake and volcanic processes.

The new technique combines data from a high-precision network of global positioning system receivers; a network of laser stations that track high-orbiting geodetic satellites called Laser Geodynamics Satellites, or Lageos; a network of radio telescopes that measure the position of Earth with respect to quasars at the edge of the universe, known as very long baseline interferometry; and a French network of precise satellite tracking instruments called Doppler Orbit and Radiopositioning Integrated by Satellite, or DORIS.

JPL is managed for NASA by the California Institute of Technology in Pasadena.

SOURCE:SPACEFLIGHTNOW.com

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New research proves single origin of humans in Africa
New research published in the journal Nature (19 July) has proved the single origin of humans theory by combining studies of global genetic variations in humans with skull measurements across the world. The research, at the University of Cambridge and funded by the Biotechnology and Biological Sciences Research Council (BBSRC), represents a final blow for supporters of a multiple origins of humans theory.

Competing theories on the origins of anatomically modern humans claim that either humans originated from a single point in Africa and migrated across the world, or different populations independently evolved from homo erectus to home sapiens in different areas.

The Cambridge researchers studied genetic diversity of human populations around the world and measurements of over 6,000 skulls from across the globe in academic collections. Their research knocks down one of the last arguments in favour of multiple origins. The new findings show that a loss in genetic diversity the further a population is from Africa is mirrored by a loss in variation in physical attributes.

Lead researcher, Dr Andrea Manica from the University's Department of Zoology, explained: "The origin of anatomically modern humans has been the focus of much heated debate. Our genetic research shows the further modern humans have migrated from Africa the more genetic diversity has been lost within a population.

"However, some have used skull data to argue that modern humans originated in multiple spots around the world. We have combined our genetic data with new measurements of a large sample of skulls to show definitively that modern humans originated from a single area in Sub-saharan Africa."

The research team found that genetic diversity decreased in populations the further away from Africa they were - a result of 'bottlenecks' or events that temporarily reduced populations during human migration. They then studied an exceptionally large sample of human skulls. Taking a set of measurements across all the skulls the team showed that not only was variation highest amongst the sample from south eastern Africa but that it did decrease at the same rate as the genetic data the further the skull was away from Africa.

To ensure the validity of their single origin evidence the researchers attempted to use their data to find non-African origins for modern humans. Research Dr Francois Balloux explains: "To test the alternative theory for the origin of modern humans we tried to find an additional, non-African origin. We found this just did not work. Our findings show that humans originated in a single area in Sub-Saharan Africa."


SOURCE: EUREKALERT.ORG

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Supergiant star spews molecules needed for life
UNIVERSITY OF ARIZONA NEWS RELEASE
Posted: July 30, 2007

University of Arizona astronomers who are probing the oxygen-rich environment around a supergiant star with one of the world's most sensitive radio telescopes have discovered a score of molecules that include compounds needed for life.

"I don't think anyone would have predicted that VY Canis Majoris is a molecular factory. It was really unexpected," said Arizona Radio Observatory (ARO) Director Lucy Ziurys, UA professor of astronomy and of chemistry. "Everyone thought that the interesting chemistry in gas clouds around old stars was happening in envelopes around nearer, carbon-rich stars," Ziurys said. "But when we started looking closely for the first time at an oxygen-rich object, we began finding all these interesting things that weren't supposed to be there."

VY Canis Majoris, one of the most luminous infrared objects in the sky, is an old star about 5,000 light years away. It's a half million times more luminous than the sun, but glows mostly in the infrared because it's a cool star. It truly is "supergiant" -- 25 times as massive as the sun and so huge that it would fill the orbit of Jupiter. But the star is losing mass so fast that in a million years -- an astronomical eyeblink -- it will be gone. The star already has blown away a large part of its atmosphere, creating its surrounding envelope that contains about twice as much oxygen as carbon.

Ziurys and her colleagues are not yet halfway through their survey of VY Canis Majoris, but they've already published in the journal, Nature (June 28 issue), about their observations of a score of chemical compounds. These include some molecules that astronomers have never detected around stars and are needed for life.

Among the molecules Ziurys and her team reported in Nature are table salt (NaCl); a compound called phosphorus nitride (PN), which contains two of the five most necessary ingredients for life; molecules of HNC, which is a variant form of the organic molecule, hydrogen cyanide; and an ion molecule form of carbon monoxide that comes with a proton attached (HCO+). Astronomers have found very little phosphorus or ion molecule chemistry in outflows from cool stars until now.

"We think these molecules eventually flow from the star into the interstellar medium, which is the diffuse gas between stars. The diffuse gas eventually collapses into denser molecular clouds, and from these solar systems eventually form," Ziurys said.

Comets and meteorites dump about 40,000 tons of interstellar dust on Earth each year. We wouldn't be carbon-based life forms otherwise, Ziurys noted, because early Earth lost all of its original carbon in the form of a methane atmosphere.

"The origin of organic material on Earth -- the chemical compounds that make up you and me -- probably came from interstellar space. So one can say that life's origins really begin in chemistry around objects like VY Canis Majoris."

Astronomers previously studied VY Canis Majoris with optical and infrared telescopes. "But that's kind of like diving in with a butcher knife to look at what's there, when what you need is an oyster fork," Ziurys said.

The Arizona Radio Observatory's 10-meter Submillimeter Telescope (SMT) on Mount Graham, Ariz., excels as a sensitive stellar "oyster fork." Chemical molecules each possess their own unique radio frequencies. The astronomers identify the unique radio signatures of chemical compounds in laboratory work, enabling them to identify the molecules in space.

The ARO team recently began testing a new receiver in collaboration with the National Radio Astronomy Observatory. The receiver was developed as a prototype for the Atacama Large Millimeter Array, a telescope under construction in Chile. The state-of-the-art receiver has given the SMT 10 times more sensitivity at millimeter wavelengths than any other radio telescope. The SMT can now detect emission weaker than a typical light bulb from distant space at very precise frequencies.

The UA team has discovered that the molecules aren't just flowing out as a gas sphere around VY Canis Majoris, but also are blasting out as jets through the spherical envelope.

"The signals we receive show not only which molecules are seen, but how the molecules are moving toward and away from us," said Stefanie Milam, a recent doctoral graduate on the ARO team.

The molecules flowing out from VY Canis Majoris trace complex winds in three outflows: the general, spherical outflow from the star, a jet of material blasting out towards Earth, and another jet shooting out a 45 degree angle away from Earth.

Astronomers have seen bipolar outflows from stars before, but not two, unconnected, asymmetric and apparently random outflows, Ziurys said.

Ziurys said she believes the two random jets are evidence for what astronomers earlier proposed are "supergranules" that form in very massive stars, and has been seen in Betelgeuse. Supergranules are huge cells of gas that form inside the star, then float to the surface and are ejected out of the star, where they cool in space and form molecules, creating jet outflows with certain molecular compositions.

Back in the 1960s, no one believed molecules could survive the harsh environment of space. Ultraviolet radiation supposedly reduced matter to atoms and atomic ions. Now scientists conclude that at least half of the gas in space between the stars within the 33-light-year inner galaxy is molecular, Ziurys said. "Our results are more evidence that we live in a really molecular universe, as opposed to an atomic one," Ziurys said.

The Arizona Radio Observatory (ARO) owns and operates two radio telescopes in southern Arizona: The former NRAO 12 Meter (KP12m) Telescope located 50 miles southwest of Tucson on Kitt Peak and the Submillimeter Telescope (SMT) located on Mount Graham near Safford, Ariz. The telescopes are operated around-the-clock for about nine to 10 months per year for a combined 10,000 hours per observing season. About 1,500 hours are dedicated to sub-mm wavelengths at the SMT. The ARO offices are centrally located in the Steward Observatory building on the UA campus in Tucson.


SOURCE: http://spaceflightnow.com/news/n0707/30supergiant/

[neilep (OP)]

Satellites unveil new type of active galaxy
NASA-GODDARD NEWS RELEASE
Posted: July 30, 2007

GREENBELT, Md. - An international team of astronomers using NASA's Swift satellite and the Japanese/U.S. Suzaku X-ray observatory has discovered a new class of active galactic nuclei (AGN).

By now, you'd think that astronomers would have found all the different classes of AGN - extraordinarily energetic cores of galaxies powered by accreting supermassive black holes. AGN such as quasars, blazars, and Seyfert galaxies are among the most luminous objects in our Universe, often pouring out the energy of billions of stars from a region no larger than our solar system. (NEIL EDIT: HOLY COW !!!!....that's well bright !!!)


But by using Swift and Suzaku, the team has discovered that a relatively common class of AGN has escaped detection...until now. These objects are so heavily shrouded in gas and dust that virtually no light gets out.

"This is an important discovery because it will help us better understand why some supermassive black holes shine and others don't," says astronomer and team member Jack Tueller of NASA's Goddard Space Flight Center in Greenbelt, Md.

Evidence for this new type of AGN began surfacing over the past two years. Using Swift's Burst Alert Telescope (BAT), a team led by Tueller has found several hundred relatively nearby AGNs that were previously missed because their visible and ultraviolet light was smothered by gas and dust. The BAT was able to detect high-energy X-rays from these heavily blanketed AGNs because, unlike visible light, high-energy X-rays can punch through thick gas and dust.

To follow up on this discovery, Yoshihiro Ueda of Kyoto University, Japan, Tueller, and a team of Japanese and American astronomers targeted two of these AGNs with Suzaku. They were hoping to determine whether these heavily obscured AGNs are basically the same type of objects as other AGN, or whether they are fundamentally different. The AGNs reside in the galaxies ESO 005-G004 and ESO 297-G018, which are about 80 million and 350 million light-years from Earth, respectively.

Suzaku covers a broader range of X-ray energies than BAT, so astronomers expected Suzaku to see X-rays across a wide swath of the X-ray spectum. But despite Suzaku's high sensitivity, it detected very few low- or medium-energy X-rays from these two AGN, which explains why previous X-ray AGN surveys missed them.

According to popular models, AGNs are surrounded by a donut-shaped ring of material, which partially obscures our view of the black hole. Our viewing angle with respect to the donut determines what type of object we see. But team member Richard Mushotzky, also at NASA Goddard, thinks these newly discovered AGN are completely surrounded by a shell of obscuring material. "We can see visible light from other types of AGN because there is scattered light," says Mushotzky. "But in these two galaxies, all the light coming from the nucleus is totally blocked."

Another possibility is that these AGN have little gas in their vicinity. In other AGN, the gas scatters light at other wavelengths, which makes the AGN visible even if they are shrouded in obscuring material.

"Our results imply that there must be a large number of yet unrecognized obscured AGNs in the local universe," says Ueda.

In fact, these objects might comprise about 20 percent of point sources comprising the X-ray background, a glow of X-ray radiation that pervades our Universe. NASA's Chandra X-ray Observatory has found that this background is actually produced by huge numbers of AGNs, but Chandra was unable to identify the nature of all the sources.

By missing this new class, previous AGN surveys were heavily biased, and thus gave an incomplete picture of how supermassive black holes and their host galaxies have evolved over cosmic history. "We think these black holes have played a crucial role in controlling the formation of galaxies, and they control the flow of matter into clusters," says Tueller. "You can't understand the universe without understanding giant black holes and what they're doing. To complete our understanding we must have an unbiased sample."

The discovery paper will appear in the August 1st issue of the Astrophysical Journal Letters.

SOURCE:http://spaceflightnow.com/news/n0707/30galaxy/

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Planet orbiting a giant red star discovered


A planet orbiting a giant red star has been discovered by an astronomy team led by Penn State's Alex Wolszczan, who in 1992 discovered the first planets ever found outside our solar system. The new discovery is helping astronomers to understand what will happen to the planets in our solar system when our Sun becomes a red-giant star, expanding so much that its surface will reach as far as Earth's orbit.

The star is 2 times more massive and 10 times larger than the Sun. The new planet circles the giant star every 360 days and is located about 300 light years from Earth, in the constellation Perseus. A paper describing the discovery will be published in a November 2007 issue of the Astrophysical Journal.

The discovery resulted from an ongoing effort that the research team began three years ago to find Jupiter-mass planets around red-giant stars that are typically farther from Earth than those included in most other planet searches.

"After astronomers have spent more than 10 years searching for planets around Sun-like stars and discovering over 250 planets elsewhere in our galactic neighborhood, we still do not know whether our solar system's properties, including life-supporting conditions on our planet, are typical or exceptional among solar systems throughout the Galaxy," Wolszczan says. "The picture for now, based on the searches for planets around stars like our Sun, is that our planetary system appears to be unusual in a number of ways."

"This planet is the first one discovered by Penn State astronomers with the Hobby-Eberly Telescope, and it is in one of the most distant of the ten published solar systems discovered around red-giant stars," comments Lawrence Ramsey, a member of the discovery team and the head of the Department of Astronomy and Astrophysics at Penn State. Ramsey is a leader in the conception, design, construction, and operation of the Hobby-Eberly Telescope. "We are now becoming serious participants in planetary searches and planetary astronomy using the Hobby-Eberly Telescope," he says.

Astronomers now are branching out with different strategies for searching for planets, with the hope of more quickly detecting life elsewhere in the universe, of discovering all the possible kinds of solar systems, and of learning how they form around different kinds of stars. Wolszczan's team used one of these new strategies -- searching for planets around giant stars, which have evolved to a later stage of life than our Sun's.

"We have compiled a catalog of nearly a thousand giant stars that are candidates for hosting solar systems," Wolszczan says.

Because the method for discovering planets involves repeated measurements of their gravitational effect on the star they circle, and because planets around red giants can take years to make one orbit around the star, the research team is just now beginning to reap discoveries from years of systematic observations.

"It took us 3 years to gather enough data on over 300 stars to start identifying those that are good candidates for having planetary companions," Wolszczan said. "This planet is just the first of a number of planet discoveries that this research program is likely to produce."

This research is a collaboration between astronomers at Penn State, Nicholas Copernicus University in Poland, the McDonald Observatory, and the California Institute of Technology.

"One important aspect of this work is that it marks the debut of a research group in Poland, led by Dr. Andrzej Niedzielski, which has become a serious contributor to discoveries in extra-solar planetary astronomy," Wolszczan said.

One reason for studying solar systems that include red-giant stars is that they help astronomers to understand more about the future of our own solar system -- as family photos can give children an idea of what they might look like when they are the age of their grandparents.

"Our Sun probably will make the Earth unhabitable in about 2 billion years because it will get hotter and hotter as it evolves on its way to becoming a red giant about 5 billion years from now," Wolszczan says.

As the star swells up, transforming itself into a red giant, it affects the orbits of its planets and the dynamics of the whole planetary system, causing such changes as orbit crossings, planet collisions, and the formation of new planets out of the debris of those collisions.

"When our Sun becomes a red giant, Earth and the other inner planets very likely will dive into it and disappear," Wolszczan says.

Another motivation for studying red-giant stars is to understand how their habitable zones move farther out as the star's radiating surface becomes bigger. Based on how long it took for life to develop on Earth, scientists speculate that there is more than enough time during a star's giant phase for life to get a start somewhere in the evolving habitable zones.

"In our solar system, places like Europa -- a satellite of Jupiter that now is covered by a thick layer of water ice -- might warm up enough to support life for more than a billion years or so, over the time when our Sun begins to evolve into a red giant, making life on Earth impossible," Wolszczan said.

The method the astronomers use to discover planets is to observe candidate stars, repeatedly measuring their space velocity using the Doppler effect -- the changes in the star's light spectrum that result from its being pulled alternately toward and away from Earth by the gravity of an orbiting planet.

"When we detect a significant difference in a star's velocity over a month or two, we then start observing that star more frequently," Wolszczan says. "In this paper, the velocity of the star changed by about 50 meters per second (about 100 miles per hour) between our first and second observations, so we observed that star more frequently and we found a clearly repeatable effect, indicating the presence of a planet." A star and its orbiting planet move around the center-of-mass of the whole system, so the star alternately approaches and recedes from Earth periodically. "When the star gets closer to us, its light becomes a little bit bluer and when it recedes from us, its light becomes redder, and we can measure that effect to deduce the presence of planets," Wolszczan explains.

Searching for planets around giant stars also is a clever way to learn about the formation of planets around stars more massive than our Sun. Because massive stars are so hot when they are in the phase of life of our Sun, astronomers have not been able to detect enough of their spectral lines to use the Doppler-spectroscopy method of finding planets. However, these stars become cooler as they evolve into giants, at which point the spectral-line observations needed for Doppler detection of planets become possible. "We want to know how often do planets form around stars that were more massive than our Sun," Wolszczan said. "Obviously, the more solar systems around red giants we discover and study, the better chance we have to really understand the big picture of planet formation."

Another reason astronomers are trying to discover planets around different kinds of stars at different stages of stellar evolution is to find out how different kinds of planetary systems change when their stars become red giants and how they ultimately end their lives as burnt-out, shrunken white-dwarfs.

"We really are at the very beginning of this effort and it is going to take time to get a consistent picture of planetary formation and evolution," Wolszczan says. "The more we learn, the greater the chance will be that sooner or later we will discover how ordinary or extraordinary is our home -- the Earth's solar system."

SOURCE: SPACEFLIGHTNOW.COM

[neilep (OP)]

An Early Ape Shows Its Hand (8/8/07)

Fossils often have provided important insights into the evolution of humans and our ancestors. Even small fossils, such as bones from the hand or foot can tell us much about our ancestor’s and their behavior. Such may be the case with an ape that lived more than nine million years ago.

A study published in the latest journal issue of Proceedings of the Royal Society B: Biological Sciencesreports on the structure of the hand of Hispanopithecus, a critically important fossil from an ape that lived during the late Miocene of Spain. While the authors ponder that the fossil may be from a direct ancestor of living great apes (especially the orangutan), Dr. C. Owen Lovejoy, Kent State University Professor of Anthropology, suggests another possibility in his comment on the article published in the same issue.

A preeminent biological anthropologist in the study of human origins, Lovejoy suggests that the fossil may belong to an extinct ape with its own unique locomotor behavior—a special adaptation and unique form of locomtion that left no modern descendants.

In 2007, Lovejoy was elected to membership in the prestigious National Academy of Sciences for his excellence in original scientific research.

SOURCE:EUREKALERT.ORG

[neilep (OP)]

Beyond Mesopotamia:

 A radical new view of human civilization reported in Science
Many urban centers crossed arc of Middle Asia 5,000 years ago

A radically expanded view of the origin of civilization, extending far beyond Mesopotamia, is reported by journalist Andrew Lawler in the 3 August issue of Science.

Mesopotamia is widely believed to be the cradle of civilization, but a growing body of evidence suggests that in addition to Mesopotamia, many civilized urban areas existed at the same time – about 5,000 years ago – in an arc that extended from Mesopotamia east for thousands of kilometers across to the areas of modern India and Pakistan, according to Lawler.

“While Mesopotamia is still the cradle of civilization in the sense that urban evolution began there,” Lawler said, “we now know that the area between Mesopotamia and India spawned a host of cities and cultures between 3000 B.C.E. and 2000 B.C.E.”

Evidence of shared trade, iconography and other culture from digs in remote areas across this arc were presented last month at a meeting in Ravenna, Italy of the International Association for the Study of Early Civilizations in the Middle Asian Intercultural Space. The meeting was the first time that many archaeologists from more than a dozen countries gathered to discuss the fresh finds that point to this new view of civilization’s start. Science’s Lawler was the only journalist present.

Archaeologists shared findings from dozens of urban centers of approximately the same age that existed between Mesopotamia and the Indus River valley in modern day India and Pakistan. The researchers are just starting to sketch out this new landscape, but it’s becoming clear that these centers traded goods and could have shared technology and architecture. Recovered artifacts such as beads, shells, vessels, seals and game boards show that a network linked these civilizations.

Researchers have also found hints, such as similar ceremonial platforms, that these cultures interacted and even learned from one another. A new excavation near Jiroft in southeastern Iran, for example, has unearthed tablets with an unknown writing system. This controversial find highlights the complexity of the cultures in an area long considered a backwater, Lawler explained.

These urban centers are away from the river valleys that archaeologists have traditionally focused on, according to Lawler. Archaeologists now have access to more remote locations and are expanding their studies.

SOURCE:EUREKALERT.ORG

[neilep (OP)]

What makes Mars magnetic?
EUROPEAN SCIENCE FOUNDATION NEWS RELEASE
Posted: August 22, 2007

*This'll interest some geologists, I think one or two may frequent the site*

Earth's surface is a very active place; its plates are forever jiggling around, rearranging themselves into new configurations. Continents collide and mountains arise, oceans slide beneath continents and volcanoes spew. As far as we know Earth's restless surface is unique to the planets in our solar system. So what is it that keeps Earth's plates oiled and on the move?

Scientists think that the secret lies beneath the crust, in the slippery asthenosphere. In order for the mantle to convect and the plates to slide they require a lubricated layer. On Mars this lubrication has long since dried up, but on Earth the plates can still glide around with ease.

If you could pick up a rock from the surface of Mars, then the chances are it would be magnetic. And yet, Mars doesn't have a magnetic field coming from its core. These rocks are clinging to the signal of an ancient magnetic field, dating back billions of years, to the times when Mars had a magnetic field like Earth's.

So how have these rocks hung onto their magnetic directions and what do they tell us about Mars? Strangely, the answer to these questions might be sitting here on Earth.

Most continental rocks on Earth align their magnetic moments with the current magnetic field - they are said to have -induced' magnetism. "I consider induced rocks to have -Alzheimers'. These are the rocks that forgot where they were born and how to get home," explains Suzanne McEnroe from the Geological Survey of Norway at a European Science Foundation, EuroMinScI conference near Nice, France this year.

However, not all of Earth's continental rocks have an induced magnetization. Some rocks stubbornly refuse to swing with the latest magnetic field, and instead keep hold of the direction they were born with. These rocks are said to have a remanent magnetization.

McEnroe and her colleagues have been studying some of Earth's strongest and oldest remanent magnetic rocks, to find out why they have such good memories. Understanding these rocks may give us clues as to what kind of rocks lie on Mars.

One of their research projects (in cooperation with Phil Schmidt and David Clark at CSIRO, Australia and just published in the Journal of Geophysical Research) is on the Peculiar Knob Formation in South Australia. These rocks are around 1 billion years old and have a strong magnetic remanence, more than 30 times larger than typically found in basaltic rocks.

"This particular research evolved from looking for an economic mineral deposit," says McEnroe. The mining company had assumed that the rocks in this strongly magnetic area were holding an induced magnetic field and that there would be magnetite buried down below. However, they were puzzled when a different mineral - hematite, came out of the drill core. Had they missed their target, or were their assumptions wrong?

By studying the samples under a powerful microscope and modelling their magnetic properties, McEnroe was able to show that the hematite was responsible for the strong magnetic field and that it was holding a remanent field from around 1 billion years ago. "We could see that the hematite contained small intergrowths that carried the magnetism," says McEnroe, who presented her findings at the 1st EuroMinScI Conference near Nice, France in March this year.

And it turns out that the microstructure of the rock is the key to whether it can hold a remanent magnetization or not. Together with Richard Harrison, a mineral physicist at Cambridge University, UK, and Peter Robinson at NGU, McEnroe has been studying strong remanent magnetic rocks from a variety of places including Scandinavia and the USA.

A study on nearly billion-year-old rocks in Norway showed a remanent magnetic anomaly comparable in scale to those observed on Mars.  The remanent magnetic anomaly dominates the local magnetic field to such a degree that more than half the Earth's field is cancelled.  It is nearly impossible to use a compass in the area, which cannot point correctly north because of the strong remanent magnetization in the rocks.

What they have found is that rocks containing nanometre scale intergrowths of ilmenite and hematite are better able to cling onto their original magnetization than those without such fine-scale features. "Placing a nanoparticle of ilmenite into the hematite host creates a strong and stable magnetic signal that can survive large changes in temperature and magnetic field over billions of years," explains Harrison.

So can this tell us anything about the rocks on Mars? "These rocks are good analogues for the magnetic rocks we see on Mars because of their strong magnetism and the length of time they have retained this memory," says McEnroe. Certainly this nano-scale microstructure is a plausible candidate for the magnetic rocks on Mars.

However, the rocks on Earth can't answer all our questions. "There is not going to be one mineral or one tectonic setting on Mars. There are going to be different reasons that enhance the signature in different places," says McEnroe. The only way to definitively answer the question is to go and pick up some rocks from Mars. 


SOURCE:SPACEFLIGHTNOW.COM

[neilep (OP)]

Astronomers spot brightest galaxies in distant universe
CENTER FOR ASTROPHYSICS NEWS RELEASE
Posted: August 22, 2007

CAMBRIDGE, MA - By combining the capabilities of several telescopes, astronomers have spotted extremely bright galaxies hiding in the distant, young universe. The newfound galaxies are intrinsically bright due to their large rate of star formation-1000 times greater than the Milky Way. However, much of that light is hidden by surrounding dust and gas, leaking out only in the infrared.

The galaxies are located about 12 billion light-years away, and existed when the universe was less than 2 billion years old. They are the most luminous and massive galaxies seen at that great distance. Smaller, dimmer galaxies were much more common in the early universe because it takes time for galaxies to form and grow.

"It's a real surprise to find galaxies that massive and luminous existing so early in the universe," said astronomer Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics (CfA). "We are witnessing the moment when the most massive galaxies in the universe were forming most of their stars in their early youth."

"It's tough to explain how such bright, massive, dusty galaxies formed so early in the lifetime of the universe," added Harvard graduate student Josh Younger.

The hide-and-seek galaxies initially were spotted with the AzTEC imaging camera on the James Clerk Maxwell Telescope. The camera, developed by a team led by Grant Wilson and Min Yun of the University of Massachusetts at Amherst, discovered several hundred previously unseen galaxies that were bright at millimeter and submillimeter wavelengths.

A team of astronomers made follow-up observations of the seven brightest galaxies in an area of the sky studied by the Cosmic Evolution Survey (COSMOS). The Smithsonian's Submillimeter Array pinpointed the exact location of each galaxy, allowing the team to confirm that the source was a single galaxy and not a blend of several fainter galaxies.

Once precise locations were known, additional observations were made with the Hubble Space Telescope, the Spitzer Space Telescope, and the Very Large Array of radio telescopes. Even Hubble's powerful vision did not detect the galaxies, confirming that they are shrouded in dust that blocks visible light. Spitzer could penetrate the dust and detect the stars directly. The Very Large Array detected only the two closest galaxies.

By combining these measurements, the astronomers showed that five of the seven AzTEC galaxies are located at redshifts greater than 3, which corresponds to a distance of 12 billion light-years.

"These results suggest that the brightest submillimeter galaxies may be the most distant," said Fazio.

The galaxies' large infrared brightness indicates that they are forming new stars rapidly, probably due to collisions and mergers.

"The source of the infrared radiation seems to be very compact, which suggests that they are colliding galaxies that may eventually evolve into quasars," said Younger.

In the future, the astronomers plan to image more sources of submillimeter radiation in different cosmic environments, to try to better understand the population.

"We also plan to use the most extended configuration of the SMA to zoom in and try to resolve these objects, and really narrow down the source of their extreme infrared luminosity," added Younger.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe

SOURCE:SPACEFLIGHTNOW.COM

[paul.fr]

We have developed several devices for positioning organic molecules, molecular aggregates, cells, and single-cell organisms onto solid supports. These printers can create stable, functional protein arrays using an inexpensive technology. The cell printer allows us to create cell libraries as well as cellular assemblies that mimic their respective position in organs. The printers are derived from commercially available ink-jet printers that are modified to dispense protein or cell solutions instead of ink. We describe here the modifications to the print heads, and the printer hardware and software that enabled us to adapt the ink-jet printers for the manufacture of cell and protein arrays. The printers have the advantage of being fully automated and computer controlled, and allow for the high-throughput manufacture of protein and cell arrays.

http://www.citeulike.org/user/rodney/article/1567867

bubble jet printers are also being used to make batteries that are...er, paper thin.

[neilep (OP)]

Gamma-ray lighthouse at the edge of our universe
EUROPEAN SPACE AGENCY NEWS RELEASE


There is a gamma-ray lighthouse shining from the edge of our universe. Astronomers have discovered it using the European Space Agency's orbiting gamma-ray observatory, Integral. Now, they must work hard to understand it.

The object, known only by its catalogue name IGR J22517+2218, was discovered this year, but its nature was unknown. This is not an unusual situation. Around 30% of the sources discovered by Integral remain unidentified so far. All astronomers know for certain, is that there are celestial sources out there, pumping gamma rays into space. However, the identification of the sources with individual celestial objects will have to wait for more detailed observations in other wavelengths.

In fact, this was the case for IGR J22517+2218. It came as a surprise when NASA's Swift satellite recorded the object in X-rays, giving its position within much more precision than can be achieved in gamma-rays. IGR J22517+2218 was identified with the already known active galaxy MG3 J225155+2217. This galaxy is so distant that it is the furthest celestial object ever to be recorded by Integral.

All active galaxies are powered by supermassive black holes. These celestial monsters contain between a million and several thousand million times the mass of the Sun.

They generate a gravitational field so large that they swallow any matter passing nearby, releasing enormous amounts of energy in the process. In the case of IGR J22517+2218, the Integral observations show that it is a gargantuan powerhouse, throwing out stupendous quantities of gamma rays.

"It is gobbling up an entire solar system every few days and hurling the energy out in gamma-rays," says Loredana Bassani, IASF-Bologna/INAF, Italy, who together with colleagues has investigated this distant galaxy.

The Integral observations show that the galaxy is one of a special kind of active galaxy, known as a blazar. These are the most energetic of the active galaxies. However, the Integral data does show some curiosities.

"This is a very peculiar object. We have been able to classify it as a blazar but it has some strange characteristics," says Bassani.

Blazars tend to have two major peaks of emission. In objects similar to IGR J22517+2218, one peak occurs in infrared wavelengths and is produced by the radiation given off by electrons spiralling around the magnetic field lines. The other peak occurs at high-energy gamma-ray wavelengths and is produced by those same electrons colliding with photons of light.

In the case of IGR J22517+2218, the object appears to have only one peak. This occurs in neither of the conventional wavelength ranges but, in fact, in the low-energy gamma-ray band instead. Either the infrared peak has been moved up in energy, or the high-energy gamma-ray peak has been moved down.

Either way, when the team can work out what this means, it will doubtlessly tell them a lot about active galaxies, and blazars in particular. "Whatever we discover, this object will stretch our understanding of the blazars," says Bassani.

The team hope to continue observing this object at all wavelengths in an effort to build up a full picture of the radiation given out by this celestial object. In this way, they will be able to piece together the manner in which the supermassive black hole at the heart of IGR J22517+2218 is devouring its surroundings.   


Source: SPACEFLIGHTNOW.COM

[neilep (OP)]

Patients should ask surgeons about using honey to heal wounds

Surgeons are being advised to consider the supermarket as well as the drugs cupboard when it comes to effective wound healing, according to a research review published in the October issue of IJCP, the International Journal of Clinical Practice.

And patients who’ve undergone surgery should ask their doctors whether they should apply honey to their wounds to speed up healing and reduce infection.

“Honey is one of the oldest foods in existence and was an ancient remedy for wound healing” explains lead author Dr Fasal Rauf Khan from North West Wales NHS Trust in Bangor. “It was found in the tomb of King Tutankhamun and was still edible as it never spoils.”

Honey is enjoying a revival as more reports of its effectiveness are published, he adds.

“Researchers started to document the wound healing properties of honey in the early 20th century, but the introduction of antibiotics in 1940 temporarily halted its use.

“Now concerns about antibiotic resistance, and a renewed interest in natural remedies, has prompted a resurgence in the antimicrobial and wound healing properties of honey.

“Honey has a number of properties that make it effective against bacterial growth, including its high sugar content, low moisture content, gluconic acid – which creates an acidic environment – and hydrogen peroxide. It has also been shown to reduce inflammation and swelling.”

Researchers have also reported that applying honey can be used to reduce amputation rates among diabetes patients.

Stressing that patients should always check with their surgeon before applying any substance to post-operative wounds, Dr Khan adds that studies have found that honey offers a number of benefits.

“It can be used to sterilise infected wounds, speed up healing and impede tumours, particularly in keyhole surgery.”

Studies have suggested that honey should be applied at regular intervals, from hourly to twice daily and that wounds can become sterile in three to 10 days.

“The research suggests that honey seems to be especially indicated when wounds become infected or fail to close or heal” says Dr Khan. “It is probably even more useful for healing the wounds left by laparoscopic surgery to remove cancers.”

18 studies covering more than 60 years were included in the review. The authors also looked at other substances used for wound healing, including maggots, which were also commonly used before the introduction of antibiotics and are enjoying a revival.

The team also discovered an ancient manuscript that used wine dregs, juniper prunes and beer, but point out that that has not been tried and tested in recent years!

“Our research suggests that surgeons should seriously consider using honey for post-operative wounds and offer this to patients” concludes Dr Khan. “We would also encourage patients to ask about honey as an option, but stress that they should always follow their surgeon’s advice and not try any home remedies.”

SOURCE: EUREKALERT.ORG

[neilep (OP)]

Dwarf galaxies need dark matter too, U-M astronomers say

ANN ARBOR, Mich.—Stars in dwarf spheroidal galaxies behave in a way that suggests the galaxies are utterly dominated by dark matter, University of Michigan astronomers have found.

Astronomy professor Mario Mateo and post-doctoral researcher Matthew Walker measured the velocity of 6,804 stars in seven dwarf satellite galaxies of the Milky Way: Carina, Draco, Fornax, Leo I, Leo II, Sculptor and Sextans. They found that, contrary to what Newton's law of gravity predicts, stars in these galaxies do not move slower the farther they are from their galaxy's core.

"These galaxies show a problem right from the center," Mateo said. "The velocity doesn't get smaller. It just stays the same, which is eerie."

Astronomers already know stars in spiral galaxies behave in a similar way. This research dramatically increases the available information about smaller galaxies, making it possible to confirm that the distribution of light and stars in them is not the same as the distribution of mass.

"We have more than doubled the amount of data having to do with these galaxies, and that allows us to study them in an unprecedented manner. Our research shows that dwarf galaxies are utterly dominated by dark matter, so long as Newtonian gravity adequately describes these systems," Walker said. Walker received his doctorate from U-M earlier this year and currently has a post-doctoral position at the University of Cambridge in the United Kingdom.

Dark matter is a substance astronomers have not directly observed, but they deduce it exists because they detect its gravitational effects on visible matter. Based on these measurements, the prevailing theory in astronomy and cosmology is that the visible parts of the universe make up only a fraction of its total matter and energy.

The planet Neptune was once "dark matter," Mateo said. Before the term was even coined, astronomers predicted its existence based on an anomaly in the orbit of Neptune's neighbor Uranus. They knew just where to look for Neptune.

For the past quarter century, astronomers have been looking for the Neptune of the universe, so to speak. Dark matter could take the form of dwarf stars and planets, elementary particles including neutrinos, or hypothetical and as-yet undetected particles that don't interact with visible light or other parts of the electromagnetic spectrum.

Dark matter is believed to hold galaxies together. The gravitational force of the visible matter is not considered strong enough to prevent stars from escaping. Other theories exist to explain these discrepancies, though. For example, Modified Newtonian Dynamics, Mateo said, proposes that gravitational forces become stronger when accelerations are very weak. While their results align with current dark matter models, Mateo and Walker say they also bolster this less-popular explanation.

"These dwarf galaxies are not much to look at," Mateo continued, "but they may really alter our fundamental views on the nature of dark matter and, perhaps, even gravity."

Walker will present a paper on these findings on Oct. 30 at the Magellan Science Meeting in Cambridge, Mass. The paper he will present is Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies. It was published in the Sept. 20 edition of Astrophysical Journal Letters.

SOURCE: University of Michigan News Service http://www.ns.umich.edu

[neilep (OP)]

Scientist brings 50 million year old spider 'back to life'

A 50-million-year-old fossilised spider has been brought back to life in stunning 3D by a scientist at The University of Manchester.

In a paper published in the latest issue of the Zootaxa journal, Dr David Penney and co-authors from Ghent University in Belgium report on the use of a technique called ‘Very High Resolution X-Ray Computed Tomography’ (VHR-CT) to ‘digitally dissect’ tiny fossils and reveal the preservation of internal organs.

Dr Penney, from The School of Earth, Atmospheric and Environmental Sciences (SEAES), specialises in studying spiders trapped and preserved in amber tens of millions of years ago.

The male spider studied in his latest paper is a new species named Cenotextricella simoni. It is around 53-million years old and was found preserved in amber in an area of France known as the Paris Basin.

This is the first time the VHR-CT technique has been used to digitally dissect a fossil in amber – and Dr Penney says it has the potential to ‘revolutionise’ their study.

The VHR-CT technique was originally developed for medical diagnostic purposes.

Dr Penney said: “This technique essentially generates full 3D reconstructions of minute fossils and permits digital dissection of the specimen to reveal the preservation of internal organs.

“Up until recently the only place to do such scans was at The University of Texas, although they never achieved results like these.

“My colleagues in the department of Subatomic and Radiation Physics at Ghent University in Belgium have significantly increased the resolution of the technology, bringing some quite amazing results.

“This is definitely the way forward for the study of amber fossils.

“Amber provides a unique window into past forest ecosystems. It retains an incredible amount of information, not just about the spiders themselves, but also about the environment in which they lived.”

Dr Penney is currently spending an indefinite period in the African jungle in a ‘living laboratory' studying spiders.

Earlier this year, a species of spider which dates back more than 20 million years was named after Dr Penney. The amber-encased spider which was discovered deep in a Mexican mine is thought to have lived long before the first humans.

It was found by a Mexican researcher who earned the right to name the species and he chose the name ‘Episinus penneyi’ in honour of his former colleague.

SOURCE: www.eurekalert.org

[neilep (OP)]

A new window on the universe
UWM physicists involved in international project to scour space for gravitational waves

UWM physicists who are working on the international LIGO project are (clockwise from left) Xavier Siemens, Alan Wiseman, Patrick Brady and Jolien Creighton. All four faculty members came to UWM...
Click here for more information.

Using new tools to look at the universe, says Patrick Brady, often has led to discoveries that change the course of science. History is full of examples.

“Galileo was the first person to use the telescope to view the cosmos,” says Brady, a UWM professor of physics. “His observations with the new technology led to the discovery of moons orbiting Jupiter and lent support to the heliocentric model of the solar system.”

Just such an opportunity exists today with a unique observatory that is scanning the skies, searching for one of Einstein’s greatest predictions – gravitational waves.

Gravitational waves are produced when massive objects in space move violently. The waves carry the imprint of the events that cause them. Scientists already have indirect evidence that gravitational waves exist, but have not directly detected them.

UWM researchers, backed by considerable funding from the National Science Foundation, are taking a leadership role in the quest.

It is an epic undertaking involving about 500 scientists worldwide, including Brady and other members of UWM’s Center for Cosmology and Gravitation: associate professors Alan Wiseman and Jolien Creighton, and assistant professor Xavier Siemens.

Two UWM adjunct physicists, who work at the Max Planck Institute in Germany, also are involved – former UWM professor Bruce Allen and scientist Maria Alessandra Papa.

“It’s an unimaginable opportunity to be on the forefront of scientific discovery,” says Creighton.

The Laser Interferometer Gravitational-wave Observatory, or LIGO, consists of detectors at two U.S. sites managed by the California Institute of Technology (Caltech) and Massachusetts Institute of Technology (MIT).

UWM’s physicists are analyzing the data generated by the LIGO facilities.

The project is supported with a sizable investment of grant money from both federal and UWM sources.

Last year, UWM’s LIGO group brought in $3 million in grant funding. Since 1999, UWM has received more than $9 million for the project, with much of it going toward a supercomputer called Nemo that operates unobtrusively on the second floor of the Physics Building.

Stretching and squeezing

The LIGO observatories use lasers to accurately monitor the distance between a central station and mirrors suspended three miles away along perpendicular arms. When a gravitational wave, a traveling ripple in space-time, passes by, the mirror in one arm will move closer to the central station, while the other mirror will move away.

The change in distance caused by stretching and squeezing is what LIGO is designed to measure, says Wiseman.

Those changes will be inconceivably tiny. LIGO can record distortions at a scale so small, it is comparable in distance to a thousandth of the size of an atomic nucleus.

LIGO records a series of numbers – lots of them – and feeds them to several supercomputer clusters around the country, including UWM’s Nemo cluster.

Think of a modern hard disk on a desktop computer, which stores about 100 gigabytes. LIGO fills up about 10 of those at Nemo in a single day, says Brady.

The computer’s job is to sort out the numerical patterns representing gravitational waves buried in ambient noise produced by lots of other vibrations – from internal vibrations of the equipment itself, to magnetic fluctuations from lightning storms, to seismic vibrations from trains rolling along the tracks a few miles from the observatory, or from earthquakes on the other side of the world.

“There are thousands or even millions of different signals that could be emitted from space,” says Wiseman. “So you have to take each segment of data individually. That turns out to be a formidable computational problem.”

Nemo performs many billions of calculations per second in its search for these signals.

Space sounds

The strings of numbers from LIGO are like tracks on a compact disk, says Brady. That means, once detected, gravitational-wave signals can be converted into sound.

In fact, scientists have already simulated, based on mathematical predictions, what certain events in space will sound like.

When two black holes are merging, for example, you might expect to hear a “chirp” that represents the spiraling together of the black holes just before they collide. “The spiral can go on for tens of thousands of years,” says Brady. “The sound is the identifying signal of the last few seconds of the process!”

Those analyzing the data from space could actually listen to the data. Instead, scientists look for the signals using computers like Nemo.

To augment the computing capacity, UWM is hosting a way for anyone with a computer and a high-speed Internet connection to join the astrophysical treasure hunt. Called “Einstein@Home, the program borrows computer power available when participants are not using it, and pool those resources to aid in filtering the massive amounts of data from LIGO.

Possible secrets

Scientists concede that the current LIGO facilities will need to be improved to increase the chances of detecting gravitational waves. More NSF funding to do that is requested in the 2009 U.S. budget currently winding its way through the approval process.

For now, the best hope is to detect events relatively close to Earth.

So what is the likelihood of success"

“The events we are looking for may only happen once every million years in our galaxy,” says Wiseman, “but if your instrument is sensitive enough to see such events in, say, one million galaxies, then the probability of detecting something is much larger.”

Gravitational waves may hold secrets to the nature of black holes, the unknown properties of nuclear material, and maybe even how the universe began.

“We’ve only been able to find out about the universe since it became cool,” says Siemens. “But with gravitational waves, we’ll see the universe when it was much younger – and hotter.”

But then again, scientists don’t really know.

“I think we’re in for a surprise,” says Siemens. “We have all these ideas about what we think we will find, but it could be something completely different.”

[neilep (OP)]

Saturn's rings may be old as solar system, Cassini shows
UNIVERSITY OF COLORADO NEWS RELEASE
Posted: December 12, 2007

New observations by NASA's Cassini spacecraft indicate the rings of Saturn, once thought to have formed during the age of the dinosaurs, instead may have been created roughly 4.5 billion years ago when the solar system was still under construction.



 
Professor Larry Esposito, principal investigator for Cassini's Ultraviolet Imaging Spectrograph at CU-Boulder, said data from NASA's Voyager spacecraft in the 1970s and later NASA's Hubble Space Telescope had led scientists to believe Saturn's rings were relatively youthful and likely created by a comet that shattered a large moon, perhaps 100 million years ago.

But ring features seen by instruments on Cassini -- which arrived at Saturn in 2004 -- indicate the rings were not formed by a single cataclysmic event, he said. The ages of the different rings appear to vary significantly and the ring material is continually being recycled, Esposito said.

"The evidence is consistent with the picture that Saturn has had rings all through its history," said Esposito of CU-Boulder's Laboratory for Atmospheric and Space Physics. "We see extensive, rapid recycling of ring material, in which moons are continually shattered into ring particles, which then gather together and re-form moons."

Esposito and CU-Boulder colleague Miodrag Sremcevic presented their findings today in a news briefing at the fall meeting of the American Geophysical Union held Dec. 10 to Dec. 14 in San Francisco.

"We have discovered that the rings were probably not created just yesterday in cosmic time, and in this scenario it is not just luck that we are seeing planetary rings now," said Esposito. "They probably were always around but continually changing, and they will be around for many billions of years."

Scientists had previously believed rings as old as Saturn itself should be darker due to ongoing pollution by the "infall" of meteoric dust, leaving telltale spectral signatures, Esposito said. But the new Cassini observations indicate the churning mass of ice and rock within Saturn's gigantic ring system is likely much larger than previously estimated, helping to explain why the rings appear relatively bright to ground-based telescopes and spacecraft.

"The more mass there is in the rings, the more raw material there is for recycling, which essentially spreads this cosmic pollution around," he said. "If this pollution is being shared by a much larger volume of ring material, it becomes diluted and helps explain why the rings appear brighter and more pristine than we would have expected."

Esposito, who discovered Saturn's faint F ring in 1979 using data from NASA's Pioneer 11 spacecraft, said an upcoming paper by him and colleagues in the journal Icarus supports the theory that Saturn's ring material is being continually recycled. Observing the flickering of starlight passing through the rings in a process known as stellar occultation, the researchers discovered 13 objects in the F ring ranging in size from 30 yards to six miles across.

Since most of the objects were translucent -- indicating at least some starlight was passing through them -- the researchers concluded they probably are temporary clumps of icy boulders that are continually collecting and disbanding due to the competing processes of shattering and coming together again. The team tagged the clumpy moonlets with cat names like "Mittens" and "Fluffy" because they appear to come and go unexpectedly over time and have multiple lives, said Esposito.

Esposito stressed that in the future Saturn's rings won't be the same we see today, likening them to great cities around the world like San Francisco, Berlin or Beijing. "While the cities themselves will go on for centuries or millennia, the faces of people on the streets will always be changing due to continual birth and aging of new citizens."

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

SOURCE: SPACFLIGHTNOW.ORG

[neilep (OP)]

Are humans evolving faster?

Findings suggest we are becoming more different, not alike
Researchers discovered genetic evidence that human evolution is speeding up – and has not halted or proceeded at a constant rate, as had been thought – indicating that humans on different continents are becoming increasingly different.

“We used a new genomic technology to show that humans are evolving rapidly, and that the pace of change has accelerated a lot in the last 40,000 years, especially since the end of the Ice Age roughly 10,000 years ago,” says research team leader Henry Harpending, a distinguished professor of anthropology at the University of Utah.

Harpending says there are provocative implications from the study, published online Monday, Dec. 10 in the journal Proceedings of the National Academy of Sciences:

-- “We aren’t the same as people even 1,000 or 2,000 years ago,” he says, which may explain, for example, part of the difference between Viking invaders and their peaceful Swedish descendants. “The dogma has been these are cultural fluctuations, but almost any temperament trait you look at is under strong genetic influence.”

-- “Human races are evolving away from each other,” Harpending says. “Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity.” He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, “and there has not been much flow of genes between the regions since then.”

“Our study denies the widely held assumption or belief that modern humans [those who widely adopted advanced tools and art] appeared 40,000 years ago, have not changed since and that we are all pretty much the same. We show that humans are changing relatively rapidly on a scale of centuries to millennia, and that these changes are different in different continental groups.”

The increase in human population from millions to billions in the last 10,000 years accelerated the rate of evolution because “we were in new environments to which we needed to adapt,” Harpending adds. “And with a larger population, more mutations occurred.”

Study co-author Gregory M. Cochran says: “History looks more and more like a science fiction novel in which mutants repeatedly arose and displaced normal humans – sometimes quietly, by surviving starvation and disease better, sometimes as a conquering horde. And we are those mutants.”

Harpending conducted the study with Cochran, a New Mexico physicist, self-taught evolutionary biologist and adjunct professor of anthropology at the University of Utah; anthropologist John Hawks, a former Utah postdoctoral researcher now at the University of Wisconsin, Madison; geneticist Eric Wang of Affymetrix, Inc. in Santa Clara, Calif.; and biochemist Robert Moyzis of the University of California, Irvine.

No Justification for Discrimination

The new study comes from two of the same University of Utah scientists – Harpending and Cochran – who created a stir in 2005 when they published a study arguing that above-average intelligence in Ashkenazi Jews – those of northern European heritage – resulted from natural selection in medieval Europe, where they were pressured into jobs as financiers, traders, managers and tax collectors. Those who were smarter succeeded, grew wealthy and had bigger families to pass on their genes. Yet that intelligence also is linked to genetic diseases such as Tay-Sachs and Gaucher in Jews.

That study and others dealing with genetic differences among humans – whose DNA is more than 99 percent identical – generated fears such research will undermine the principle of human equality and justify racism and discrimination. Other critics question the quality of the science and argue culture plays a bigger role than genetics.

Harpending says genetic differences among different human populations “cannot be used to justify discrimination. Rights in the Constitution aren’t predicated on utter equality. People have rights and should have opportunities whatever their group.”

Analyzing SNPs of Evolutionary Acceleration

The study looked for genetic evidence of natural selection – the evolution of favorable gene mutations – during the past 80,000 years by analyzing DNA from 270 individuals in the International HapMap Project, an effort to identify variations in human genes that cause disease and can serve as targets for new medicines.

The new study looked specifically at genetic variations called “single nucleotide polymorphisms,” or SNPs (pronounced “snips”) which are single-point mutations in chromosomes that are spreading through a significant proportion of the population.

Imagine walking along two chromosomes – the same chromosome from two different people. Chromosomes are made of DNA, a twisting, ladder-like structure in which each rung is made of a “base pair” of amino acids, either G-C or A-T. Harpending says that about every 1,000 base pairs, there will be a difference between the two chromosomes. That is known as a SNP.

Data examined in the study included 3.9 million SNPs from the 270 people in four populations: Han Chinese, Japanese, Africa’s Yoruba tribe and northern Europeans, represented largely by data from Utah Mormons, says Harpending.

Over time, chromosomes randomly break and recombine to create new versions or variants of the chromosome. “If a favorable mutation appears, then the number of copies of that chromosome will increase rapidly” in the population because people with the mutation are more likely to survive and reproduce, Harpending says.

“And if it increases rapidly, it becomes common in the population in a short time,” he adds.

The researchers took advantage of that to determine if genes on chromosomes had evolved recently. Humans have 23 pairs of chromosomes, with each parent providing one copy of each of the 23. If the same chromosome from numerous people has a segment with an identical pattern of SNPs, that indicates that segment of the chromosome has not broken up and recombined recently.

That means a gene on that segment of chromosome must have evolved recently and fast; if it had evolved long ago, the chromosome would have broken and recombined.

Harpending and colleagues used a computer to scan the data for chromosome segments that had identical SNP patterns and thus had not broken and recombined, meaning they evolved recently. They also calculated how recently the genes evolved.

A key finding: 7 percent of human genes are undergoing rapid, recent evolution.

The researchers built a case that human evolution has accelerated by comparing genetic data with what the data should look like if human evolution had been constant:


The study found much more genetic diversity in the SNPs than would be expected if human evolution had remained constant.


If the rate at which new genes evolve in Africans was extrapolated back to 6 million years ago when humans and chimpanzees diverged, the genetic difference between modern chimps and humans would be 160 times greater than it really is. So the evolution rate of Africans represents a recent speedup in evolution.


If evolution had been fast and constant for a long time, there should be many recently evolved genes that have spread to everyone. Yet, the study revealed many genes still becoming more frequent in the population, indicating a recent evolutionary speedup.

Next, the researchers examined the history of human population size on each continent. They found that mutation patterns seen in the genome data were consistent with the hypothesis that evolution is faster in larger populations.

Evolutionary Change and Human History: Got Milk?

“Rapid population growth has been coupled with vast changes in cultures and ecology, creating new opportunities for adaptation,” the study says. “The past 10,000 years have seen rapid skeletal and dental evolution in human populations, as well as the appearance of many new genetic responses to diet and disease.”

The researchers note that human migrations into new Eurasian environments created selective pressures favoring less skin pigmentation (so more sunlight could be absorbed by skin to make vitamin D), adaptation to cold weather and dietary changes.

Because human population grew from several million at the end of the Ice Age to 6 billion now, more favored new genes have emerged and evolution has speeded up, both globally and among continental groups of people, Harpending says.

"We have to understand genetic change in order to understand history,” he adds.

For example, in China and most of Africa, few people can digest fresh milk into adulthood. Yet in Sweden and Denmark, the gene that makes the milk-digesting enzyme lactase remains active, so “almost everyone can drink fresh milk,” explaining why dairying is more common in Europe than in the Mediterranean and Africa, Harpending says.

He now is studying if the mutation that allowed lactose tolerance spurred some of history’s great population expansions, including when speakers of Indo-European languages settled all the way from northwest India and central Asia through Persia and across Europe 4,000 to 5,000 years ago. He suspects milk drinking gave lactose-tolerant Indo-European speakers more energy, allowing them to conquer a large area.

But Harpending believes the speedup in human evolution “is a temporary state of affairs because of our new environments since the dispersal of modern humans 40,000 years ago and especially since the invention of agriculture 12,000 years ago. That changed our diet and changed our social systems. If you suddenly take hunter-gatherers and give them a diet of corn, they frequently get diabetes. We’re still adapting to that. Several new genes we see spreading through the population are involved with helping us prosper with high-carbohydrate diet.”





SOURCE : University of Utah Public Relations

www.unews.utah.edu

Via EUYREALERT.ORG