May 19, 2010
A new infrared image from NASA’s Wide-field Infrared Survey Explorer, or WISE, showcases the Tadpole nebula, a star-forming hub in the Auriga constellation about 12,000 light-years from Earth. As WISE scanned the sky, capturing this mosaic of stitched-together frames, it happened to catch an asteroid in our solar system passing by. The asteroid, called 1719 Jens, left tracks across the image, seen as a line of yellow-green dots in the boxes near center. A second asteroid, called 1992 UZ5, was also observed cruising by, as highlighted in the boxes near the upper left (the larger boxes are blown-up versions of the smaller ones).
But that’s not all that WISE caught in this busy image — two satellites orbiting above WISE (highlighted in the ovals) streak through the image, appearing as faint green trails. The apparent motion of asteroids is slower than satellites because asteroids are much more distant, and thus appear as dots that move from one WISE frame to the next, rather than streaks in a single frame.
This Tadpole region is chock full of stars as young as only a million years old — infants in stellar terms — and masses over 10 times that of our sun. It is called the Tadpole nebula because the masses of hot, young stars are blasting out ultraviolet radiation that has etched the gas into two tadpole-shaped pillars, called Sim 129 and Sim 130. These “tadpoles” appear as the yellow squiggles near the center of the frame. The knotted regions at their heads are likely to contain new young stars. WISE’s infrared vision is helping to ferret out hidden stars such as these.
The 1719 Jens asteroid, discovered in 1950, orbits in the main asteroid belt between Mars and Jupiter. The space rock, which has a diameter of 19 kilometers (12 miles), rotates every 5.9 hours and orbits the sun every 4.3 years.
Twenty-five frames of the region, taken at all four of the wavelengths detected by WISE, were combined into this one image. The space telescope caught 1719 Jens in 11 successive frames. Infrared light of 3.4 microns is color-coded blue: 4.6-micron light is cyan; 12-micron-light is green; and 22-micron light is red.
WISE is an all-sky survey, snapping pictures of the whole sky, including everything from asteroids to stars to powerful, distant galaxies.
JPL manages WISE for NASA’s Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA’s Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.
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May 18, 2010
After billions of years of twinkling and shining, some stars in the heavens appear to “dance” as they wind down. Maybe not like Elvis or Michael Jackson, but they definitely have a rhythmic beat, and some may even spin like a top.
For the next two weeks, the Whole Earth Telescope, an international network of cooperating astronomical observatories led by the University of Delaware, will be continuously monitoring three of these stars to try to figure out what’s going on inside their luminous masses of cooling plasma.
The primary target is a white dwarf star known as GD358 in the constellation Hercules. It’s made of helium and has a surface temperature estimated at around 19,000 Kelvin.
“We recently discovered that this star is pulsating a little strangely, and we are looking for signs that it is spinning like a top,” says Judi Provencal, assistant professor of physics and astronomy at the University of Delaware and director of the Delaware Asteroseismic Research Center.
A primary mission of the center, which is sponsored by Mt. Cuba Observatory in Greenville, Del., and UD, is to coordinate the activities of the Whole Earth Telescope.
A white dwarf is a “dead” star that doesn’t generate its own energy like the sun does, Provencal says.
“The sun will one day become a white dwarf star, which is why we’re interested in knowing more about them and what happens to any planets the original star might have had,” Provencal notes.
The Whole Earth Telescope’s second target star is the rapidly pulsating PG1325+101 in the constellation Virgo, which is suspected of having one or more planets in orbit around it. The international team will be working to confirm that suspicion, observing the star in collaboration with colleague Roberto Silvotti, leader of the observing group in Italy.
The third target star, WD1524, in the constellation Serpens, was observed during the Whole Earth Telescope’s 2009 international campaign. The star was a high-amplitude pulsator until right before the observing run started, when it mysteriously became a small-amplitude pulsator.
“How stars pulsate depends on their structure and composition,” says Provencal. “Last year, WD1524 completely changed how it was pulsating. Imagine ringing the Liberty Bell and having it sound like a hand bell. That would be hard to do. We don’t understand how this happens with our pulsating stars. We now know that this star has changed yet again, so we are trying to understand how that can happen. Our current theoretical models of white dwarfs don’t predict this sort of behavior.”
There are thousands of white dwarfs in our galaxy; however, only about 30 percent are bright enough for scientists to study using the science of stellar seismology or asteroseismics, which can determine the age, temperature, and composition of a star from its oscillations and brightness.
A white dwarf star pulsates or quakes as waves of energy travel through it. The star’s outer surface sloshes from side to side, like waves on the ocean, Provencal says.
From the shape of these pulses, scientists can measure how the atmosphere is moving around in these pulsating stars and figure out what’s going on inside them, and determine whether an external object like a planet is influencing the star.
The scientific goal of the Whole Earth Telescope is to obtain uninterrupted time-series measurements of “variable stars” — stars whose brightness changes over time — and then construct theoretical models from which their fundamental astrophysics can be derived. The approach, which has been extremely successful, according to Provencal, has placed the fledgling science of “star quakes” at the forefront of stellar astrophysics.
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May 21, 2010
Researchers at Spain’s Centre for Genomic Regulation (CRG) demonstrate evidence in support of the common ancestry of life, thanks to a new computational approach to study protein evolution.
The work, published in Nature, takes its inspiration from the astronomer Edwin Hubble and uses his approach to study protein evolution. The extrapolation of Hubble’s approach to proteins shows that proteins that share a common ancestor billions of years ago continue to diverge in their molecular composition.
The study reveals that protein evolution has not reached its limit and it is still continuing. At the same time, it provides us new information on why this evolution is so slow and conservative, showing that protein structures are more evolutionary plastic than previously thought.
Almost 100 years ago Edwin Hubble observed that distant galaxies are moving away from Earth faster than those that are closer. This relationship between distance and velocity is widely cited as evidence of the origin of the Universe from a Big Bang. Researchers at the Centre for Genomic Regulation used his approach to investigate the divergence between protein sequences.
“We wanted to know if the divergent evolution between proteins was still proceeding. Today, we can find proteins that are still similar after almost 3,5 billion years of evolution. Our study showed that their divergence continues with these proteins becoming more and more different despite their incredible level of conservation,” said Fyodor Kondrashov, principal investigator of the project and leader of the Evolutionary Genomics group at the CRG.
The work done by Kondrashov and Inna Povolotskaya goes beyond similarity studies and discusses the evolution of proteins from the view of evolutionary dynamics, offering a new perspective on how protein structures are maintained in evolution. “In the same way that Hubble’s observations led to an understanding of the past and the future of our universe, using his approach at a molecular level we get a similar overview that gives us the ability to analyze evolutionary dynamics and get a broad prediction of the possible changes to the proteins in the future,” says Povolotskaya, first author of the work and responsible for obtaining and analyzing all data.
Proteins are formed through combinations of amino acids, with only 20 types of amino acids are available to form a particular protein. To obtain the data for their study, the CRG researchers have compared proteins sequences from different species that were available in GenBank, a public database of genetic information. Comparing these sequences the authors measured the distance of proteins from each other and devised a method for measuring how fast the proteins are accumulating different changes. Thus, they could replicate Hubble’s approach by correlating the distance between the proteins with the rate of their divergence. The result indicates that even the most distantly-related proteins are still accumulating differences.
The study shows how new techniques of bioinformatics and computational analysis can also expand knowledge at a molecular level. “Our work is a good example of how we can learn new and very fundamental things just by analyzing a larger volume of data that can be obtained by one experimental laboratory,” says Kondrashov.
Most changes in a protein are deleterious because they somehow disrupt its structure or function. The authors observation that even very conservative proteins are still diverging challenges this view, because it implies that most amino acids in a protein can be changes without any ill effects. Their explanation is that amino acid changes that are deleterious in one combination can be benign when occurring in a different one. “Thanks to our study we now have a better understanding of protein structure dynamics,” says Kondrashov. It may provide a new perspective to groups working on protein structure to find new targets for design drugs, etc.
The Povolotskaya and Kondrashov study also provides new information on how different interactions between different amino acids in the structure of proteins slows down but does not completely prevent evolution.
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Physicists at the Johannes Gutenberg University Mainz have developed a quantum interface which connects light particles and atoms. The interface is based on an ultra-thin glass fiber and is suitable for the transmission of quantum information. This is an essential prerequisite for quantum communication which shall be used for secure data [...]
October 7, 2009
Electron microscopes are the most powerful type of microscope, capable of distinguishing even individual atoms. However, these microscopes cannot be used to image living cells because the electrons destroy the samples.
Now, MIT assistant professor Mehmet Fatih Yanik and his student, William Putnam, propose a new scheme that can overcome this limitation by using [...]
October 7, 2009
It’s often the little things that count in industrial manufacturing processes. Particles less than half the diameter of a hair in size can significantly impair quality in production. For example, there should be no particles larger than five micrometers on the packaging film of food and medicines, as these could contaminate the contents.
Tiny [...]
October 7, 2009
NASA’s Spitzer Space Telescope has discovered an enormous ring around Saturn — by far the largest of the giant planet’s many rings.
The new belt lies at the far reaches of the Saturnian system, with an orbit tilted 27 degrees from the main ring plane. The bulk of its material starts about six million [...]
October 7, 2009
IMEC, one of the leading European research centers in photovoltaics, and BP Solar, a leading energy company, demonstrated a 18% conversion efficiency for silicon solar cells made of BP Solar’s newly developed Mono2TM silicon. By combining IMEC’s advanced processing techniques with BP Solar’s high-quality low-cost substrates, the companies demonstrated that Mono2 has a [...]
October 7, 2009
Researchers have created a CMOS (semiconductor) camera capable of filming individual photons one million times a second.
The scientists wanted to create the fastest, highest resolution CMOS (semiconductor) video camera, but to do that they needed to choose an ultra-fast photo detector. They also needed to choose between two competing timing mechanisms or stopwatches, [...]
October 6, 2009
Crashing a rocket into the Moon will create “one more dimple” on the lunar surface and could find water ice on Earth’s nearest neighbour, according to a Durham University expert.
Dr Vincent Eke’s research has helped inform NASA’s decision about where to crash its probes into the Moon’s surface in search of water.
The Lunar [...]
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