Science & Technology
Sometimes objects in the sky that appear strange, or different from normal, have a story to tell and prove scientifically very rewarding. This was the idea behind Halton Arp's catalogue of Peculiar Galaxies that appeared in the 1960s. One of the oddballs listed there is Arp 261, which has now been imaged in more detail than ever before using the FORS2 instrument on ESO's Very Large Telescope. The image proves to contain several surprises. Arp 261 lies about 70 million light-years distant in the constellation of Libra, the Scales. Its chaotic and very unusual structure is created by the interaction of two galaxies that are engaged in a slow motion, but highly disruptive close encounter. Although individual stars are very unlikely to collide in such an event, the huge clouds of gas and dust certainly do crash into each other at high speed, leading to the formation of bright new clusters of very hot stars that are clearly seen in the picture. The paths of the existing stars in the galaxies are also dramatically disrupted, creating the faint swirls extending to the upper left and lower right of the image. Both interacting galaxies were probably dwarfs not unlike the Magellanic Clouds orbiting our own galaxy.
The images used to create this picture were not actually taken to study the interacting galaxies at all, but to investigate the properties of the inconspicuous object just to the right of the brightest part of Arp 261 and close to the centre of the image. This is an unusual exploding star, called SN 1995N, that is thought to be the result of the final collapse of a massive star at the end of its life, a so-called core collapse supernova. SN 1995N is unusual because it has faded very slowly - and still shows clearly on this image more than seven years after the explosion took place! It is also one of the few supernovae to have been observed to emit X-rays. It is thought that these unusual characteristics are a result of the exploding star being in a dense region of space so that the material blasted out from the supernova plows into it and creates X-rays.
Mon, 16 Mar 2009 16:37 UTC
Space station astronauts had a close call last week with a small piece of orbiting junk, and NASA said Monday that debris from a satellite that broke apart in 1981 could come within about half a mile of the station early Tuesday.
NASA will decide later Monday whether to fire the space station's engines to nudge the complex out of the path of the debris.
Comment: Last month we were told that two satellites collided over Siberia. A few days later, fireballs were caught on video over Texas. Now in a week time we have heard twice of astronauts having to dodge 'space junk'.
Is there something we are not being told about what is going on in our atmosphere?
Mon, 16 Mar 2009 16:13 UTC
The 3,500-year-old filigree flacon bears the name of Hatshepsut, an 18th-dynasty pharaoh who ruled from around 1479 BC.
Michael Hoveler-Muller, the museum's curator, said: "The desiccated residues of a fluid can be clearly discerned in the x-ray photographs... Our pharmacologists are now going to analyze this sediment".
Centuries of work and scholarship had been plowed into alchemical pursuits, and for what? Countless ruined cauldrons, a long trail of empty mystical symbols, and precisely zero ounces of transmuted gold. As a legacy, alchemy ranks above even fantasy baseball as a great human icon of misspent mental energy.
But was it really such a waste? A new generation of scholars is taking a closer look at a discipline that captivated some of the greatest minds of the Renaissance. And in a field that modern thinkers had dismissed as a folly driven by superstition and greed, they now see something quite different.
Alchemists, they are finding, can take credit for a long roster of genuine chemical achievements, as well as the techniques that would prove essential to the birth of modern lab science. In alchemists' intricate notes and diagrams, they see the early attempt to codify and hand down experimental knowledge. In the practices of alchemical workshops, they find a masterly refinement of distillation, sublimation, and other techniques still important in modern laboratories.
Researchers currently produce positrons using one of two methods. At low energies, from a few to a few thousand electron-volts, they are obtained from radioactive isotopes, as in positron emission tomography (PET), a medical imaging technique. Alternatively, particle accelerators can produce positrons with energies of billions of electron-volts.
Hui Chen and Scott Wilks of the Lawrence Livermore National Laboratory in California and their colleagues now report that they have generated copious amounts of positrons with intermediate energies--in the range of a million electron-volts. They fired picosecond pulses with intensities of around 1020 watts per square centimeter from the Titan laser at Livermore's Jupiter laser facility onto millimeter-thick gold targets. Positrons were produced via the "Bethe-Heitler" process, in which part of each laser pulse creates a plasma on the surface of the target, and the remaining part of the pulse then blasts electrons from the plasma into the solid. Next, the electrons are slowed down by gold nuclei, an interaction that generates gamma-ray photons. The gamma rays then interact with more gold nuclei and transform into electron-positron pairs.
With some estimates of armed robots, with so-called Autonomous Navigation Systems, less than five years away, the U.S. Army is drafting a "White Paper," to establish a set of guidelines and principles for their use. "This is a concept paper to think about warfighting outcomes and what robotics will do for soldiers," says U.S. Army Lt. Gen. Michael Vane, who directs the Army Capabilities Integration Center, Fort Monroe, Va. "I am starting out with the idea of having an technology-enabled human. [But] we might someday come up with [separate] IT doctrine and robot doctrine." He reiterates that "we want to make the people or humans in charge under command and control in a 'whole of government' approach." The White Paper will be finished in the coming weeks, Army officials said. (See the most memorable movie robots.)
Gerbrand Ceder and Byoungwoo Kang of the Massachusetts Institute of Technology hope to change this, and thus help make the electric car a work-a-day consumer item, rather than a high-end boy's toy. In this week's Nature they have published the technical details of a new battery material that will, if all goes well, take the waiting out of wanting, at least when it comes to recharging.
Broadly speaking, there are two ways of storing electrical energy in a chemical system. One is a standard battery, in which the whole material of the electrodes acts as a storage medium. That allows lots of energy to be squirrelled away, but makes it relatively hard to get at - and so it can be released or put back in only slowly. The other way is called a supercapacitor. This stores energy only at the surface of the electrode. It is quick to charge and discharge, but cannot hold much energy. The great prize in the battery world has thus been a material that can both store a lot and discharge rapidly, and it is this that Dr Ceder and Mr Kang think they have come up with.
Sun, 15 Mar 2009 00:57 UTC
DeWitt brings his Advanced Creation Studies class up from Liberty University in Lynchburg, Va., hoping to strengthen his students' belief in a biblical view of natural history, even in the lion's den of evolution.
His yearly visit is part of a wider movement by creationists to confront Darwinism in some of its most redoubtable secular strongholds. As scientists celebrate the 200th anniversary of Charles Darwin's birth, his doubters are taking themselves on Genesis-based tours of natural history museums, aquariums, geologic sites and even dinosaur parks.
It appears that the workers, or should we say workmen and artisans, the people who built the rock-cut tombs of the Pharaohs in the Valley of the Kings from about 1500 BC onwards, may have later been employed on a project aimed at "emptying" and "recycling" their contents -- or that, at least, is what Rob Demaree of Leiden University thinks.