Back to the main page

Archives Of Science Blog

Subscribe To Science Blog RSS Feed  RSS content feed What is RSS feed?


January 17, 2006, 0:18 AM CT

Possible Comet Dust Around Dead Star

Possible Comet Dust Around Dead Star An artist's concept of a comet being torn to shreds around a dead star
NASA's Spitzer Space Telescope has spotted what may be comet dust sprinkled around the white dwarf star G29-38, which died approximately 500 million years ago.

The findings suggest the dead star, which most likely consumed its inner planets, is still orbited by a ring of surviving comets and possibly outer planets. This is the first observational evidence that comets can outlive their suns.

"Astronomers have known for decades that stars are born, have an extended middle age, and then wither away or explode. Spitzer is helping us understand how planetary systems evolve in tandem with their parent stars," said David Leisawitz, NASA's Spitzer program scientist.

Astronomers believe white dwarfs are shrunken skeletons of stars that were once similar to Earth's sun. As the stars aged over billions of years, they grew brighter and eventually swelled in size to become red giants. Millions of years later, the red giants shed their outer atmospheres, leaving behind white dwarfs.

If any planets did orbit in these systems, the red giants would have engulfed at least the inner ones. Only distant outer planets and an orbiting icy outpost of comets would have survived.

"The dust seen by Spitzer around G29-38 was probably generated relatively recently when one such outlying comet may have been knocked into the inner region of the system and ripped into dust shreds by the tidal forces of the star," said astronomer William Reach of the Spitzer Science Center at the California Institute of Technology in Pasadena, Calif.........

Posted by: Brooke      Permalink


January 13, 2006, 6:46 PM CT

Mysterious Clouds in Antarctica

Mysterious Clouds in Antarctica The Rothera research station in Antarctica
A new study, funded in part by the Naval Research Laboratory and the National Aeronautics and Space Administration (NASA) reports that exhaust from the space shuttle can create high-altitude clouds over Antarctica mere days following launch, providing valuable insight to global transport processes in the lower thermosphere[mhs1]. The same study also finds that the shuttle's main engine exhaust plume carries small quantities of iron that can be observed from the ground, half a world away.

The international team of authors of the study, to appear in the July 6 issue of Geophysical Research Letters, used the STS-107 Shuttle mission as a case study to show that exhaust released in the lower thermosphere, near 110 kilometers altitude, can form Antarctic polar mesospheric clouds (PMCs). The thermosphere is the highest layer in our atmosphere, with the mesosphere (between 50-90 kilometers above the Earth), stratosphere, and troposphere below.

New observations presented by the research team from the Global Ultraviolet Imager (GUVI) on NASA's Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) satellite reveal transport of the STS-107 exhaust into the southern hemisphere just two days after the January 2003 launch. Water from the exhaust ultimately led to a significant burst of PMCs during the 2002-2003 southern polar summer, observed by the Solar Backscatter Ultraviolet (SBUV) satellite experiment. The inter-hemispheric transport followed by Antarctic PMC formation were unexpected.........

Posted by: Brooke      Permalink


January 13, 2006, 6:42 PM CT

Search for Magic Dust

Search for Magic Dust The Swedish rocket, upon which MAGIC flew
You have probably seen shooting stars, or meteors, in the night sky, but have you ever wondered what happens to the meteoric material after it burns? Researchers in the Naval Research Laboratory's Space Science Division (SSD) are attempting to find out by directly sampling the smoke products thought to be produced by meteors as they burn. The project is called MAGIC: Mesospheric Aerosol: Genesis, Interaction and Composition.

Current theory suggests that up to 44 tons of small, grain-sized meteors burn or "ablate" in the upper atmosphere each day. It is thought that the products of this ablation process are even smaller, nanometer-sized, smoke particles (1/1000th the size of beach sand grains), which form a layer in the atmospheric region known as the mesosphere (50-90 km altitude). In turn these smoke particles are believed to be responsible for the nucleation of the mysterious and beautiful summertime phenomenon known as noctilucent clouds. These smoke particles may also be transported to lower altitudes in the atmosphere, such as the stratosphere (15-50 km altitude) where they may play a role in seeding polar stratospheric clouds, believed to be implicated in polar ozone depletion. Given the potential significance of these particles, it is surprising that they have never actually been detected. Indeed, the acronym for the NRL experiment, MAGIC, is a play on the comment of one scientist who termed these particles "magic dust".........

Posted by: Brooke      Permalink


January 10, 2006, 11:43 PM CT

Spitzer Captures Our Galaxy's Bustling Center

Spitzer Captures Our Galaxy's Bustling Center
A new infrared mosaic from NASA's Spitzer Space Telescope offers a stunning view of the stellar hustle and bustle that takes place at our Milky Way galaxy's center. The picture shows throngs of mostly old stars, on the order of hundreds of thousands, amid fantastically detailed clouds of glowing dust lit up by younger, massive stars.

"With Spitzer, we can peer right into the heart of our own galaxy and see breathtaking detail," said Dr. Susan Stolovy of the Spitzer Science Center at the California Institute of Technology in Pasadena. "This picture is crammed with fascinating features that we have just begun to explore."

The image is available online at http://www.spitzer.caltech.edu/spitzer.

The Milky Way's core is indeed a very busy place. Stars are packed together like subway riders as they race around the supermassive black hole that lies at the center. Our sun is located 26,000 light-years away in a more peaceful, spacious neighborhood, out in the galactic suburbs. It circles the galaxy about every 225 million years, which amounts to 20 trips over the course of its 4.5-billion-year lifetime. In contrast, stars at the galactic center complete one lap in only a few million years or less.

"One question we hope to address is how stars can form so efficiently in a place like the galactic center," said Stolovy. "Stars there are still able to form in an environment with uncommonly strong magnetic fields and tidal shear forces."........

Posted by: Brooke      Permalink


January 10, 2006, 11:38 PM CT

New Nanotechnological Structures Reported

A team of Columbia University and IBM researchers has created conditions necessary for the successful self-assembly of new nanotechnological structures -- at least 10 novel crystal arrangements that could form the basis of tomorrow's leading edge technology, the journal Nature reported in its Jan. 5, 2006 edition.

This scientific breakthrough provides a simpler, less costly method of generating new structures, helping researchers "grow" ordered superlattice crystals, as opposed to manipulating or "machining" them.

Nanotechnology, a scientific field in which the placement of specific atoms or molecules on the scale on nanometers (one billionth of a meter), allows for the assembly of unique structures that have a wide range of manufacturing and technological implications -- from magnetic storage in computer hard drives to surgical robotics to many defense-related technologies.

The findings of Stephen O'Brien, professor of applied physics and applied mathematics and a key member of the Materials Research Science and Engineering Center (MRSEC) at Columbia, along with Columbia postdoctoral research scientist Elena Shevchenko, were published in the Jan. 5, 2006, issue of Nature. MRSEC is an interdisciplinary team of university, industry and national laboratory researchers working together to develop new types of nanocrystals and ways of assembling them into thin films. The work on new structures was conducted in conjunction with Dmitri Talapin and Christopher Murray at the IBM Watson Research Center in Yorktown Heights, New York, and was supported by the National Science Foundation and the New York State Office of Science, Technology and Academic Research.........

Posted by: Jaison      Permalink


January 7, 2006, 6:27 PM CT

Microbes in Marine Sediments

Microbes in Marine Sediments
Marine researchers from the University of Georgia have demonstrated for the first time that temperature affects the biological activity of microbes that degrade organic carbon in marine sediments. Warming global temperatures could therefore cause shifts in the balance of organic carbon that is recycled into the atmosphere or buried in sediments that serve as reservoirs for the substance.

Relatively little has been known until now about how temperature affects this microbial process, which is responsible for the initial breakdown of complex organic matter in sediments, said oceanographer Samantha Joye of the University of Georgia and lead scientist on the study. "What we report was completely unexpected. Temperature short-circuits organic matter recycling," she said.

Joye and coworker, Nathaniel Weston, are publishing their results the week of Nov.14 in the Proceedings of the National Academy of Sciences.

"These surprising results show that temperature strongly affects organic matter breakdown and needs to be taken into account in understanding the role of sediments in the global carbon cycle," said Paul Kemp, program director in the National Science Foundation (NSF)'s Biological Oceanography Program, which supported the research along with NSF's Long-Term Ecological Research (LTER) Program.........

Posted by: Jaison      Permalink


January 4, 2006, 11:08 PM CT

As Amazon's Tree Line Recedes

As Amazon's Tree Line Recedes Mouth Of The Amazon
Researchers have long known that chronic deforestation can spawn a jungle of environmental woes. But now, a study confirms that vanishing forests inflict more than environmental damage: they may cause human diseases, too.

Working in the Peruvian Amazon, a team of scientists from UW-Madison and Johns Hopkins University found that malaria-inducing mosquitoes are likely to bite humans more than 200 times more often in cleared areas versus forested ones. Their results appear this week in the American Journal of Tropical Medicine and Hygiene (Jan. 6, 2005).

"By dramatically changing the landscape, we are tipping the balance in a way that is increasing the risk of malaria transmission," says senior author Jonathan Patz, a former Johns Hopkins scientist and now a professor both in UW-Madison's Nelson Institute for Environmental Studies and the department of population health. "This is one of the most detailed quantitative field studies in the Amazon that directly addresses the potential link between deforestation and malaria."

Over one year, the research team collected mosquitoes at 56 sites in varying stages of deforestation. The sites were located around 14 villages situated along a new road that cuts through the Amazonian rainforest, and connects the towns of Iquitos and Nauta in northeastern Peru. Working in the evenings when mosquitoes are at their thirstiest, the researchers counted how often the insects landed on humans at every site, each of which had been assigned to one of four vegetation categories, including rainforest, shrubby regrowth, cultivated areas and populated villages.........

Posted by: Jaison      Permalink


January 2, 2006, 11:04 PM CT

Revising Earth's Early History

Revising Earth's Early History
Earth's future was determined at birth. Using refined techniques to study rocks, scientists at the Carnegie Institution's Department of Terrestrial Magnetism (DTM) found that Earth's mantle--the layer between the core and the crust--separated into chemically distinct layers faster and earlier than previously believed. The layering happened within 30 million years of the solar system's formation, instead of occurring gradually over more than 4 billion years, as the standard model suggests. The new work was recognized by Science magazine, in its December 23 issue, as one of the science breakthroughs for 2005.

Carnegie researchers Maud Boyet and Richard Carlson analyzed isotopes--atoms of an element with the same number of protons, but a different number of neutrons--of elements in rock samples for their work. As Carlson explains, "Isotopes exist naturally in different proportions and are used to determine conditions under which rock forms. Radioactive isotopes are especially handy because they decay at a predictable rate and can reveal a sample's age and when its chemical composition was established."

In the standard model of the geochemical evolution of the Earth, the Earth's mantle has been evolving gradually over Earth's 4.567-billion-year history primarily through the formation of the chemically distinct continental crust. Shortly after solid material began condensing from the hot gas of the cooling early solar system, the object that would become Earth grew by the collision and accretion of smaller rocky bodies. The chemical composition of these building blocks is preserved today in primitive meteorites called chondrites.........

Posted by: Jaison      Permalink


December 31, 2005, 8:52 PM CT

Evaluating Protons Signatures

Evaluating Protons Signatures Mark A. Johnson
Free protons from acids associate with 1, 2 or 3 molecules of water and the structures can be identified by unique infrared laser spectrum signatures, according to a report in Science by Yale professor of chemistry Mark A. Johnson and his collaborators at Yale, the University of Pittsburgh and the University of Georgia.

Acids yielding free protons are common in biological and chemical systems and the measurement of pH to determine acidity of an aqueous solution is a simple, standard procedure. However, it has not been as easy to determine where the liberated protons are located and how they interact with water molecules.

The researchers tackled these questions using infra-red laser light, at much lower energies than were previously accessible, to monitor how the vibration profile changes when a proton is associated with two to eleven water molecules.

The scientists first established a spectral signature for the symmetrically hydrated Eigen cation, which has a minimum energy (H3O)+ ion core and three associated "dangling" water molecules. As they successively added or subtracted water molecules and compared the spectral signatures, they mimicked water fluctuations.

"Surprisingly large spectral shifts are driven by small changes in the hydration environment," said Johnson. "Eventhough prior work anticipated a change from Zundel to Eigen structures as you progress from 8 to 9 water molecules, the change in the low energy bands here is dramatic. The profile for the 9-membered cluster is much like bulk water, but then the 10-membered cluster is again simpler".........

Posted by: Jaison      Permalink


December 31, 2005, 8:41 PM CT

"Perfume" to Lure Mosquitoes

A five-year, $8.5-million dollar research project, designed to substantially reduce the spread of malaria by redirecting mosquitoes with odor cues, is being undertaken by an international team of researchers including John Carlson, the Eugene Higgins Professor of Molecular, Cellular, and Developmental Biology at Yale University.

The project is one of the 43 "groundbreaking" research projects to improve health in developing countries that have been offered a total of $436 million in support from a Grant from the Foundation for the National Institutes of Health through the Grand Challenges in Global Health initiative. Carlson, will work on a project with researchers at Vanderbilt University, which will administer the award, Wageningen University in the Netherlands, Ifakara Health Research and Development Centre in Tanzania and the Medical Research Council Laboratories in Gambia (Africa).

Hundreds of millions of people are infected with malaria-and hundreds of thousands die-annually. Female malaria mosquitoes "smell" with specialized receptors in their antennae and are drawn to particular human odors that say "dinner." After biting, while the mosquito feeds on blood that is needed for its egg production, parasites from the mosquito enter and infect the human. When an infected person is bitten again, the parasite can be transmitted to an uninfected mosquito and spread further.........

Posted by: Jaison      Permalink


Older Blog Entries   1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23