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August 20, 2006, 9:44 PM CT

Hubble Sees Faintest Stars

Hubble Sees Faintest Stars ancient globular star cluster NGC 6397
The NASA/ESA Hubble Space Telescope has uncovered what astronomers are reporting as the dimmest stars ever seen in any globular star cluster.

Globular clusters are spherical concentrations of hundreds of thousands of stars. Seeing the whole range of stars in this area will yield insights into the age, origin, and evolution of the cluster.

These clusters formed early in the 13.7-thousand-million-year-old universe. The cluster observed by Hubble, called NGC 6397, is one of the closest globular star clusters to Earth.

Eventhough astronomers have conducted similar observations since Hubble was launched, a team led by Harvey Richer of the University of British Columbia, Vancouver, is reporting that they have at last unequivocally reached the faintest stars. Richer's team announced their findings on 17 August at the 2006 International Astronomical Union General Assembly in Prague, Czech Republic, and in the 18 August edition of the journal Science.

"We have run out of hydrogen-burning stars in this cluster. There are no fainter such stars waiting to be discovered," said Richer. "We have discovered the lowest-mass stars capable of supporting stable nuclear reactions in this cluster. Any less massive ones faded early in the cluster's history and by now are too faint to be observed."........

Posted by: Edwin      Permalink         Source


August 20, 2006, 3:07 PM CT

MIT ranks 1st in engineering

MIT ranks 1st in engineering
MIT ranks fourth among national universities, first in undergraduate engineering and second in undergraduate business programs, as per the 2007 US News & World Report guidebook, "America's Best Colleges." The rankings appear today online and the guidebook will be available on newsstands Aug. 21.

MIT shares the number four slot with Caltech and Stanford. Princeton, Harvard and Yale, respectively, are ranked the top three schools.

Among the key criteria for judging schools is selectivity as gauged by the lowest acceptance rate (MIT's is 14 percent), and class size as gauged by the highest proportion of classes with fewer than 20 students (MIT's is 68 percent).

MIT's School of Engineering is the top-rated undergraduate program in engineering nationally, and the Sloan School of Management ranks second in undergraduate business programs. In engineering specialties, MIT was ranked first in more disciplines than any other school -- five out of 12.

In undergraduate engineering specialties, MIT ranked first in aerospace/aeronautical/astronomical; chemical; computer engineering; electrical/electronic/communications; and mechanical engineering. In environmental/environmental health engineering, MIT ranked second, and the Institute ranked fourth in civil engineering, tied with Stanford and University of Texas at Austin. MIT tied for fourth with Georgia Institute of Technology in biomedical engineering and tied for second with the University of California at Berkeley in materials engineering.........

Posted by: John      Permalink         Source


August 20, 2006, 2:59 PM CT

Astronomers proclaim Pluto is a planet

Astronomers proclaim Pluto is a planet
Yes, Virginia, Pluto is a planet.

And it's about to be joined by several more, thanks to a new definition of the word "planet" announced recently by the world's astronomers through the International Astronomical Union (IAU).

The seven-person international panel that spent two years defining the difference between planets and smaller "solar system bodies" such as comets and asteroids includes an MIT astronomer.

If the definition is approved this week at the IAU General Assembly in Prague, our solar system will include 12 planets, with more to come. They include the eight classical planets that dominate the system, three planets in a new and growing category of "plutons" - Pluto-like objects - and Ceres. Pluto remains a planet and is the prototype for the new category of plutons.

"It's time to rewrite the textbooks," said Richard Binzel, an MIT professor of planetary science in the Department of Earth, Atmospheric and Planetary Sciences.

As per the new draft definition, two conditions must be satisfied for an object to be called a planet. First, the object must be in orbit around a star, while not being itself a star. Second, the object must be large enough (or, to be more technically correct, massive enough) for its own gravity to pull it into a nearly spherical shape.........

Posted by: Edwin      Permalink         Source


August 19, 2006, 9:12 PM CT

Stellar Pinwheels At Our Galaxy's Core

Stellar Pinwheels At Our Galaxy's Core
Astronomers have finally learned the identity of a mysterious "Quintuplet Cluster" of stars situated near the supermassive black hole at our galaxy's core: At least two of the objects are not individual stars, but binary pairs that live fast and die young, forming fiery pinwheels as they spin around one another.

A multinational team led by Peter Tuthill of the University of Sydney in Australia, used the extraordinary resolution of the 10-meter telescope at the W.M. Keck Observatory in Hawaii, to determine the nature of the enigmatic objects. They report their findings in the Aug. 18 issue of the journal Science.

Until these observations, scientists had not known whether the extremely red "cocoon" quintuplets were aging stars surrounded by shells of dust, or young stars accompanied by disks of bright gas. Neither hypothesis was convincing, and neither fully explained the enormous light output: Each quintuplet emits 10,000 to 100,000 times as much radiation as the Sun.

The new findings indicate the quintuplets are members of a rare class called "Wolf-Rayet colliding-wind binaries" -- massive, fast-burning star pairs that live only a few million years before exploding in terminal supernovae. By contrast, the Sun is about 5 billion years old and only middle-aged. The pinwheel effect is caused by the way each star's dusty mantle is affected by that of its partner, producing spiral plumes.........

Posted by: Edwin      Permalink         Source


August 17, 2006, 11:31 PM CT

Chip Bounces Electrons Around Like Billiards

Chip Bounces Electrons Around Like Billiards
Computer designers at the University of Rochester are going ballistic.

"Everyone has been trying to make better transistors by modifying current designs, but what we really need is the next paradigm," says Quentin Diduck, a graduate student at the University who thought up the radical new design. "We've gone from the relay, to the tube, to semiconductor physics. Now we're taking the next step on the evolutionary track".

That next step goes by the imposing name of "Ballistic Deflection Transistor," and it's as far from traditional transistors as tubes. Instead of running electrons through a transistor as if they were a current of water, the ballistic design bounces individual electrons off deflectors as if playing a game of atomic billiards.

Though today's transistor design has many years of viability left, the amount of heat these transistors generate and the electrical "leaks" in their ultra-thin barriers have already begun to limit their speed. Research groups around the world are investigating strange new designs to generate ways of computing at speeds unthinkable with today's chips. Some of these groups are working on similar single-electron transistors, but these designs still compute by starting and stopping the flow of electrons just like conventional designs. But the Ballistic Deflection Transistor adds a new twist by bouncing the electrons into their chosen trajectories-using inertia to redirect for "free," instead of wrestling the electrons into place with brute energy.........

Posted by: John      Permalink         Source


August 14, 2006, 10:00 PM CT

Large and small stars in harmonious coexistence

Large and small stars in harmonious coexistence
The latest photo from the Hubble Space Telescope, presented at the 2006 General Assembly of the International Astronomical Union in Prague this week, shows a star forming region in the Large Magellanic Cloud (LMC).

This image reveals a large number of low-mass infant stars coexisting with young massive stars.........

Posted by: Edwin      Permalink         Source


August 13, 2006, 6:58 PM CT

Nanotubes Not for Toothpaste

Nanotubes Not for Toothpaste
When researchers fire electron beams at multi-layered carbon nanotubes, they collapse, much like a tube of toothpaste, with such force the nanotubes extrude whatever may be inside, even extremely hard iron carbide. The process--which has applications for manufacturing durable, metal nanowires and similar materials--creates pressures within the tubes that reach one-tenth the crushing force in the Earth's core.

National Science Foundation-supported researcher Pulickel Ajayan of Rensselaer Polytechnic Institute (RPI) worked with an international team to develop the process. First, the researchers constructed long nanotubes of onion-like layers of carbon containing a 9-nanometer (billionth of a meter) core of iron or iron carbide, and then they blasted the tube with a beam of electrons. The tube collapsed, extruding an iron-carbide wire only 2 nanometers in diameter. What's more, the tube neatly pinched off the wire's end where the tube collapsed completely.

The findings appeared in the May 26, 2006, issue of the journal Science. Florian Banhart of Johannes Gutenberg University in Mainz, Germany, led the team, which included colleagues at the Institute for Scientific and Technological Research in San Luis Potosi, Mexico, and the University of Helsinki in Finland.........

Posted by: John      Permalink         Source


August 13, 2006, 6:53 PM CT

A Digital Take On The Streets Where We Live

A Digital Take On The Streets Where We Live
A walk down the street may someday be as rich with information as the web, thanks to the emergence of location-aware technology.

Not surprisingly, MIT is at the vanguard of this movement with a project called Electronic Lens (eLens), an initiative of the MIT Media Lab. Headed by William Mitchell and Federico Casalegno, eLens is defined by its focus on benefits for local citizens.

Several research and commercial projects are also exploring the potential of location-aware services. Most rely on a tagging system - for example, physical tags attached to buildings - that can then be scanned and read by mobile camera phones.

eLens is exploring the next wave of communications technology - building interactions that depend on where you are and what you want to know or say. In the eLens team's vision, you could aim your mobile phone at your child's school and start a voice thread to discuss cuts in after-school programs. Or you could let passersby know that the local folk music club serves great vegetarian meals.

The project began with a metaphor, that of an electronic lens that can be aimed at civic institutions and a "viewfinder" that makes these institutions more transparent. Pointing eLens at a train station, for example, might let you retrieve the day's schedule for different tracks. Pointing it at a museum might list current exhibits and upcoming lectures.........

Posted by: John      Permalink         Source


August 9, 2006, 11:59 PM CT

An Oblique Look On The North Lunar Far West

An Oblique Look On The North Lunar Far West An 'oblique' view of the lunar surface towards the limb, around the Mezentsev, Niepce and Merrill craters
This image, taken by the Advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 spacecraft, provides an 'oblique' view of the lunar surface towards the limb, around the Mezentsev, Niepce and Merrill craters, on the far side of the Moon.

"This cratered terrain is similar in topography to near-side highlands," says SMART-1 Project scientist Bernard Foing, "while the far-side equator bulge can reach heights of 7 km, and the South Pole Aitken basin has depths down to 8 km".

AMIE obtained this sequence on 16 May 2006. The imaged area is centred at a latitude of 73º North and a longitude of 124º West(or 34 º further than the West limb seen from Earth).

Normally, the SMART-1 spacecraft points the AMIE camera straight down, in the so-called Nadir pointing mode. In this image, AMIE was looking out 'the side window' and pointing towards the horizon, showing all craters in an oblique view. The largest craters shown are Mezentesev, Niepce and Merrill, located on the lunar far side, not visible from the Earth. Mezentsev is an eroded crater 89 kilometres in diameter, while Niepce and Merrill have the same size 57 km.

Mezentsev is named after Yourij Mezentsev, a Soviet engineer (1929 - 1965) who was one of the first people to design rocket launchers. Joseph Niepce was the French inventor of photography (1765 - 1833), while Paul Merrill was an American astronomer (1887 - 1961).........

Posted by: Edwin      Permalink         Source


August 9, 2006, 7:20 AM CT

New Rocket Technology From Purdue

New Rocket Technology From Purdue
Purdue University engineers are conducting research to help NASA develop rockets faster and less expensively for future missions to Mars and the moon.

The NASA-funded research at Purdue focuses on liquid-fueled rockets. Specifically, the work deals with understanding how fuel and a component called the oxidizer interact inside the rocket engine's fuel injectors to cause unstable combustion. The instability results in extreme bursts of heat and pressure fluctuations that could lead to accidents and hardware damage.

Purdue engineers involved in the research earned a best paper award in July from the American Institute of Aeronautics and Astronautics.

"Combustion instability is a complex phenomenon that has hindered rocket development since the beginning of the Space Age," said Nicholas Nugent, a doctoral student in Purdue's School of Aeronautics and Astronautics. "We have to learn more about instability before future engines can be developed and used for space flight. Predicting combustion instability is one of the most difficult aspects of developing a rocket engine."

The paper's findings demonstrate that an experiment can be specifically designed to study instabilities occurring spontaneously, as they do in real engines.

"There haven't been a number of, if any, experiments in the past that have been able to achieve an instability without actually forcing it by introducing artificial influences not ordinarily seen in the operation of a rocket engine," said doctoral student James Sisco.........

Posted by: John      Permalink         Source


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