December 11, 2006, 9:33 PM CT

Predicted Present Day Distribution Of Elusive First Stars

With the help of enormous computer simulations, astronomers have now shown that the first generation of stars -- which have never been observed by scientists -- should be distributed evenly throughout our galaxy, deepening the long-standing mystery about these missing stellar ancestors. The results are published in this week's issue of the Astrophysical Journal.

The problem is that despite years of looking, no one has ever found any of these stars. "Many astronomers thought this was because the stars without heavy elements were hidden from us," said Evan Scannapieco, first author and a postdoctoral fellow at the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara. "Because our galaxy formed from the inside out, the idea was that these very old stars would all be near the center. But the center of Milky Way is extremely crowded with dust and newer stars, making it very hard to detect individual old stars in this environment".

This earliest generation of stars should look very different from later-forming stars like the Sun; yet so far, no one has detected a survivor from this primordial population. One of the long-standing explanations for this discrepancy was that these stars might all be contained in regions near the center of the Milky Way, where they are very hard to observe. The results of the new study make that explanation unlikely.........

Posted by: Brooke      Permalink         Source

December 6, 2006, 8:29 PM CT

Galaxies And Darwinian Evolution

Using VIMOS on ESO's Very Large Telescope, a team of French and Italian astronomers have shown the strong influence the environment exerts on the way galaxies form and evolve. The scientists have for the first time charted remote parts of the Universe, showing that the distribution of galaxies has considerably evolved with time, depending on the galaxies' immediate surroundings. This surprising discovery poses new challenges for theories of the formation and evolution of galaxies.

The 'nature versus nurture' debate is a hot topic in human psychology. But astronomers too face similar conundrums, in particular when trying to solve a problem that goes to the very heart of cosmological theories: are the galaxies we see today simply the product of the primordial conditions in which they formed, or did experiences in the past change the path of their evolution?

In a large, three-year long survey carried out with VIMOS [1], the Visible Imager and Multi-Object Spectrograph on ESO's VLT, astronomers studied more than 6,500 galaxies over a wide range of distances to investigate how their properties vary over different timescales, in different environments and for varying galaxy luminosities [2]. They were able to build an atlas of the Universe in three dimensions, going back more than 9 billion years.........

Posted by: Brooke      Permalink         Source

November 28, 2006, 8:18 PM CT

First ever Gamma Ray Clock

Astronomers using the H.E.S.S. telescopes have discovered the first ever modulated signal from space in Very High Energy Gamma Rays - the most energetic such signal ever observed. Regular signals from space have been known since the 1960s, when the first radio pulsar (nicknamed Little Green Men-1 for its regular nature) was discovered. This is the first time a signal has been seen at such high energies - 100,000 times higher than previously known - and is reported today (24th November) in the Journal Astronomy and Astrophysics.

The signal comes from a system called LS 5039 which was discovered by the H.E.S.S. team in 2005. LS5039 is a binary system formed of a massive blue star (20 times the mass of the Sun) and an unknown object, possibly a black hole. The two objects orbit each other at very short distance, varying between only 1/5 and 2/5 of the separation of the Earth from the Sun, with one orbit completed every four days.

"The way in which the gamma ray signal varies makes LS5039 a unique laboratory for studying particle acceleration near compact objects such as black holes." Explained Dr Paula Chadwick from the University of Durham, a British team member of H.E.S.S.

Different mechanisms can affect the gamma-ray signal that reaches Earth and by seeing how the signal varies, astronomers can learn a great deal about binary systems such as LS 5039 and also the effects that take place near black holes.........

Posted by: Brooke      Permalink         Source

November 22, 2006, 4:39 AM CT

NASA Nanotechnology Comes to Market

Finding affordable ways to make technology available to everyone is a common challenge. Now, NASA has done that with the process that creates "nanotubes."

A nanotube is a tiny, hollow, long, thin and strong tube with an outside diameter of a nanometer that is formed from atoms such as carbon. A hair from a person's head is around 50,000 nanometers wide. If you split a hair into 50,000 strands, that would be the width of a nanometer.

Nanotubes are really important in technology, because when they are made a certain way, a nanotube can conduct (allow movement of) electricity as well as copper does. When they are made a slightly different way, nanotubes are electrical semiconductors, which mean they can be switched between insulating from electricity to conducting electricity. Semiconductors make it possible to miniaturize electronic components. Nanotubes can be either semiconductors or conductors depending on how they are made.

Nanotubes are also stronger than steel, so long filaments can be used to create super-tough lightweight materials. To understand how strong a nanotube is, think of a hair holding up a barbell.

Eventhough the carbon nanotubes were discovered 15 years ago, their use has been limited due to the complex, dangerous, and expensive methods for their production.........

Posted by: Kevin      Permalink         Source

November 22, 2006, 4:33 AM CT

First Live HDTV Broadcast From Space

Images from the world's first high definition television (HDTV) broadcast from space flashed across the screen on Nov 15th in Times Square. On Nov. 15, 2006, NASA made history with the first live HDTV broadcasts from space, in cooperation with the Japan Aerospace Exploration Agency, Discovery HD Theater and Japanese broadcast network NHK.

The two HDTV broadcasts featured Expedition 14 Commander Michael Lopez-Alegria on the International Space Station, with Flight Engineer Thomas Reiter serving as camera operator aboard the 220-mile-high laboratory.

"HDTV provides up to six times the resolution of regular analog video," said Rodney Grubbs, NASA principal investigator. "On prior missions, we've flown HDTV cameras but had to wait until after the mission to retrieve the tapes, watch the video and share it with the science and engineering community, the media and the public. For the first time ever, this test lets us stream live HDTV from space so the public can experience what its like to be there".

Known as the Space Video Gateway, the system transmits high bandwidth digital television signals to the ground that are not only spectacular, but also valuable to scientists, engineers and managers.

NASA and the Japan Aerospace Exploration Agency, along with both NHK and Discovery, are cooperating in this effort though a Space Act Agreement originally signed in 2002.........

Posted by: Brooke      Permalink         Source

November 7, 2006, 4:55 AM CT

Measuring Natural Airglow In The Upper Atmosphere

The second of five Special Sensor Ultraviolet Limb Imager (SSULI) remote sensing instruments, developed by the Naval Research Laboratory, was launched on November 4, 2006 on board the DMSP F-17 satellite. SSULI is the first operational instrument of its kind and provides a new technique for remote sensing of the ionosphere and thermosphere from space. SSULI's measurements will provide scientific data supporting military and civil systems and will assist in predicting atmospheric drag effects on satellites and reentry vehicles.

A Boeing Delta 4 vehicle launched the Air Force's Defense Meteorological Satellite Program (DMSP) F-17 satellite and the SSULI sensor into low earth orbit from Vandenberg Air Force Base, California. SSULI will be powered on and start initial sensor checkout 30 days after launch.

"Characterization of the Earth's upper atmosphere and ionosphere is a critical goal for Department of Defense (DoD) and civilian users," said Andrew Nicholas, the SSULI Principal Investigator at NRL. He discussed the significance of the planned SSULI observations, saying, "The upper atmosphere affects a number of systems from global to tactical scales. These systems include GPS positioning, HF radio communications, satellite drag and orbit determination, and over-the-horizon radar. Both the neutral atmosphere and the ionosphere are driven by solar and geomagnetic forcing that occur on a number of timescales ranging from short (minute, hours) to medium (days to months) to long (years). Real-time global observations that yield altitude profiles of the ionosphere and neutral atmosphere, over an extended period of time (DMSP through the year 2016) will fill a critical need."........

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November 6, 2006, 9:21 PM CT

Mars Science Laboratory Shakedown in the High Arctic

Members of the AMASE team (AMASE stands for Arctic Mars Analog Svalbard Expedition) last month completed their fourth field season on the Arctic island of Spitsbergen. They went to test out instruments similar to those that will fly on an upcoming mission to Mars, and to perform a field test of a prototype rover, Cliff-bot, that is capable of climbing up and down 80-degree slopes.

Spitsbergen is the largest island in the Norwegian Svalbard archipelago, which lies between the northern tip of Norway and the northern polar ice cap. It is an inviting destination for astrobiology scientists because it contains several Mars analog sites: geologic formations that resemble, in various ways, ones on Mars.

One such site contains Devonian-age redbeds, formed between 408 and 360 million years ago. Such red-rock formations are a familiar sight in the American southwest, eventhough there they are typically older. The redbeds in Svalbard, composed of rust-colored fluvial sandstones and mudstones, which contain the iron-bearing mineral hematite, are reminiscent of regions of layered terrain seen on Mars in images taken by orbiting spacecraft.

Svalbard's "blueberry site" was selected because sulfate-bearing sandstones there contain small spherical concretions similar to the "blueberries" found by NASA's Opportunity rover in Meridiani Planum. The martian concretions, which contain hematite, helped researchers confirm the former presence of liquid water on Mars. The Svalbard concretions do not contain hematite; they are rich in sulfate and carbonate minerals that also form in the presence of liquid water. Interestingly these concretions contain evidence of cryptoendolithic communities.........

Posted by: Tyler      Permalink         Source

November 6, 2006, 9:17 PM CT

Monstrous Black Hole Blast in the Core of a Galaxy Cluster

This is a composite image of galaxy cluster MS0735.6+7421, located about 2.6 billion light-years away in the constellation Camelopardus. The image represents three views of the region that astronomers have combined into one photograph. The optical view of the galaxy cluster, taken by the Hubble Space Telescope's Advanced Camera for Surveys in February 2006, shows dozens of galaxies bound together by gravity.

Diffuse, hot gas with a temperature of nearly 50 million degrees permeates the space between the galaxies. The gas emits X-rays, seen as blue in the image taken with the Chandra X-ray Observatory in November 2003. The X-ray portion of the image shows enormous holes or cavities in the gas, each roughly 640,000 light-years in diameter -- nearly seven times the diameter of the Milky Way.

The cavities are filled with charged particles gyrating around magnetic field lines and emitting radio waves shown in the red portion of image taken with the Very Large Array telescope in New Mexico in June 1993. The cavities were created by jets of charged particles ejected at nearly light speed from a supermassive black hole weighing nearly a billion times the mass of our Sun lurking in the nucleus of the bright central galaxy. The jets displaced more than one trillion solar masses worth of gas. The power required to displace the gas exceeded the power output of the Sun by nearly ten trillion times in the past 100 million years.........

Posted by: Brooke      Permalink         Source

October 31, 2006, 6:44 PM CT

Crab Nebula

The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, expanding debris from the death explosion of a massive star. This intriguing false-color image combines data from space-based observatories, Chandra, Hubble, and Spitzer, to explore the debris cloud in x-rays (blue-purple), optical (green), and infrared (red) light.

One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is the bright spot near picture center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is 6,500 light-years away in the constellation Taurus.........

Posted by: Brooke      Permalink         Source

October 27, 2006, 4:33 AM CT

Cracking The Stellar Evolution

Using 3D models run on some of the fastest computers in the world, Laboratory physicists have created a mathematical code that cracks a mystery surrounding stellar evolution.

For years, physicists have theorized that low-mass stars (about one to two times the size of our sun) produce great amounts of helium 3 (³He). When they exhaust the hydrogen in their cores to become red giants, most of their makeup is ejected, substantially enriching the universe in this light isotope of helium.

This enrichment conflicts with the Big Bang predictions. Scientists theorized that stars destroy this ³He by assuming that nearly all stars were rapidly rotating, but even this failed to bring the evolution results into agreement with the Big Bang.

Now, by modeling a red giant with a fully 3D hydrodynamic code, LLNL researchers identified the mechanism of how and where low-mass stars destroy the ³He that they produce during evolution.

They found that ³He burning in a region just outside of the helium core, previously thought to be stable, creates conditions that drive this newly discovered mixing mechanism.

Bubbles of material, slightly enriched in hydrogen and substantially depleted in ³He, float to the surface of the star and are replaced by ³He-rich material for additional burning. In this way the stars destroy their excess ³He, without assuming any additional conditions (like rapid rotation).........

Posted by: Brooke      Permalink         Source