December 11, 2006, 9:32 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 researchers -- 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. "A number of 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.........

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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 researchers 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.........

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November 22, 2006, 4:32 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.........

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November 7, 2006, 4:56 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 many 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 many 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, 9:17 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 mandatory to displace the gas exceeded the power output of the Sun by nearly ten trillion times in the past 100 million years.........

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October 27, 2006, 5:04 AM CT

Latest views of the V838

Hubble has returned to the intriguing V838 Monocerotis a number of times since its initial outburst in 2002 to follow the evolution of its light echo. Two new images provide the most astonishing views of V838 to date.

The unusual variable star V838 Monocerotis (V838 Mon) continues to puzzle astronomers. This previously inconspicuous star underwent an outburst early in 2002, during which it temporarily increased in brightness to become 600,000 times more luminous than our Sun. Light from this sudden eruption is illuminating the interstellar dust surrounding the star, producing the most spectacular "light echo" in the history of astronomy.

As light from the eruption propagates outward into the dust, it is scattered by the dust and travels to the Earth. The scattered light has travelled an extra distance compared to light that reaches Earth directly from the stellar outburst. Such a light echo is the optical analogue of the sound echo produced when an Alpine yodel is reflected from the surrounding mountainsides.

The NASA/ESA Hubble Space Telescope has been observing the V838 Mon light echo since 2002. Each new observation of the light echo reveals a new and unique "thin-section" through the interstellar dust around the star. This release shows new images of the light echo from the Hubble Advanced Camera for Surveys taken in November 2005 (left) and again in September 2006 (right). The numerous whorls and eddies in the interstellar dust are especially noticeable. Possibly they have been produced by the effects of magnetic fields in the space between the stars.........

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October 26, 2006, 5:04 AM CT

200-million-year-old Baby Galaxies

Astronomers have taken amazing pictures of two of the most distant galaxies ever seen. The ultradeep images, taken at infrared wavelengths, confirm for the first time that these celestial cherubs are real. The researchers* are now able to weigh galaxies and determine their age at earlier times than ever before, providing important clues about the evolutionary origins of galaxies like our Milky Way. The work appears in the October 1 issue of Astrophysical Journal Letters.

Carnegie Fellow Ivo Labbe, along with Rychard Bouwens and Garth Illingworth of the UCO/Lick Observatory at the University of California, Santa Cruz, and Marijn Franx of the Leiden Observatory, examined galaxies in the Hubble Ultra Deep Field (HUDF) using the sensitive Infrared Array Camera (IRAC) aboard NASA's Spitzer Space Telescope. The HUDF, scanned by NASA's Hubble Space Telescope in late 2003, remains the deepest view ever taken at visible and near-infrared wavelengths.

The two galaxies are seen when the universe was just a baby-700 million years after the Big Bang, or five percent of the universe's current age. They belong to a precious small sample of similarly ancient galaxies, discovered two years ago by Bouwens, Illingworth, and Franx and analyzed in-depth in Nature last month. The relative deficit of such far-away luminous sources indicates that this early period is when galaxies were rapidly building up from a very small number of stars to the massive galaxies we see at later times.........

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October 16, 2006, 9:35 PM CT

Day And Night On The Exotic World

NASA's Spitzer Space Telescope has made the first measurements of the day and night temperatures of a planet outside our solar system. The infrared observatory revealed that the Jupiter-like gas giant planet circling very close to its sun is always as hot as fire on one side, and potentially as cold as ice on the other.

"This planet has a giant hot spot in the hemisphere that faces the star," said Dr. Joe Harrington of the University of Central Florida, Orlando, lead author of a paper appearing online today in Science. "The temperature difference between the day and night sides tells about how energy flows in the planet's atmosphere. Essentially, we're studying weather on an exotic planet".

The finding represents the first time any kind of variation has been seen across the surface of an extrasolar planet, a planet beyond our solar system. Prior measurements of extrasolar planets described only global traits like size and mass.

"This is a spectacular result," said Dr. Michael Werner, project scientist for Spitzer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "When we designed Spitzer years ago, we did not anticipate that it would be revolutionizing extrasolar-planet science."

The scientists used Spitzer to determine the temperature variation in the atmosphere of a nearby planet called Upsilon Andromedae b. This "hot-Jupiter" planet is a gas giant similar to Jupiter, but it orbits very close to its scorching star, circling the star once every 4.6 days.........

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October 12, 2006, 8:00 PM CT

Secrets Of Black Hole Jets

NASA and Italian researchers using Swift have for the first time determined what the particle jets streaming from black holes are made of.

Black hole particle jets are usually seen in quasars and other celestial objects, shooting off at nearly light speed. As per the Swift team, these jets appear to be made of protons and electrons, solving a mystery as old as the discovery of jets themselves in the 1970s. The jets observed by Swift contain about the mass of Jupiter if it were pulverized and blasted out into intergalactic space.

Black hole particle jets typically escape the confines of their host galaxies and flow for hundreds of thousands of light years. They are a primary means of redistributing matter and energy in the universe. They are a key to understanding galaxy formation and are tied to numerous cosmic mysteries, such as the origin of ultrahigh-energy cosmic rays.

"Black hole jets are one of the great paradoxes in astronomy," said Rita Sambruna of NASA's Goddard Space Flight Center, Greenbelt, Md. "How is it that black holes, so efficient at pulling matter in, can also accelerate matter away at near light speed? We still don't know how these jets form, but at least we now have a solid idea about what they're made of".

The composition of black hole jets has been the topic of heated debate for several decades. Researchers generally agree that the jets must be made either of electrons and their antimatter partners, called positrons, or an even mix of electrons and protons. Recent theoretical and observational advances have pointed in the direction of the latter. The Swift data provides the most compelling evidence to date that the jets must have protons.........

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October 10, 2006, 9:25 PM CT

Nobelists' Work Supports Big-bang Theory

MIT alumnus George F. Smoot has been awarded the 2006 Nobel Prize in physics, together with John C. Mather, for work that looks back into the infancy of the universe and attempts to gain some understanding of the origin of galaxies and stars.

The work, based on measurements of the cosmic microwave background radiation made with NASA's COBE satellite, provides increased support for the big-bang theory of the origin of the universe. The COBE (Cosmic Background Explorer) measurements also mark the inception of cosmology as a precise science. For the first time, cosmological calculations could be compared with data from real measurements.

According to the big bang scenario, the cosmic microwave background radiation is a relic of the earliest phase of the universe. Immediately after the big bang itself, the universe can be compared to a glowing body emitting radiation at a temperature of almost 3,000 degrees Celsius.

Since then, the radiation has cooled as the universe has expanded. The background radiation we can measure today corresponds to a temperature that is barely 2.7 degrees above absolute zero. The new Nobel laureates were able to calculate this temperature thanks to the COBE measurements.

COBE also had the task of seeking small variations of temperature in the cosmic background radiation in different directions. Extremely small differences of this kind--in the range of a hundred-thousandth of a degree--offer an important clue to how the galaxies came into being. The variations in temperature measured by COBE show us how the matter in the universe began to "aggregate." This was necessary if the galaxies, stars and ultimately life forms like us were to be able to develop.........

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