January 11, 2007, 6:26 PM CT

How to Swallow A Thermometer

From the football turf to high above the Earth, heat exhaustion can be life-threatening. Now the same type of "thermometer pill" that astronaut John Glenn swallowed as part of space shuttle medical experiments is also helping athletes to beat the heat.

Just as an engine overheats on a hot day, heat exhaustion -- or hyperthermia -- occurs when the body retains too much heat due to extreme environmental conditions or increased internal heat production. This is particularly dangerous among football players. Athletes may train when the heat index is above 100 degree F, all while wearing heavy pads that not only retain heat, but also increase their body weight.

Heat exhaustion can turn to heatstroke, causing the body's heat-regulating mechanisms to falter and fail. Ultimately this can lead to brain damage, organ damage, and eventually death. Heatstroke is the third leading cause of death among athletes in the United States.

Astronauts working in space face a similar threat. During activities such as spacewalks, astronauts may perform strenuous activity that causes a rapid rise in body temperature. A space suit is insulated against external temperature extremes because the side facing the sun can heat to 250 degree F, and the side facing deep space can plunge to -250 degree F. The danger of overheating comes from within as astronauts release body heat and humidity inside the suits, potentially causing heat illnesses.........

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January 11, 2007, 4:57 AM CT

Light Echo From The Milky Way's Black Hole

Like cold case investigators, astronomers have used NASA's Chandra X-ray Observatory to uncover evidence of a powerful outburst from the giant black hole at the Milky Way's center.

A light echo was produced when X-ray light generated by gas falling into the Milky Way's supermassive black hole, known as Sagittarius A* (pronounced "A-star"), was reflected off gas clouds near the black hole. While the primary X-rays from the outburst would have reached Earth about 50 years ago, the reflected X-rays took a longer path and arrived in time to be recorded by Chandra.

"This dramatic event happened before we had satellites in space that could detect it," said Michael Muno of the California Institute of Technology in Pasadena. "So, it's remarkable that we can use Chandra to dig into the past and see this monster black hole's capacity for destruction".

Previously, scientists have used Chandra to directly detect smaller and more recent outbursts from the black hole. This latest outburst revealed by the X-ray echo was about 1,000 times brighter and lasted well over 1,000 times longer than any of the recent outbursts observed by Chandra.

Theory predicts that an outburst from Sagittarius A* would cause X-ray emission from the clouds to vary in both intensity and shape. Muno and his team found these changes for the first time, thus ruling out other interpretations. The latest results corroborate other independent, but indirect, evidence for light echoes generated by the black hole in the more distant past.........

Posted by: Brooke      Read more         Source

January 9, 2007, 9:56 PM CT

Story Of A Star Death

Using NASA's Chandra X-ray Observatory, scientists have created a stunning new image of one of the youngest supernova remnants in the galaxy. This new view of the debris of an exploded star helps astronomers solve a long-standing mystery, with implications for understanding how a star's life can end catastrophically and for gauging the expansion of the universe.

Over 400 years ago, sky watchers -- including the famous astronomer Johannes Kepler -- noticed a bright new object in the night sky. Since the telescope had not yet been invented, only the unaided eye could be used to watch as a new star that was initially brighter than Jupiter dimmed over the following weeks.

Chandra's latest image marks a new phase in understanding the object now known as Kepler's supernova remnant. By combining nearly nine days of Chandra observations, astronomers have generated an X-ray image with unprecedented detail of one of the brightest recorded supernovas in the Milky Way galaxy.

The explosion of the star that created the Kepler remnant blasted the stellar remains into space, heating the gases to millions of degrees and generating highly energized particles. Copious X-ray light, like that shining from many supernova remnants, was produced.

Astronomers have studied Kepler intensively over the past three decades with radio, optical and X-ray telescopes, but its origin has remained a puzzle. On the one hand, the presence of large amounts of iron and the absence of a detectable neutron star points toward a so-called Type Ia supernova. These events occur when a white dwarf star pulls material from an orbiting companion until the white dwarf becomes unstable and is destroyed by a thermonuclear explosion.........

Posted by: Brooke      Read more         Source

January 9, 2007, 9:32 PM CT

Dust Around Nearby Star Like Powder Snow

Astronomers peering into the dust surrounding a nearby red dwarf star have found that the dust grains have a fluffiness comparable to that of powder snow, the ne plus ultra of skiers and snowboarders.

This is the first definitive measurement of the porosity of dust outside our solar system, and is akin to looking back 4 billion years into the early days of our planetary system, say researchers at the University of California, Berkeley. That was the era after the formation of planets, but before the remaining snowball- or softball-sized rubble was ground into dust by collisions and blown out of the inner solar system.

"We believe that this porosity is primordial, and reflects the agglomeration process whereby interstellar grains first assembled to form macroscopic objects," said James Graham, UC Berkeley professor of astronomy.

The grains are probably microscopic dirty snowballs, a mixture of ice and rock.

"The difference between a snowflake and a hailstone - both are ice but with very different porosities - occurs because they form very differently," he added. "Hailstones grow in violent thunderstorms; snowflakes grow under much more sedate meteorological conditions. Similarly, we conclude that the dust grains in the AU Mic debris disk formed by gentle agglomeration".........

Posted by: Brooke      Read more         Source

January 9, 2007, 8:42 PM CT

Diamonds From Outer Space

If indeed "a diamond is forever," the most primitive origins of Earth's so-called black diamonds were in deep, universal time, geologists have discovered. Black diamonds came from none other than interstellar space.

In a paper published online on December 20, 2006, in the journal Astrophysical Journal Letters, researchers Jozsef Garai and Stephen Haggerty of Florida International University, along with Case Western Reserve University scientists Sandeep Rekhi and Mark Chance, claim an extraterrestrial origin for the unique black diamonds, also called carbonado diamonds.

Infrared synchrotron radiation at Brookhaven National Laboratory was used to discover the diamonds' source.

"Trace elements critical to an 'ET' origin are nitrogen and hydrogen," said Haggerty. The presence of hydrogen in the carbonado diamonds indicates an origin in a hydrogen-rich interstellar space, he and his colleagues believe.

The term carbonado was coined by the Portuguese in Brazil in the mid-18th century; it's derived from its visual similarity to porous charcoal. Black diamonds are found only in Brazil and the Central African Republic.

"Conventional diamonds are mined from explosive volcanic rocks [kimberlites] that transport them from depths in excess of 100 kilometers to the Earth's surface in a very short amount of time," said Sonia Esperanca, program director in the National Science Foundation's Division of Earth Sciences, which funded the research. "This process preserves the unique crystal structure that makes diamonds the hardest natural material known".........

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January 7, 2007, 9:03 PM CT

An Enormous Halo Of Red Giant Stars

Astronomers have found an enormous halo of stars bound to the Andromeda galaxy and extending far beyond the swirling disk seen in images of the famous galaxy, our nearest large galactic neighbor. The discovery, reported at the American Astronomical Society meeting in Seattle, suggests that Andromeda is as much as five times larger than astronomers had previously thought.

"I am absolutely astounded by how big this halo is. As we looked farther and farther out, we kept finding stars that look like halo stars," said Puragra (Raja) Guhathakurta, professor of astronomy and astrophysics at the University of California, Santa Cruz, who will present the findings at the meeting.

Guhathakurta and his collaborators at UCSC, UCLA, and the University of Virginia are conducting an ongoing study of Andromeda's stellar halo, using observations at the Kitt Peak National Observatory in Arizona and the W. M. Keck Observatory in Hawaii. Their new findings are based on data gathered using the 4-meter Mayall Telescope at Kitt Peak and the DEIMOS spectrograph on the 10-meter Keck II Telescope in Hawaii.

The researchers detected a sparse population of red giant stars--bright, bloated stars in a late stage of stellar evolution--that appear to be smoothly distributed around the galaxy out to a distance of at least 500,000 light-years from the center. Even at that great distance, the stars are bound to the galaxy by gravity. These stars probably represent Andromeda's stellar halo, a distinct structural component of the galaxy that has eluded astronomers for over 20 years, Guhathakurta said.........

Posted by: Brooke      Read more         Source

January 7, 2007, 8:48 AM CT

A New Class Of Supernova

Evidence for a significant new class of supernova has been found with the European Space Agency's XMM-Newton and NASA's Chandra X-ray Observatory. These results strengthen the case for a population of stars that evolve rapidly and are destroyed by thermonuclear explosions. Such 'prompt' supernovas could be valuable tools for probing the early history of the cosmos.

A team of astronomers uncovered a puzzling situation when they examined X-ray data from DEM L238 and DEM L249, the remnants of two supernovas in a nearby galaxy. On the one hand, the unusually high concentration of iron atoms implied that the remnants are the products of thermonuclear explosions of white dwarf stars, a well-known type of supernova known as 'Type Ia'. On the other hand, the hot gas in the remnants was much denser and brighter in X-rays than typical Type Ia remnants.

(The large image shows a composite of Chandra X-ray data in blue and optical data in white of DEM L238 and DEM L249, two supernova remnants in the Large Magellanic Cloud. The inset reveals how DEM L238 (shown on the right in the wide-field view) appears in the three bands of X-ray emission, where low energy X-rays are shown in red, medium energies in green and high energies in blue. The central region of DEM L238 is green which indicates that it is rich in iron. This overabundance of iron identifies this object as a Type Ia supernova, possibly as a result from the explosion of a much younger star than expected.........

Posted by: Brooke      Read more         Source

December 28, 2006, 9:55 PM CT

Glow of Universe's First Objects

New observations from NASA's Spitzer Space Telescope strongly suggest that infrared light detected in a prior study originated from clumps of the very first objects of the universe. The recent data indicate this patchy light is splattered across the entire sky and comes from clusters of bright, monstrous objects more than 13 billion light-years away.

"We are pushing our telescopes to the limit and are tantalizingly close to getting a clear picture of the very first collections of objects," said Dr. Alexander Kashlinsky of NASA's Goddard Space Flight Center, Greenbelt, Md., lead author on two reports to appear in the Astrophysical Journal Letters. "Whatever these objects are, they are intrinsically incredibly bright and very different from anything in existence today".

Astronomers believe the objects are either the first stars -- humongous stars more than 1,000 times the mass of our sun -- or voracious black holes that are consuming gas and spilling out tons of energy. If the objects are stars, then the observed clusters might be the first mini-galaxies containing a mass of less than about one million suns. The Milky Way galaxy holds the equivalent of approximately 100 billion suns and was probably created when mini-galaxies like these merged.

This study is a thorough follow-up to an initial observation presented in Nature in November 2005 by Kashlinksy and his team. The new analysis covered five sky regions and involved hundreds of hours of observation time.........

Posted by: Brooke      Read more         Source

December 18, 2006, 8:57 PM CT

The Frozen Secrets Of Comet Wild 2

Eleven months ago, NASA's Stardust mission touched down in the Utah desert with the first solid comet samples ever retrieved from space. Since then, nearly 200 scientists from around the globe have studied the minuscule grains, looking for clues to the physical and chemical history of our solar system. Although years of work remain to fully decipher the secrets of comet Wild 2, researchers are sure that it contains some of the most primitive and exotic chemical structures ever studied in a laboratory.

Preliminary results appear in a special section of the December 15 issue of Science. Overall, research efforts have focused on answering "big-picture" questions regarding the nature of the comet samples that were returned, including determining mineral structures, chemical composition, and the chemistry of the organic, or carbon-containing, compounds they carry. Carnegie researchers made key contributions to the latter effort. Out of seven papers in total, four involved Carnegie scientists from the Geophysical Laboratory (GL) and the Department of Terrestrial Magnetism (DTM).

"Carnegie enjoys a unique concentration of instrumentation and expertise to be able to engage in cutting-edge questions such as those posed by the Stardust mission," said GL's Andrew Steele.........

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December 13, 2006, 4:30 AM CT

Tall Mountains on Titan

The infrared-sensitive camera on NASA's Cassini spacecraft has photographed the tallest mountains ever seen on Saturn's moon, Titan.

The mountain chain is nearly a mile high (1.5 kilometers), 93 miles long (150 kilometers) and 19 miles wide (30 kilometers). The mountains are topped by bright, white material which may be methane or other organic (carbon-containing) "snow".

"We see a massive mountain range that reminds me of the Sierra Nevada in the western United States," said Cassini scientist Robert H. Brown of the University of Arizona Lunar and Planetary Laboratory in Tucson. Brown is head of Cassini's visual and infrared mapping spectrometer (VIMS), which imaged the mountains in Titan's southern hemisphere during the Oct. 25, 2006 flyby.

The camera took its highest-resolution infrared views of Titan ever during this flyby, resolving surface features as small as 400 meters, or about 440 yards. Other features seen in the high-resolution VIMS images include fields of dunes and a deposit that resembles a volcanic flow.

If Titan were Earth, the mountains would be at latitudes near New Zealand. They probably formed as mid-ocean ridges form on Earth: The surface crust pulls apart, and material beneath the crust wells up through the crack, creating a ridge.........

Posted by: Brooke      Permalink         Source