July 3, 2008, 9:21 PM CT

Einstein's Theory Passes Strict, New Test

Taking advantage of a unique cosmic configuration, astronomers have measured an effect predicted by Albert Einstein's theory of General Relativity in the extremely strong gravity of a pair of superdense neutron stars. Essentially, the famed physicist's 93-year-old theory passed yet another test.

Researchers at McGill University used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to do a four-year study of a double-star system unlike any other known in the Universe. The system is a pair of neutron stars, both of which are seen as pulsars that emit lighthouse-like beams of radio waves.

"Of about 1700 known pulsars, this is the only case in which two pulsars orbit around each other," said Rene Breton, a graduate student at McGill University in Montreal, Canada. In addition, the stars' orbital plane is aligned nearly perfectly with their line of sight to the Earth. This causes the signal of one to be blocked, or eclipsed, as it circles the other.

"Those eclipses are the key to making a measurement that could never be done before," Breton said.

Einstein's 1915 theory predicted that in a close system of two very massive objects, such as neutron stars, one object's gravitational tug, along with an effect of its spinning around its axis, should cause the spin axis of the other to wobble, or precess......... Posted by: Sean      Read more         Source

June 18, 2008, 8:51 PM CT

Newly Born Twin Stars Are Far From Identical

Two stars, each with the same mass and in orbit around each other, are twins that one would expect to be identical. So astronomers were surprised when they discovered that twin stars in the Orion Nebula, a well-known stellar nursery 1,500 light years away, were not identical at all. In fact, these stars exhibited significant differences in brightness, surface temperature and possibly even size.

The study, which is reported in the June 19 issue of the journal Nature, suggests that one of the stars formed significantly earlier than its twin. Because astrophysicists have assumed that binary stars form simultaneously, the discovery provides an important new challenge for today's star formation theories, forcing theorists to reexamine their models to see if the models can indeed produce binaries with stars that form at different times.

Because mass and age estimates for stars less than a few million years old are based on models that were calibrated with measurements of binary stars presumed to have formed simultaneously, this new discovery may cause astronomers to readjust their estimates for thousands of young stars.

The newly formed twin stars are about 1 million years old. With a full lifespan of about 50 billion years, that makes them equivalent to one-day-old human babies......... Posted by: Sean      Read more         Source

June 4, 2008, 10:41 PM CT

Making A Giant Lunar Telescopes

Researchers working at NASA's Goddard Space Flight Center in Greenbelt, Md., have concocted an innovative recipe for giant telescope mirrors on the Moon. To make a mirror that dwarfs anything on Earth, just take a little bit of carbon, throw in some epoxy, and add lots of lunar dust.

"We could make huge telescopes on the moon relatively easily, and avoid the large expense of transporting a large mirror from Earth," says Peter Chen of NASA Goddard and the Catholic University of America, which is located in Washington, D.C. "Since most of the materials are already there in the form of dust, you don't have to bring very much stuff with you, and that saves a ton of money."

Chen and his Goddard colleagues Douglas Rabin, Michael Van Steenberg, and Ron Oliversen are presenting their mirror-making technique in a poster at the 212th meeting of the American Astronomical Society in St. Louis, Mo. They will also describe their results in a press conference on Wednesday, June 4 at 9:30 a.m. CDT.

For years, Chen had been working with carbon-fiber composite materials to produce high-quality telescope mirrors. But Chen and colleagues decided to try an experiment. They substituted carbon nanotubes (tiny tubular structures made of pure carbon) for the carbon-fiber composites. When they mixed small amounts of carbon nanotubes and epoxies (glue-like materials) with crushed rock that has the same composition and grain size as lunar dust, they discovered to their surprise that they had created a very strong material with the consistency of concrete. This material can be used instead of glass to make mirrors......... Posted by: Sean      Read more         Source

May 27, 2008, 10:19 PM CT

The Little Man and the Cosmic Cauldron

On the occasion of the 10th anniversary of the Very Large Telescope's First Light, ESO is releasing two stunning images of different kinds of nebulae, located towards the Carina constellation. The first one, Eta Carinae, has the shape of a 'little man' and surrounds a star doomed to explode within the next 100 000 years. The second image features a much larger nebula, whose internal turmoil is created by a cluster of young, massive stars.

Being brighter than one million Suns, Eta Carinae is the most luminous star known in the Galaxy. It is the closest example of a luminous blue variable, the last phase in the life of a very massive star before it explodes in a fiery supernova.

Eta Carinae is surrounded by an expanding bipolar cloud of dust and gas known as the Homunculus ('little man' in Latin), which astronomers believe was expelled from the star during a great outburst seen in 1843 [1].

Eta Carinae was one of the first objects to be imaged during First Light with ESO's VLT, 10 years ago. At the time, the image obtained with a test camera already showed the unique capabilities of the European flagship telescope for ground-based optical and infrared astronomy, as well as of its unique location on the mountain of Paranal. The image had a resolution of 0.38 arcseconds......... Posted by: Sean      Read more         Source

May 27, 2008, 10:16 PM CT

Seeking Answers To Asteroid Deflection

An Asteroid Deflection Research Center (ADRC) has been established on the Iowa State campus to bring scientists from around the world to develop asteroid deflection technologies. The center was signed into effect in April by the Office of the Executive Vice President and Provost.

"In the early part of 1990s, researchers around the world initiated studies to assess and devise methods to prevent near-Earth objects from striking Earth," said Bong Wie, the Vance D. Coffman Chair Professor in Aerospace Engineering and director of the center. "However, it is now 2008, and there is no consensus on how to reliably deflect them in a timely manner," he noted.

Wie, whose research expertise includes space vehicle dynamics and control, modeling and control of large space structures, and solar sail flight control system development and mission design, joined the Iowa State faculty last August. "I am very happy that Professor Bong Wie has joined the faculty at ISU," said Elizabeth Hoffman, executive vice president and provost. "His work on asteroid deflection is exciting and of great importance."

The ADRC will host an International Symposium on Asteroid Deflection Technology in fall 2008. Researchers and engineers from NASA, the European Space Agency, academia, and the aerospace industry will be invited to the Iowa State campus to formulate a roadmap for developing asteroid deflection technologies......... Posted by: Sean      Read more         Source

May 21, 2008, 9:50 PM CT

Why do astronauts suffer from space sickness?

Rotating astronauts for a lengthy period provided researcher Suzanne Nooij with better insight into how 'space sickness' develops, the nausea and disorientation experienced by a number of astronauts. Nooij will receive her PhD from TU Delft on this subject on Tuesday 20 May.

Gravity plays a major role in our spatial orientation. Changes in gravitational forces, such as the transition to weightlessness during a space voyage, influence our spatial orientation and require adaptation by a number of of the physiological processes in which our balance system plays a part. As long as this adaptation is incomplete, this can be coupled to motion sickness (nausea), visual illusions and disorientation.

This 'space sickness' or Space Adaptation Syndrome (SAS), is experienced by about half of all astronauts during the first few days of their space voyage. Wubbo Ockels, the first Dutchman in space in 1986, also suffered from these symptoms. In his capacity as TU Delft professor, Ockels is PhD supervisor for Suzanne Nooij's research.

Rotation.

Interestingly, SAS symptoms can even be experienced after lengthy exposure to high gravitational forces in a human centrifuge, as is used for instance for testing and training fighter pilots. To experience this, people have to spend longer than an hour in a centrifuge and be subjected to gravitational forces of three times higher than that on Earth. The rotation is in itself not unpleasant, but after leaving the centrifuge about half of the test subjects experience the same symptoms as caused by space sickness. It also turns out that astronauts who suffer from space sickness during space flights also experience these symptoms following lengthy rotation on Earth. This means that these symptoms are not caused by weightlessness as such, but more generally by adaptation to a different gravitational force......... Posted by: Sean      Read more         Source

May 21, 2008, 8:45 PM CT

Storm Winds Blow in Jupiter's Little Red Spot

Using data from NASA's New Horizons spacecraft and two telescopes at Earth, an international team of researchers has observed that one of the solar system's largest and newest storms - Jupiter's Little Red Spot - has some of the highest wind speeds ever detected on any planet.

The New Horizons scientists combined observations from their Pluto-bound spacecraft, which flew past Jupiter in February 2007; data from the Hubble Space Telescope orbiting Earth, and the European Southern Observatory's Very Large Telescope, perched on an Atacama Desert mountain in Chile. This is the first time that high resolution, close-up imaging of the Little Red Spot has been combined with powerful Earth-orbital and ground-based imagery made at ultraviolet through mid-infrared wavelengths.

Jupiter's "LRS" is an anticyclone, a storm whose winds circulate in the opposite direction to that of a cyclone - counterclockwise, in this case. It is nearly the size of Earth and as red as the similar, but larger and more well known, Great Red Spot (or GRS). The dramatic evolution of the LRS began with the merger of three smaller white storms that had been observed since the 1930s. Two of these storms coalesced in 1998, and the combined pair merged with a third major Jovian storm in 2000. In late 2005 - for reasons still unknown - the combined storm turned red......... Posted by: Sean      Read more         Source

May 19, 2008, 8:21 PM CT

Common star draws swift attention with unprecedented flare

On April 25, one of our nearest stellar neighbors, a small, faint red dwarf known as EV Lacertae, unleashed the brightest flare ever detected from a normal star outside our solar system. The monster blast of radiation was picked up with NASA's Swift satellite, which scans space looking for Gamma-ray bursts coming from the edge of the universe.

"The sheer magnitude of this stellar flare is unprecedented, and it was produced in our own celestial back yard by a star of the most common type," said Rachel Osten, a Hubble Fellow at the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md.

Though EV Lacertae is only 16 light-years from Earth, it's not visible in the night sky. It is much cooler than the sun and shines with only one percent of the sun's light. The star's faint magnitude-10 glow is far below naked-eye visibility. However, the flare, which packed the power of thousands of solar flares, would have made it easy to see EV Lacertae had it occurred when the star was observably positioned in the night sky.

It's in the Spin

As per Osten, who studies nearby stars, EV Lacertae is young, with an estimated age of some 300 hundred million years, and small with a mass and diameter only about a third that of the sun. However, it rotates much faster than the sun, completing a rotation once every four days compared with every four weeks for the sun......... Posted by: Sean      Read more         Source

May 18, 2008, 10:13 PM CT

Dusty Galaxies

Anyone gazing up on a dark clear night is greeted by the spectacle of thousands of powerful fusion reactors - the stars. These balls of extremely hot gas are generating unimaginably large quantities of energy. Even the stars within a cube of "only" one light year on a side, taken at a random position in the universe, generate on average 40 quadrillion kilowatthours in one year. This would be enough to meet the current energy consumption needs of mankind 300 times over. Even so, it now appears that from our vantage point we are only registering about half the total energy released by stars in our part of the universe; the other half is being absorbed by miniscule particles of dust floating in the vast expanses of interstellar space within galaxies. This is the conclusion reached by a team of astrophysicists from institutes around the world, including the Max Planck Institute for Nuclear Physics in Heidelberg. The results have implications for our understanding of the creation and evolution of galaxies through cosmic history (The Astrophysical Journal, 10 May 2008).

Galaxies are gigantic systems containing billions of stars bound together by gravity.

Our sun is one of around 200 billion stars in the Milky Way, which is a typical example of one such system. If we could view the Milky Way from the outside, the combined light from the stars would appear like a giant Catherine wheel. Since almost all stars are located within galaxies, and since in any case stars become too faint to be detected individually if they are too far away, the total light emitted by galaxies has to be investigated in order to measure the total energy output from stars in the universe......... Posted by: Sean      Read more         Source

May 18, 2008, 10:01 PM CT

Laser May Aid Searches for Earthlike Planets

Researchers at the University of Konstanz (Gera number of) and the National Institute of Standards and Technology (NIST) have demonstrated an ultrafast laser that offers a record combination of high speed, short pulses and high average power. The new laser is expected to have a range of applications from gas sensors to communications, but in particular, say researchers, it could boost the sensitivity of astronomical tools searching for other Earthlike planets as much as 100 fold.

The dime-sized laser, described last week at the Conference on Lasers and Electro-Optics,* emits 10 billion pulses per second, each lasting about 40 femtoseconds (quadrillionths of a second). The short, fast pulses make it ideal for use as a "frequency comb"-an ultraprecise technique for measuring frequencies of light. It is 10 times faster than a standard NIST frequency comb, produces much shorter pulses than comparable lasers, and is 100 to 1000 times more powerful than typical high-speed lasers, producing clearer signals in experiments. It was built by Albrecht Bartels at the Center for Applied Photonics of the University of Konstanz in Gera number of.

As a frequency comb the laser could sharpen the search for planets orbiting distant stars. Astronomers look for slight variations in the apparent colors of starlight over time that are caused by the star wobbling from the gravitational pull of an orbiting planet. The effect is very subtle, and astronomers are limited by the frequency standards they use to calibrate their instruments. Frequency combs could be such superior calibration tools that they would make it possible to detect even tiny Earthlike planets that cause color shifts equivalent to a star wobble of just a few centimeters per second. Current instruments can detect-at best-a wobble of about 1 meter per second......... Posted by: Sean      Read more         Source