January 3, 2008, 8:39 PM CT

Stardust formed close to sun

Samples of the material picked up during the NASA Stardust mission indicate that parts of the comet Wild 2 actually formed in an area close to the sun.

New research by an international collaboration including Livermore researcher Saša Bajt analyzed noble gases within Stardust samples.The helium and neon isotope analysis suggests that some of the Stardust grains match a special type of carbonaceous material found in meterorites; hence both must have spent time in the same gas reservoir, which was close to the sun.

About 10 percent of the mass of Wild 2 is estimated to be from particles transported out from hot inner zones to the cold zone where Wild 2 formed. The paper concludes that this is how these grains with unusual isotope ratios go incorporated into a comet.

Earlier research showed that the comet formed in the Kuiper Belt, outside the orbit of Neptune, and only recently entered the inner regions of the solar system.

Wild 2 spent most of its life orbiting in the Kuiper Belt, far beyond Neptune, and in 1974 had a close encounter with Jupiter that placed it into its current orbit. The Stardust spacecraft's seven-year mission returned to earth in January 2006 with particles that are the same material that accreted along with ice to shape the comet about 4.57 billion years ago, when the sun and planets formed......... Posted by: Sean      Read more         Source

January 2, 2008, 10:42 PM CT

More data in search of extraterrestrial intelligence

The longest-running search for radio signals from alien civilizations is getting a burst of new data from an upgraded Arecibo telescope, which means the SETI@home project needs more desktop computers to help crunch the data.

Since SETI@home launched eight years ago, the project based at the University of California, Berkeley's Space Sciences Laboratory has signed up more than 5 million interested volunteers and boasts the largest community of dedicated users of any Internet computing project: 170,000 devotees on 320,000 computers.

Yet, new and more sensitive receivers on the world's largest radio telescope in Arecibo, Puerto Rico, and better frequency coverage are generating 500 times more data for the project than before. The SETI@home software has been upgraded to deal with this new data as the search for extraterrestrial intelligence (SETI) enters a new era and offers a new opportunity for those who want to help find other civilizations in the universe.

"The next generation SETI@home is 500 times more powerful then anything anyone has done before," said project chief scientist Dan Werthimer. "That means we are 500 times more likely to find ET than with the original SETI@home".

As per project scientist Eric Korpela, the new data amounts to 300 gigabytes per day, or 100 terabytes (100,000 gigabytes) per year, about the amount of data stored in the U.S. Library of Congress. "That's why we need all the volunteers," he said. "Everyone has a chance to be part of the largest public participation science project in history"......... Posted by: Sean      Read more         Source

January 2, 2008, 10:36 PM CT

White Dwarf Pulses Like a Pulsar

New observations from Suzaku, a joint Japanese Aerospace Exploration Agency (JAXA) and NASA X-ray observatory, have challenged scientists' conventional understanding of white dwarfs. Observers had believed white dwarfs were inert stellar corpses that slowly cool and fade away, but the new data tell a completely different story.

At least one white dwarf, known as AE Aquarii, emits pulses of high-energy (hard) X-rays as it whirls around on its axis. "We're seeing behavior like the pulsar in the Crab Nebula, but we're seeing it in a white dwarf," says Koji Mukai of NASA Goddard Space Flight Center in Greenbelt, Md. The Crab Nebula is the shattered remnant of a massive star that ended its life in a supernova explosion. "This is the first time such pulsar-like behavior has ever been observed in a white dwarf." Mukai is co-author of a paper presented at a Suzaku science conference in San Diego, Calif., in December.

White dwarfs and pulsars represent distinct classes of compact objects that are born in the wake of stellar death. A white dwarf forms when a star similar in mass to our sun runs out of nuclear fuel. As the outer layers puff off into space, the core gravitationally contracts into a sphere about the size of Earth, but with roughly the mass of our sun. The white dwarf starts off scorching hot from the star's residual heat. But with nothing to sustain nuclear reactions, it slowly cools over billions of years, eventually fading to near invisibility as a black dwarf......... Posted by: Sean      Read more         Source

December 27, 2007, 9:10 AM CT

Polarization technique focuses limelight

An international team of astronomers, led by Professor Svetlana Berdyugina of ETH Zurichs Institute of Astronomy, has for the first time ever been able to detect and monitor the visible light that is scattered in the atmosphere of an exoplanet. Employing techniques similar to how Polaroid sunglasses filter away reflected sunlight to reduce glare, the team of researchers were able to extract polarized light to enhance the faint reflected starlight glare from an exoplanet. As a result, the researchers could infer the size of its swollen atmosphere. They also directly traced the orbit of the planet, a feat of visualization not possible using indirect methods.

Hot Jupiter

The transiting exoplanet under study circles the dwarf star HD189733 in the constellation Vulpecula and lies more than 60 light years from the earth. Known as HD189733b, this exoplanet was discovered two years ago via Doppler spec-troscopy. HD189733b is so close to its parent star that its atmosphere expands from the heat. Until now, astronomers have never seen light reflected from an exoplanet, eventhough they have deduced from other observations that HD189733b probably resembles a hot Jupiter a planet orbiting extremely closely to its parent star. Unlike Jupiter, however, HD189733b orbits its star in a couple of days rather than the 12 years it takes Jupiter to make one orbit of the sun......... Posted by: Sean      Read more         Source

December 20, 2007, 9:54 PM CT

Anatomy of a cosmic bird

Using ESO's Very Large Telescope, an international team of astronomers [1] has discovered a stunning rare case of a triple merger of galaxies. This system, which astronomers have dubbed 'The Bird' - albeit it also bears resemblance with a cosmic Tinker Bell - is composed of two massive spiral galaxies and a third irregular galaxy.

The galaxy ESO 593-IG 008, or IRAS 19115-2124, was previously merely known as an interacting pair of galaxies at a distance of 650 million light-years. But surprises were revealed by observations made with the NACO instrument attached to ESO's VLT, which peered through the all-pervasive dust clouds, using adaptive optics to resolve the finest details [2].

Underneath the chaotic appearance of the optical Hubble images - retrieved from the Hubble Space Telescope archive - the NACO images show two unmistakable galaxies, one a barred spiral while the other is more irregular.

The surprise lay in the clear identification of a third, clearly separate component, an irregular, yet fairly massive galaxy that seems to be forming stars at a frantic rate.

"Examples of mergers of three galaxies of roughly similar sizes are rare," says Petri Visnen, lead author of the paper reporting the results. "Only the near-infrared VLT observations made it possible to identify the triple merger nature of the system in this case"......... Posted by: Sean      Read more         Source

December 20, 2007, 9:43 PM CT

COROT surprises a year after launch

The space-borne telescope, COROT (Convection, Rotation and planetary Transits), has just completed its first year in orbit. The observatory has brought in surprises after over 300 days of scientific observations.

Pioneering precision measurement over long periods of time COROT is observing a large number of stars, up to 12 000, simultaneously, at a very high precision - unprecedented in ground-based astronomy. The key to the high-precision is that the observations can be carried out over very long periods of time - up to 150 days. This is being done for the first time ever.

The satellite measures variations in the light output of these stars down to one part in a million. This level of precision allows researchers to study the a number of ways in which stars vary. The pulsations are caused either due to unknown physical processes in the stellar interior, or by objects such as planets passing in front of the stellar surface.

A treasure trove of information for stellar seismology

To date, 30 stars have been observed as part of the study of stellar seismology, the study of the miniscule changes in light output from a star caused by acoustic waves travelling through the star. The pattern of the changes tells us a lot about what is happening deep inside the star. The stars observed by COROT range from objects similar to our own Sun to older or more massive stars. The observation period varies between 20 and 150 days of essentially uninterrupted study......... Posted by: Sean      Read more         Source

December 18, 2007, 9:55 PM CT

Sandia supercomputers offer new explanation

The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.

"The asteroid that caused the extensive damage was much smaller than we had thought," says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. "That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed".

Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, "We should be making more efforts at detecting the smaller ones than we have till now".

The new simulation - which more closely matches the widely known facts of destruction than earlier models - shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.

This causes stronger blast waves and thermal radiation pulses at the surface than would be predicted by an explosion limited to the height at which the blast was initiated......... Posted by: Sean      Read more         Source

December 18, 2007, 9:45 PM CT

'Shot in the Dark' Star Explosion Stuns Astronomers

A team of astronomers has discovered a cosmic explosion that seems to have come from the middle of nowhere - thousands of light-years from the nearest galaxy-sized collection of stars, gas, and dust. This "shot in the dark" is surprising because the type of explosion, a long-duration gamma-ray burst (GRB), is believed to be powered by the death of a massive star.

"Here we have this very bright burst, yet it's surrounded by darkness on all sides," says Brad Cenko of the California Institute of Technology, Pasadena, Calif., lead author of the team's paper, which has been accepted for publication in The Astrophysical Journal. "The nearest galaxy is more than 88,000 light-years away, and there's almost no gas lying between the burst and Earth."

The blast was detected on January 25, 2007, by several spacecraft of the Inter-Planetary Network. Observations by NASA's Swift satellite pinpointed the explosion, named GRB 070125 for its detection date, to a region of sky in the constellation Gemini. It was one of the brightest bursts of the year, and the Caltech/Penn State team moved quickly to observe the burst's location with ground-based telescopes.

Using the team's robotic 60-inch telescope at Palomar Observatory in Calif., the astronomers discovered that the burst had a bright and fast-fading afterglow in visible light. This prompted them to observe the afterglow in detail with two of the world's largest telescopes, the 8-meter Gemini North telescope and 10-meter Keck I telescope, both near the summit of Hawaii's Mauna Kea......... Posted by: Sean      Read more         Source

December 18, 2007, 8:40 PM CT

Mission heads for comet Hartley 2

NASA has given a University of Maryland-led team of researchers the green light to fly the Deep Impact spacecraft to Comet Hartley 2 on a two-part extended mission known as EPOXI. The spacecraft will fly by Earth on New Years Eve at the beginning of a more than two-and-a-half-year journey to Hartley 2.

The EPOXI mission is actually two new missions in one. During the first six months of the journey to Hartley 2, the Extrasolar Planet Observations and Characterization (EPOCh) mission will use the larger of the two telescopes on the Deep Impact spacecraft to search for Earth-sized planets around five stars selected as likely candidates for such planets. Upon arriving at the comet the Deep Impact eXtended Investigation (DIXI) mission will conduct an extended flyby of Hartley 2 using all three of the spacecrafts instruments (two telescopes with digital color cameras and an infrared spectrometer).

"It's exciting that we can send the Deep Impact spacecraft on a new mission that combines two totally independent science investigations, both of which can help us better understand how solar systems form and evolve," said Deep Impact leader and University of Maryland astronomer Michael A'Hearn, who is principal investigator (PI) for both the overall EPOXI mission and its DIXI component......... Posted by: Sean      Read more         Source

December 17, 2007, 9:07 PM CT

Ambitious Lunar Mission

MIT will lead a $375 million mission to map the moon's interior and reconstruct its thermal history, NASA announced this week.

The Gravity Recovery and Interior Laboratory (GRAIL) mission will be led by MIT professor Maria Zuber and will be launched in 2011. It will put two separate satellites into orbit around the moon to precisely map variations in the moon's gravitational pull. These changes will reveal differences in density of the moon's crust and mantle, and can be used to answer fundamental questions about the moon's internal structure and its history of collisions with asteroids.

The detailed information about lunar gravity will also significantly facilitate any future manned or unmanned missions to land on the moon. Such data will be used to program the descent to the surface to avoid a crash landing and will also help target desirable landing sites. Moreover, the mission's novel technology could eventually be used to explore other interesting worlds such as Mars.

"After the three-month mission is completed, we will know the lunar gravitational field better than we know Earth's," says Zuber, who is head of MIT's Department of Earth, Atmospheric and Planetary Sciences and the E.A. Griswold Professor of Geophysics. She will be the principal investigator for the GRAIL mission......... Posted by: Sean      Read more         Source