Mysterious Energy Burst Stuns Astronomers

Source:

http://www.sciencedaily.com/releases/2007/09/070928101200.htm

Science Daily — In a shock finding, astronomers using CSIRO’s Parkes telescope have detected a huge burst of radio energy from the distant universe that could open up a new field in astrophysics.

The research team, led by Assistant Professor Duncan Lorimer of West Virginia University, reported its discovery in the journal Science Express.
The radio burst appears to have originated at least one-and-a-half billion light-years [500 Mpc] away but was startlingly strong.
“Normally the kind of cosmic activity we’re looking for at this distance would be very faint but this was so bright that it saturated the equipment,” said Professor Matthew Bailes of Swinburne University in Melbourne.
The burst was so bright that at the time it was first recorded it was dismissed as man-made radio interference. It put out a huge amount of power (10exp33 Joules), equivalent to a large (2000MW) power station running for two billion billion years.
“The burst may have been produced by an exotic event such as the collision of two neutron stars or be the last gasp of a black hole as it evaporates completely,” Professor Lorimer said.
The burst lasted just five milliseconds.
It was found by David Narkevik, an undergraduate at the West Virginia University, when he re-analysed data taken with the Parkes telescope six years ago.
Although they’ve found only one burst, the astronomers can estimate how often they occur.
“We’d expect to see a few bursts over the whole sky every day,” said Dr John Reynolds, Officer in Charge at CSIRO’s Parkes Observatory.
“A new telescope being built in Western Australia will be ideal for finding more of these rare, transient events.
”The Australian SKA Pathfinder, which is going to be built by 2012, will have a very wide field of view—be able to see a very large piece of sky—which is exactly what you want for this kind of work,” he said.
Meanwhile, the researchers will comb archived data from the Parkes telescope for more radio bursts.
The discovery of the radio burst is similar to the discovery of gamma-ray bursts in the 1970s, when military satellites revealed flashes of gamma-rays appearing all over the sky. One kind—the so-called long-period bursts—was eventually identified as the explosion (supernova) of a massive star with the associated formation of a black hole.
Note: This story has been adapted from a news release issued by CSIRO Australia.

Fausto Intilla

www.oloscience.com

NASA Spacecraft Is A 'Go' For Asteroid Belt

Source:

http://www.sciencedaily.com/releases/2007/09/070926173729.htm

Science Daily — Launch and flight teams are in final preparations for the planned Sept. 27 liftoff from Pad 17-B at Cape Canaveral Air Force Station, Fla., of NASA's Dawn mission. The Dawn spacecraft will venture into the heart of the asteroid belt, where it will document in exceptional detail the mammoth rocky asteroid Vesta, and then, the even bigger icy dwarf planet Ceres.

"If you live in the Bahamas this is one time you can tell your neighbor, with a straight face, that Dawn will rise in the west," said Dawn Project Manager Keyur Patel of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Weather permitting, we are go for launch Thursday morning -- a little after dawn."
Dawn's Sept. 27 launch window is 7:20 to 7:49 a.m. Eastern Daylight Time (4:20 to 4:49 a.m. Pacific Daylight Time). At the moment of liftoff, the Delta II's first-stage main engine along with six of its nine solid-fuel boosters will ignite. The remaining three solids are ignited in flight following the burnout of the first six. The first-stage main engine will burn for 4.4 minutes. The second stage will deposit Dawn in a 185-kilometer-high (100- nautical-mile) circular parking orbit in just under nine minutes. At about 56 minutes after launch, the rocket's third and final stage will ignite for approximately 87 seconds. When the third stage burns out, actuators and push-off springs on the launch vehicle will separate the spacecraft from the third stage.
"After separation, the spacecraft will go through an automatic activating sequence, including stabilizing the spacecraft, activating flight systems and deploying Dawn's two massive solar arrays," said Patel. "Then and only then will the spacecraft energize its transmitter and contact Earth. We expect acquisition of signal to occur anywhere from one-and-a-half hours to three-and-a-half hours after launch."
The Dawn mission will explore Vesta, and later Ceres, because these two asteroid belt behemoths have been witness to so much of our solar system's history.
"Visiting both Vesta and Ceres enables a study in extraterrestrial contrasts," said Dawn Principal Investigator Christopher Russell of the University of California, Los Angeles. "One is rocky and is representative of the building blocks that constructed the planets of the inner solar system. The other may very well be icy and represents the outer planets. Yet, these two very diverse bodies reside in essentially the same neighborhood. It is one of the mysteries Dawn hopes to solve."
Using the same spacecraft to reconnoiter two different celestial targets makes more than fiscal sense. It makes scientific sense. By utilizing the same set of instruments at two separate destinations, scientists can more accurately formulate comparisons and contrasts. Dawn's science instrument suite will measure mass, shape, surface topography and tectonic history, elemental and mineral composition, as well as seek out water-bearing minerals. In addition, the Dawn spacecraft itself and the way it orbits both Vesta and Ceres will be used to measure the celestial bodies' gravity fields.
"Understanding conditions that lead to the formation of planets is a goal of NASA's mission of exploration," said David Lindstrom, Dawn program scientist at NASA Headquarters, Washington. "The science returned from Vesta and Ceres could unlock many of the mysteries of the formation of the rocky planets including Earth."
Before all this celestial mystery unlocking can occur, Dawn has to reach the asteroid belt and its first target – Vesta. This is a four-year process that begins with launch and continues with the firing of three of the most efficient engines in NASA's space motor inventory - ion propulsion engines. Employing a complex commingling of solar-derived electric power and xenon gas, these frugal powerhouses must fire for months at a time to propel as well as steer Dawn. Over their eight-year, almost 4-billion-mile lifetime, these three ion propulsion engines will fire cumulatively for about 50,000 hours (over five years) - a record for spacecraft.
The Dawn mission to asteroid Vesta and dwarf planet Ceres is managed by JPL, for NASA's Science Mission Directorate, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena. The University of California, Los Angeles, is responsible for overall Dawn mission science. Other scientific partners include: Los Alamos National Laboratory, New Mexico; Max Planck Institute for Solar System Research, Katlenburg, Germany; and Italian National Institute of Astrophysics, Rome. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.
Note: This story has been adapted from a news release issued by NASA/ Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Baby Booms And Birth Control In Space

Source:

http://www.sciencedaily.com/releases/2007/09/070925092520.htm

Science Daily — Stars in galaxies are a bit similar to people: during the first phase of their existence they grow rapidly, after which a stellar birth control occurs in most galaxies.

New observations from Dutch astronomer Mariska Kriek with the Gemini Telescope on Hawaii and the Very Large Telescope (VLT) in Chile, have shown that a part of the heavy galaxies already stopped forming stars when the universe was still a toddler, about 3 billion years old. Astronomers suspect that black holes exert an influence on this halt in births.
Heavy galaxies are a boring phenomenon in the modern universe. They have an elliptical or a round form, the stars are evenly distributed over the galaxies and no more new stars are formed.
The large quantities of stars, about 10 billion, and the current, low birth rate point to the fact that star formation must have been much higher in the past. When were these stars formed and why did the star formation subsequently stop?
Black holes as a birth control measure
The finite speed of light makes it possible to study the universe when it was much younger than now. With the help of spectrographs, such as the Gemini Near-InfraRed Spectrograph and SINFONI on the VLT, Mariska Kriek and her colleagues studied 36 heavy galaxies in the early universe.
These galaxies are so far away that the light from them has taken 11 billion years to reach us. Interestingly the researchers found no signs of star formation for a large proportion of the galaxies observed. This new discovery contributes to the growing mass of evidence that the formation of new stars in heavy galaxies is strongly inhibited after an explosive baby boom.
This 'halt in births' is possibly due to the influence of the enormous black holes in the middle of the galaxies. The large amount of material attracted by these black holes generates enormous quantities of energy that subsequently heats up the gas in the galaxy.
As a result of this heating the gas is no longer able to form new stars. The researchers did indeed discover a black hole in a number of the galaxies they investigated. These were mainly the galaxies where the star formation was inhibited less than 1 billion years ago. These results support the idea that black holes limit the birth of new stars.
Note: This story has been adapted from a news release issued by Netherlands Organization for Scientific Research.

Fausto Intilla

www.oloscience.com

Cornucopia Of Earth-sized Planets Modeled By NASA

Source:

http://www.sciencedaily.com/releases/2007/09/070924132510.htm

Science Daily — In the Star Wars movies fictional planets are covered with forests, oceans, deserts, and volcanoes. But new models from a team of MIT, NASA, and Carnegie scientists begin to describe an even wider range of Earth-size planets that astronomers might actually be able to find in the near future.

Sara Seager, Massachusetts Institute of Technology, Cambridge, Mass.; Marc Kuchner, NASA Goddard Space Flight Center, Greenbelt, Md.; Catherine Hier-Majumder, Carnegie Institution of Washington, (deceased); and Burkhard Militzer, Carnegie, have created models for 14 different types of solid planets that might exist in our galaxy.
The 14 types have various compositions, and the team calculated how large each planet would be for a given mass. Some are pure water ice, carbon, iron, silicate, carbon monoxide, and silicon carbide; others are mixtures of these various compounds.
"We’re thinking seriously about the different kinds of roughly Earth-size planets that might be out there, like George Lucas, but for real," says Kuchner.
The team took a different approach from previous studies. Rather than assume that planets around other stars are scaled-up or scaled-down versions of the planets in our solar system, they considered all types of planets that might be possible, given what astronomers know about the composition of protoplanetary disks around young stars.
"We have learned that extrasolar giant planets often differ tremendously from the worlds in our solar system, so we let our imaginations run wild and tried to cover all the bases with our models of smaller planets," says Kuchner. "We can make educated guesses about where these different kinds of planets might be found. For example, carbon planets and carbon-monoxide planets might favor evolved stars such as white dwarfs and pulsars, or they might form in carbon-rich disks like the one around the star Beta Pictoris. But ultimately, we need observations to give us the answers."
The team calculated how gravity would compress planets of varying compositions. The resulting computer models predict a planet’s diameter for a given composition and mass. For example, a 1-Earth-mass planet made of pure water will be about 9,500 miles across, whereas an iron planet with the same mass will be only about 3,000 miles in diameter. For comparison, Earth, which is made mostly of silicates, is 7,926 miles across at its equator.
Some of the results were expected, such as the fact that pure water planets (similar to the moons of the outer planets in our solar system, which consist mostly of water ice) were the least dense of the solid planets, and pure iron planets are the most dense. But there were some surprises. The team discovered that no matter what material a planet is made of, the mass/diameter relationship follows a similar pattern.
"All materials compress in a similar way because of the structure of solids," explains Seager. "If you squeeze a rock, nothing much happens until you reach some critical pressure, then it crushes. Planets behave the same way, but they react at different pressures depending on the composition. This is a big step forward in our fundamental understanding of planets."
The team hopes that these models will yield insights into planet compositions when astronomers start finding Earth-sized planets around other stars. Missions such as the French Corot satellite, which launched on December 27, 2006, and NASA’s Kepler spacecraft, scheduled to launch in 2009, can find planets not much larger than Earth by watching them pass in front of their host stars, events known as transits. The transits yield the planet’s size, and follow-up studies can measure the mass. By comparing a planet's size and mass, astronomers might be able to determine whether it is mostly water ice or mostly iron, for example.
But astronomers using the transit method will find it difficult at best to distinguish a silicate planet from a carbon planet, because they’re about the same size for a given mass. "To make this finer distinction, we will need some help from NASA’s James Webb Space Telescope or Terrestrial Planet Finder," says Kuchner. "With these instruments, we could take spectra of Earth-mass planets, which will tell us about their chemistries."
The team’s paper is currently scheduled to appear in the October 20 issue of the Astrophysical Journal.
Note: This story has been adapted from a news release issued by NASA Goddard Space Flight Center.

Fausto Intilla

www.oloscience.com

Some Black Holes May Not Be Black, But Rather 'Naked Singularities'

Source:

http://www.sciencedaily.com/releases/2007/09/070924151118.htm

Science Daily — Researchers from Duke University and the University of Cambridge think there is a way to determine whether some black holes are not actually black.

Finding such an unmasked form of what physicists term a singularity "would shock the foundation of general relativity," said Arlie Petters, a Duke professor of mathematics and physics who worked with Marcus Werner, Cambridge graduate student in astrophysics, on a report posted online Monday, Sept. 24, for the research journal Physical Review D.
"It would show that nature has surprises even weirder than black holes," Petters added.
Albert Einstein originally theorized that stars bigger than the sun can collapse and compress into singularities, entities so confining and massively dense that the laws of physics break down inside them.
Astronomers have since found indirect evidence for these entities, which are popularly known as black holes because of the "cosmic censorship conjecture." This conjecture is that "realistic" singularities -- meaning those that can be formed in nature -- must always hide within a barrier known as an "event horizon" from which light can never escape. That makes them appear perpetually black to the rest of the universe.
But cosmic censorship is "an open conjecture that is very difficult to prove, and very difficult to disprove," said Petters.
And, despite the general support for the universality of black holes, Kip Thorne and John Preskill, two experts in the cosmology of relativity at the California Institute of Technology, have suggested for more than a decade that naked singularities could exist in certain instances. Now Petters and Werner have devised a way to test for their presence.
Astronomers cannot say for sure whether all black holes are actually black, having never fully penetrated the obscuring outward matter surrounding such objects, Petters said. As their main evidence, scientists can only point to effects that the massive gravitational pull of certain unseen entities exert on surrounding matter. Those effects include emissions of highly energetic radiation, or the extreme orbits of nearby stars.
Petters is an expert in "gravitational lensing," another effect of relativity that permits massive sources of gravity to split light from background astronomical features into multiple images.
In earlier reports in the November, 2005 and February, 2006 issues of Physical Review D, he and Charles Keeton of Rutgers University suggested a way to use gravitational lensing to show whether cosmic censorship can ever be violated.
However, that evaluation was limited to non-spinning singularities that are considered only theoretically possible. The suspected singularities astronomers have found in space so far all appear to be rapidly spinning, sometimes at more than 1,000 times a second.
So Petters and Werner teamed up to see if they could generalize such an application of gravitational lensing to all realistic spinning singularities. Their surprising result was yes, Petters said.
In work supported by the National Science Foundation in the United States and the Science and Technology Facilities Council in the United Kingdom, the pair employed a finding that a black hole could be shed of its event horizon and become a naked singularity if its angular momentum -- an effect of its spin -- is greater than its mass.
That would translate into a spin of a few thousand rotations a second in the case of a black hole weighing about 10 times more than our Sun, said Werner.
In the event that the required conditions were met, Petters' and Werner's calculations show that a naked singularity's massive gravitation would split the light of background stars or galaxies in telltale ways that are potentially detectable by astronomers using existing or soon-to-be instruments.
Those possible ways are outlined by six different equations in their study that connect a singularity's spin to the separations, angular alignments and brightness of the two split images.
"If you ask me whether I believe that naked singularities exist, I will tell you that I'm sitting on the fence," said Petters. "In a sense, I hope they are not there. I would prefer to have covered-up black holes. But I'm still open-minded enough to entertain the 'otherwise' possibility."
Note: This story has been adapted from a news release issued by Duke University.

Fausto Intilla

www.oloscience.com

A Warm South Pole? Yes, On Neptune!

Source:

http://www.sciencedaily.com/releases/2007/09/070918100600.htm

Science Daily — An international team of astronomers using ESO's Very Large Telescope has discovered that the south pole of Neptune is much hotter than the rest of the planet. This is consistent with the fact that it is late southern summer and this region has been in sunlight for about 40 years.

The scientists are publishing the first temperature maps of the lowest portion of Neptune's atmosphere, showing that this warm south pole is providing an avenue for methane to escape out of the deep atmosphere.
"The temperatures are so high that methane gas, which should be frozen out in the upper part of Neptune's atmosphere (the stratosphere), can leak out through this region," said Glenn Orton, lead author of the paper reporting the results. "This solves a long-standing problem of identifying the source of Neptune's high stratospheric methane abundances."
The temperature at the south pole is higher than anywhere else on the planet by about 10 degrees Celsius. The average temperature on Neptune is about minus 200 degrees Celsius.
Neptune, the farthest planet of our solar system, is located about 30 times farther away from the Sun than Earth is. Only about 1/900th as much sunlight reaches Neptune as our planet. Yet, the small amount of sunlight it receives significantly affects the planet's atmosphere.
The astronomers found that these temperature variations are consistent with seasonal changes. A Neptunian year lasts about 165 Earth years. It has been summer in the south pole of Neptune for about 40 years now, and they predict that as winter turns to summer in the north pole, an abundance of methane will leak out of a warm north pole in about 80 years.
"Neptune's south pole is currently tilted toward the Sun, just like the Earth's south pole is tilted toward the Sun during summer in the Southern Hemisphere," explains Orton. "But on Neptune the antarctic summer lasts 40 years instead of a few months, and a lot of solar energy input during that time can make big temperature differences between the regions in continual sunlight and those with day-night variations."
"Neptune has the strongest winds of any planet in the Solar System; sometimes, the wind blows there at more than 2000 kilometres per hour. It is certainly not the place you would like to go on a holiday," he adds.
The new observations also reveal mysterious high-latitude 'hot spots' in the stratosphere that have no immediate analogue in other planetary atmospheres. The astronomers think that these hot spots are generated by upwelling gas from much deeper in the atmosphere.
Methane is not the primary constituent of Neptune's atmosphere, which, as a giant planet, is mostly composed of the light gases, hydrogen and helium. But it is the methane in Neptune's upper atmosphere that absorbs the red light from the Sun and reflects the blue light back into space, making Neptune appear blue.
The new results were obtained with the mid-infrared camera/spectrometer VISIR on ESO's VLT 8.2-m Unit Telescope 3 (Melipal).
Reference: "Evidence for Methane Escape and Strong Seasonal and Dynamical Perturbations of Neptune's Atmospheric Temperatures", by Glenn S. Orton et al., is published by the research journal Astronomy and Astrophysics.
The team of astronomers includes Glenn S. Orton, Cédric Leyrat, and A. James Friedson (Jet Propulsion Laboratory, California Institute of Technology, USA), Thérèse Encrenaz (LESIA, Observatoire de Paris, France), and Richard Puetter (Center for Astrophysics & Space Sciences, University of California, USA).
Note: This story has been adapted from a news release issued by ESO.

Fausto Intilla

www.oloscience.com

Why Is The Hercules Dwarf Galaxy So Flat?

Source:

http://www.sciencedaily.com/releases/2007/09/070914113856.htm

Science Daily — Through some of the very first scientific observations with the brand-new Large Binocular Telescope (LBT) in Arizona, an international team of astronomers has found that a recently discovered tiny companion galaxy to our Milky Way, named the Hercules Dwarf Galaxy, has truly exceptional properties: while basically all of its known peers in the realm of these tiny dwarf galaxies are rather round, this galaxy at a distance of 430,000 Light Years appears highly flattened, either the shape of a disk or of a cigar.

The stars in many large galaxies are arranged in a disk-like configuration, as in our own Milky Way. Yet in smaller galaxies like the Hercules Dwarf, which despite its name has only a 10-millionth as many stars as the Milky Way, a disk-like configuration has never been observed before. Among the millions of well-studied galaxies none has ever been observed to have a cigar-like shape.
An explanation for the galaxy’s unusual shape is that it is being disrupted by the gravitational forces of the Milky Way. This effect is definitely seen in another of the Milky Way's satellites, the Sagittarius Dwarf. Yet, this object is 10 times closer to the Milky Way’s centre than the Hercules Dwarf Galaxy, and hence more highly affected by the destructive "tidal forces" of our Galaxy.
The Hercules Dwarf Galaxy can only have experienced a similar fate if its orbit would have brought it exceptionally close to the inner parts of the Milky Way. So, "The Hercules Dwarf Galaxy is either unlike any of the millions of galaxies studied so far, or circles our Galaxy on an extremely plunging orbit: an exceptional, unparalleled object at any rate", says Matthew Coleman of the Max Planck Institute for Astronomy in Germany, who headed this study.
The world’s single biggest telescope
These inferences were enabled by the very deep images provided by the brand-new Large Binocular Telescope (LBT), the largest single telescope in the world, which is located on the 3190-metre high Mount Graham in Arizona. Two giant mirrors with a diameter of 8.4 meters each, are hosted on the same mount acting as gigantic field glasses.
The pictures of the Hercules Dwarf Galaxy were created using the high-tech Large Binocular Camera (LBC-Blue), mounted at the Prime Focus of one of the two 8.4-metre mirrors. LBC-Blue and its future twin for the red spectral range, LBC-red, are being developed by Italian partners in the project. The camera and telescope work together like a giant digital camera which is able to capture images of ultra-faint objects with a field of view the size of the full moon. "I am delighted to see that the new camera is delivering such exciting images to the Astronomy community, off the bat," says Emanuele Giallongo of INAF/Rome, who built the camera. "We provided early ‘science demonstration time’ to our astronomers," says Richard Green, LBT Director, "so that they could show what can be done with this new facility. This result is just the first, with many more to come."
Study distant planets, stars and galaxies
By combining the optical paths of the two individual mirrors, the LBT will collect in its final increment as much light as a telescope whose mirrors have a diameter of 11.8 meters. This is a factor of 24 larger than the 2.4-metre mirror of the Hubble Space Telescope. Even more importantly, the LBT will then have the resolution of a 22.8-metre telescope, because it will use the most modern adaptive optics, superimposing pictures with an interferometric procedure.
The astronomers are thus able to compensate for the blurring caused by air turbulence. With that power, the LBT will open completely new possibilities in researching planets outside the solar system and the investigation of the faintest and most distant galaxies.
The LBC camera is the first of a suite of high-tech instruments with which the LBT will be equipped in the future. These additional instruments include spectrographs with different resolution and spectral sensitivity as well as very complex instruments which will combine the light path of the two giant main mirrors. Both the telescope and instruments are being built by an international collaboration among institutions in the United States, Italy and Germany.
The Partners in the LBT Corporation (LBTC) are: University of Arizona, USA; Istituto Nazionale di Astrofisica, Italy LBT Beteiligungsgesellschaft (LBTB), Germany (Max Planck Society, Astrophysical Institute Potsdam, University of Heidelberg); Ohio State University, USA The Research Corporation, USA (University of Notre Dame, University of Minnesota and University of Virginia)
Note: This story has been adapted from a news release issued by Max-Planck-Gesellschaft.

Fausto Intilla

www.oloscience.com

Early Star Formation In The Universe Illuminated

Source:

http://www.sciencedaily.com/releases/2007/09/070913140318.htm

Science Daily — A groundbreaking study has provided new insight into the way the first stars were formed at the start of the Universe, some 13 billion years ago.

Cosmologists from Durham University, publishing their results in the journal, Science, suggest that the formation of the first stars depends crucially on the nature of 'dark matter', the strange material that makes up most of the mass in the universe.
The discovery takes scientists a step further to determining the nature of dark matter, which remains a mystery since it was first discovered more than 70 years ago. It also suggests that some of the very first stars that ever formed can still be found in the Milky Way galaxy today.
Early structure formation in the Universe involves interaction between elusive particles known as 'dark matter'. Even though little is known about their nature, evidence for the presence of dark matter is overwhelming, from observations of galaxies, to clusters of galaxies, to the Universe as a whole.
After the Big Bang, the universe was mostly 'smooth', with just small ripples in the matter density. These ripples grew larger due to the gravitational forces acting on the dark matter particles contained in them. Eventually, gas was pulled into the forming structures, leading to the formation of the very first stars, about 100 million years after the Big Bang.
For their research, the team from Durham University's Institute for Computational Cosmology carried out sophisticated computer simulations of the formation of these early stars with accepted scientific models of so-called 'cold' as well as 'warm' dark matter.
The computer model found that for slow moving 'cold dark matter' particles, the first stars formed in isolation, with just a single, larger mass star forming per developing spherical dark matter concentration.
In contrast, for faster-moving 'warm dark matter', a large number of stars of differing sizes formed at the same time in a big burst of star formation. The bursts occurred in long and thin filaments.
One of the researchers, Dr Liang Gao, who receives funding from the UK's Science and Technologies Facilities Council, said: "These filaments would have been around 9000 light years long, which is about a quarter of the size of the Milky Way galaxy today. The very luminous star burst would have lit-up the dark universe in spectacular fashion."
Stars forming in the cold dark matter are massive. The larger a star is, the shorter its life span, so these larger mass stars would not have survived until today. However the warm dark matter model predicts the formation of low mass stars as well as larger ones and the scientists say the low mass stars would survive until today.
The research paves the way for observational studies which could bring scientists closer to finding out more about the nature of dark matter. Co-researcher, Dr Tom Theuns, said: "A key question that astronomers often ask is 'where are the descendants of the first stars today"' The answer is that, if the dark matter is warm, some of these primordial stars should be lurking around our galaxy."
The Durham University scientists also give new insights into the way that black holes could be formed. Most galaxies harbour in their centres monster black holes, some with masses more than a billion times the mass of the sun.
The team hypothesises that collisions between stars in the dense filament in the warm dark matter scenario lead to the formation of the seeds for such black holes.
Dr Theuns added: "Our results raise the exciting prospect of learning about the nature of dark matter from studying the oldest stars. Another tell-tale sign could be the gigantic black holes that live in centres of galaxies like the Milky Way. They could have formed during the collapse of the first filaments in a universe dominated by warm dark matter."
Note: This story has been adapted from a news release issued by Durham University.

Fausto Intilla

www.oloscience.com

Life On Mars 'Pregnancy Test' Successfully Launched

Source:

http://www.sciencedaily.com/releases/2007/09/070917112501.htm

Science Daily — Key components of a new approach to discover life on Mars were successfully launched into space Friday as part of a twelve-day, low-Earth orbit experiment to assess their survivability in the space radiation environment--a prelude future journeys to Mars.

The new approach is based on technology similar to that used in pregnancy test kits. The so-called immunoassays are embodied in the "Life Marker Chip" (LMC) experiment, which has the potential to detect trace levels of biomarkers in the Martian environment. Biomarkers are molecular fingerprints that indicate if life currently is, or ever was, present on Mars.
The LMC experiment has been proposed for the European Space Agency's ExoMars rover mission, which is planned for launch in 2013. The LMC experiment is in the development phase and is led by an international consortium with researchers including Andrew Steele, a staff member of Carnegie's Geophysical Laboratory in the United States, and scientists from the United Kingdom, The Netherlands, and Germany.
For the current mission, the consortium developed a tiny component, measuring only 1.5 inches x 1.6 inches x .5 inch ( 3.8 cm x 4.1 cm x 1.3 cm) and housing over 2000 samples, to test that the key molecular components to be used in the LMC technology can survive the rigors of space.
The experiment was launched from Baikonur Cosmodrome in Kazakhstan as part of the European Space Agency's BIOPAN-6 experiment platform. The LMC components will experience both weightlessness and the harsh space radiation environment while orbiting the Earth 180 times at an altitude of up to 190 miles (308 km) during the 11.8 day mission.
The BIOPAN-6 platform is mounted on the outside of an un-manned Russian FOTON spacecraft. Once in space the BIOPAN-6 platform will open to expose its contents directly to the space environment, testing both their resistance to space radiation and the space vacuum, before closing and returning to Earth on September 25th. The LMC components will then be taken back to laboratories in the United Kingdom and the United States to analyze the effect of the space flight.
The lead members of the consortium involved in the current mission are Deutsches Zentrum für Luft- und Raumfahrt (DLR) (Germany), Cranfield University (UK), Carnegie Institution of Washington (USA) and University of Leicester (UK).
Dr. Andrew Steele from the Carnegie Institution of Washington (USA) and one of the initial experiment proposers said, "in the USA we are currently flying related technology and components within the protected environment of the International Space Station (ISS) but this will be the first time that these types of materials will have flown unprotected in space in a manner similar to a flight to Mars."
Dr. Lutz Richter of DLR (Germany) and the principal investigator for the current experiment said, "This experiment is the culmination of a number of years of hard work and ground based tests to prove the viability of the LMC technology."
Dr. David Cullen, from Cranfield University (UK) and who leads the scientific input into the current experiment, said, "this will be our first space experiment to demonstrate our belief that immunoassay technology will have an important future role in space exploration and the search for life elsewhere in the Solar System."
Dr. Mark Sims from the University of Leicester (UK) and who heads the overall LMC project said, "this mission will be an important stepping stone in our ultimate goal of putting a LMC experiment on the surface of Mars and using it to search for evidence of Life."
A number of other people, organizations and companies have contributed to the experiment and these include Haptogen Ltd. (Aberdeen, UK), Oklahoma State University (USA), LioniX BV (Enschede, NL), Technische Universität München (Germany) and Dr Jan Toporski, formally of Christian-Albrechts-Universität zu Kiel (Germany).
*This release was adapted from a release by Cranfield Health, Cranfield University, Silsoe, Bedfordshire MK45 4DT, United Kingdom.
Note: This story has been adapted from a news release issued by Carnegie Institution.

Fausto Intilla

www.oloscience.com

'Missing Dwarf Galaxy' Problem May Be Solved

Source:

http://www.sciencedaily.com/releases/2007/09/070914173533.htm

Science Daily — Scientists may have solved a discrepancy between the number of extremely small, faint galaxies predicted to exist near the Milky Way and the number actually observed.

In an attempt to resolve the “Missing Dwarf Galaxy” problem, two astronomers used the W. M. Keck Observatory in Hawaii to study a population of the darkest, most lightweight galaxies known, each containing 99% dark matter. The findings suggest the “Missing Dwarf Galaxy” problem is not as severe as previously thought, and may have been solved completely.
“It seems that very small, ultra-faint galaxies are far more plentiful than we thought,” said Dr. Marla Geha, co-author of the study and a Plaskett Research Fellow at the Herzberg Institute of Astrophysics in Canada. “If you asked me last year whether galaxies this small and this dark existed, I would have said no. I’m astonished that so many tiny, dark matter-dominated galaxies have now been discovered.”
The Missing Dwarf Galaxy puzzle comes from a prediction of the “Cold Dark Matter” model, which explains the growth and evolution of the universe. It predicts large galaxies like the Milky Way should be surrounded by a swarm of up to several hundred smaller galaxies known as “dwarf galaxies.” However, until recently, only 11 such companions were known to be orbiting the Milky Way.
To explain this large discrepancy, theorists suggested that while hundreds of dwarf galaxies near the Milky Way may indeed exist, the majority might have few, if any, stars. If so, the galaxies would be comprised almost entirely of dark matter—a mysterious type of matter that has gravitational effects on ordinary atoms, but which does not produce any light. But proving the existence of a large number of nearly invisible galaxies seemed problematic, until now.
Dr. Josh Simon, a Millikan Postdoctoral Scholar at the California Institute of Technology, and Dr. Geha used the 10-meter Keck II telescope with the DEIMOS spectrograph to conduct follow-up studies of eight new dwarf galaxies first discovered with the Sloan Digital Sky Survey. The results enabled the duo to calculate precisely the total mass of each galaxy. To their surprise, each system was among the smallest ever measured, more than 10,000 times smaller than the Milky Way.
“The formation of such small galaxies is not very well understood from a theoretical perspective,” said Dr. Simon. “Explaining how stars form inside these remarkably tiny galaxies is difficult, and so it is hard to predict exactly how many dwarfs we should find near the Milky Way. Our work narrows the gap between the Cold Dark Matter theory and observations by significantly increasing the number of Milky Way dwarf galaxies and telling us more about the properties of these galaxies. We also now know that dwarf galaxies can be even smaller than we thought possible.”
Numerous, repeated measurements of 814 stars in the eight dwarf galaxies were obtained at W. M. Keck Observatory. The stars were found to be moving much slower than stars in any other known galaxy (about 4 to 7 km/sec.) For comparison, the Sun orbits the center of the Milky Way at a speed of about 220 km/sec. In all, the astronomers measured precise speeds for 18 to 214 stars in each galaxy, about three times more stars per galaxy than any previous study.
“This is a significant paper,” said Dr. Taft Armandroff, director of the W. M. Keck Observatory, whose own research includes the study of dwarf galaxies. “It is a compelling example of how large, ground-based telescopes can precisely measure the orbits of distant stars on the sky to just a few kilometers per second. I expect DEIMOS will soon tell us about the chemical composition of these stars to help us better understand how star formation takes place in such small galaxies.”
Some parameters of the Cold Dark Matter theory can now be updated to match observed conditions in the local universe. Based on the masses measured for the new dwarf galaxies, Drs. Simon and Geha concluded the fierce ultraviolet radiation given off by the first stars, which formed just a few hundred million years after the Big Bang, may have blown all of the hydrogen gas out of the dwarf galaxies forming at that time. The loss of gas prevented the galaxies from creating new stars, leaving them very faint, or in many cases completely dark. When this effect is included in theoretical models, the numbers of expected and observed dwarf galaxies agree.
“One of the implications of our results is that up to a few hundred completely dark galaxies really should exist in the Milky Way’s cosmic neighborhood,” said Dr. Geha. “If the Cold Dark Matter model is correct they have to be out there, and the next challenge for astronomers will be finding a way to detect their presence.”
Because the Sloan Digital Sky Survey only covered about 25 percent of the sky, future surveys of the remainder of the sky are expected to discover as many as 50 more dark matter dominated dwarf galaxies orbiting the Milky Way. Telescopes for one such survey, the Pan-STARRS project on Maui, are now under construction.
The paper, “Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem,” will be published in the November 10 issue of the Astrophysical Journal.
Funding for the project was provided by the California Institute of Technology under the Millikan Fellowship program and the Herzberg Institute of Astrophysics of the National Research Council of Canada. Data reduction software was made possible by the support of the National Science Foundation.
Observations were conducted at the W. M. Keck Observatory in Hawaii, a non-profit 501 (c) (3) organization. The governing board of Keck Observatory consists of directors from the California Institute of Technology and the University of California. In addition, the National Aeronautics and Space Administration and the W. M. Keck Foundation each have liaisons to the board.
Note: This story has been adapted from a news release issued by W. M. Keck Observatory.

Fausto Intilla

www.oloscience.com

Mars: Mysterious Ridges At The Mouth Of Tiu Valles

Source:

http://www.sciencedaily.com/releases/2007/09/070912111316.htm

Science Daily — Mars Express show the mouth of the Tiu Valles channel system on the red planet.

The mouth of Tiu Valles is an estuary-like landform. On Earth, an estuary is the tidal mouth of a river valley, or the end that meets the sea and fresh water comes into contact with seawater. In such an area, tidal effects are evident.
Tiu Valles is located at approximately 27° North and 330° East. The sun illuminates the scene from the North West, the lower left-hand side in the image.
Tiu Valles originates in the equatorial chaotic terrains at the mouth, at the eastern end of Valles Marineris. The morphology of this chaotic terrain is dominated by large-scale remnant massifs, which are large relief masses that have been moved and weathered as a block. These are randomly oriented and heavily eroded.
From there, the region extends to the north over a distance of 1500 km before terminating in Chryse Planitia. Along with Kasei Valles and Ares Valles, Tiu Valles is one of the major outflow channels entering the Chryse Planitia plain.
The scene in the images covers an area of approximately 140 by 80 km at the mouth of Tiu Valles. The region was made famous in 1997 when rover Sojourner of NASA’s Pathfinder mission landed about 600 km south-west of the mapped area.
Its winding, meandering ridges, bound by depressions, are eye-catching. The exact processes that formed these odd structures are unknown. One possibility is that during floods, water or water-rich surface layers came in contact with lava from the surrounding areas, which then might have led to the formation of these mysterious ridges.
The picture was taken in orbit 3103 on 10 June 2006 with a ground resolution of approximately 16 metres per pixel.
For related images see: http://www.esa.int/SPECIALS/Mars_Express/SEMWZZMPQ5F_0.html
Note: This story has been adapted from a news release issued by European Space Agency.

Fausto Intilla

www.oloscience.com

Missing Link In The Evolution Of Magnetic Cataclysmic Stars?

Source:

http://www.sciencedaily.com/releases/2007/09/070914105946.htm

Science Daily — An international team of astronomers might have discovered the missing link in the evolution of the so-called magnetic cataclysmic variable stars. They determined the spin and orbital periods of the binary star Paloma. They found that the Paloma system has a weird way of rotating that fills the gap between two classes of magnetic cataclysmic stars. Their results will soon be published in Astronomy & Astrophysics.

Cataclysmic variables (CVs) are a class of binary stars made up of a white dwarf [1] and a normal star much like our Sun. Both stars orbit so close to each other that the white dwarf accretes matter from the companion star. In most of the several hundred CVs known, the matter spirals around the white dwarf, forming a disk, before being accreted and incorporated into the star. About 20% of the known CVs include a white dwarf with a strong magnetic field of several million Gauss [2]. They are known as "magnetic CVs". The magnetic field of the white dwarf can be strong enough to disrupt the accretion disk or even to prevent the disc from forming.
Astronomers currently know two classes of magnetic CVs:
Polars (also known as the prototype star AM Herculis) have a strong enough magnetic field to synchronize the spin period of the stars and the orbital period of the system [3]. A departure from synchronization is observed for four AM Herculis stars, which are thought to be normal AM Herculis systems currently desynchronized by a recent nova explosion. The difference between the spin period and the orbital period, that is, the degree of asynchronism, is less than 2% for these near-synchronous polars.
Intermediate polars (known as DQ Herculis stars) have a lower magnetic field, and the spin period of the stars is shorter than the orbital period. The majority of the DQ Herculis stars have orbital periods longer than 3 hours and spin periods ranging from 33 seconds to 1 hour.
In a cataclysmic variable system, both stars are so close to each other (the whole system would match the size of our Sun) that astronomers cannot distinguish one star from the other. For studying CVs, they rely on indirect observations: measuring the variation in the brightness of the system, thereby estimating its characteristics (orbit size, period).
Dr. R. Schwarz and his colleagues [4] studied the candidate magnetic CV Paloma (also known as RX J0524+42), which has not yet been characterised. It does not fit either of the known CVs categories. The team presents both long- and short-term monitoring of this stellar system, using several European telescopes (1.2m OHP, 70 cm AIP, 1.23m Calar Alto), over a period ranging from 1995 to 2001. With this monitoring, they built the light curves and estimated the periods of the system. ROSAT observations of the system confirm that it has a strong magnetic field and thus belongs to the magnetic CVs.
From their observations, the team concludes that the faster white dwarf performs 14 spins around its own axis during 13 orbital revolutions. The weird degree of synchronization of the system presents the characteristics that makes Paloma so interesting. This bridges the gap between the two main classes of magnetic CVs: it spins much more slowly than any known intermediate polar, but is too much desynchronized to be an AM Herculis star. Paloma thus revives the old idea that both classes are evolutionarily linked together and that intermediate polars are the ancestors of the older AM Herculis stars. Theoreticians predict that Paloma is in the process of synchronization and should become a spin-locked AM Herculis star over the next 100 million years.
###
[1] A white dwarf is a dying star that has exhausted most of its nuclear fuel. It is extremely dense (1 ton per cm3), with about the mass of the Sun and the size of the Earth. Our Sun will become a white dwarf in about 4.5 billion years.
[2] For comparison, the Sun's magnetic field is about 50 Gauss and the magnetic field inside a nuclear medical imaging device is about 10000 Gauss.
[3] The Earth-Moon system illustrates the case for synchronization in astronomy: from the Earth, we always see the same side of the Moon because the spin period of the Moon is the same as its orbital period around the Earth.
[4] The team includes R. Schwarz, A.D. Schwope, A. Staude (Astrophysikalisches Institut Potsdam, Germany), A. Rau (CalTech, USA), G. Hasinger (MPI, Garching, Germany), T. Urrutia (UC Davis, USA), and C. Motch (Observatoire Astronomique, Strasbourg, France).
Note: This story has been adapted from a news release issued by Journal Astronomy & Astrophysics.

Fausto Intilla

www.oloscience.com

Japan's KAGUYA Spacecraft Blasts Off To Explore The Moon

Source:

http://www.sciencedaily.com/releases/2007/09/070914123848.htm

Science Daily — Japan has successfully launched a new unmanned spacecraft to explore the Moon -- the largest lunar mission since the Apollo program.

Mitsubishi Heavy Industries, Ltd. and the Japan Aerospace Exploration Agency (JAXA) announced the launch of the Lunar Orbit Explorer "KAGUYA" (SELENE) by the H-IIA Launch Vehicle No. 13 (H-IIA F13) at 10:31:01 a.m. on September 14, 2007 (Japan Standard Time, JST) from the Tanegashima Space Center. The launch vehicle flew smoothly, and, at about 45 minutes and 34 seconds after liftoff, the separation of the KAGUYA was confirmed.
The mission of the SELenological and ENgineering Explorer "KAGUYA" (SELENE), Japan’s first large lunar explorer, is being keenly anticipated by many countries.
The major objectives of the mission are to understand the Moon’s origin and evolution, and to observe the moon in various ways in order to utilize it in the future. The lunar missions that have been conducted so far have gathered a large amount of information on the Moon, but the mysteries of its origin and evolution have been left unsolved.
KAGUYA will investigate the entire moon in order to obtain information on its elemental and mineralogical composition, its geography, its surface and sub-surface structure, the remnant of its magnetic field, and its gravity field. The results are expected to lead to a better overall understanding of the Moon’s evolution.
At the same time, the observation equipment installed on the orbiting satellite will observe plasma, the electromagnetic field and high-energy particles. The data obtained in this way will be of great scientific importance for exploring the possibility of using the moon for human endeavors.
KAGUYA’s configuration and mission
KAGUYA consists of the Main Orbiter and two small satellites (Relay Satellite and VRAD Satellite). The Main Orbiter will reach the vicinity of the Moon. Once it has reached the Moon, it will be placed into a peripolar orbit at an altitude of 100 km. The Relay Satellite will be placed in an elliptic orbit at an apogee of 2400 km, and will relay communications between the Main Orbiter and the ground station. The VRAD Satellite will play a significant role in measuring the gravitational field around the Moon. The Main Orbiter will be employed for about one year and will observe the entire Moon.
Note: This story has been adapted from a news release issued by Japan Aerospace Exploration Agency.

Fausto Intilla

www.oloscience.com

Exoplanet Offers Clues To Earth's Future

Source:

http://www.sciencedaily.com/releases/2007/09/070912130828.htm

Science Daily — An international team of astronomers that includes Steve Kawaler of Iowa State University has announced the first discovery of a planet orbiting a star near the end of its life.

The news provides a preliminary picture of what could be the Earth's destiny in four to five billion years. That's when the sun will exhaust its hydrogen fuel, expand enormously as a red giant and expel its outer layers in an explosive helium flash.
The planet discovered by the researchers, "V 391 Pegasi b," has survived all those changes to its sun.
The international research team was led by Roberto Silvotti from the INAF-Osservatorio Astronomico di Capodimonte in Naples, Italy. They discovered the planet orbiting "V 391 Pegasi," a faint star in the constellation of Pegasus.
"The exciting thing about finding a planet around this star is that it indicates that planetary systems can survive the giant phase and the helium flash of their parent star," said Kawaler, an Iowa State professor of physics and astronomy. "It bodes well for the survival of our own Earth in the distant future. Before V 391 Pegasi lost its outer regions at the helium flash, the planet orbited the star at about the same distance that the Earth orbits our sun."
But, Kawaler said, "We shouldn't take too much heart in this -- this planet is larger than Jupiter, so a smaller planet like the Earth could still be vulnerable."
Kawaler helped the 23-member research team make its discovery by coordinating observations during a 2003 run of the Whole Earth Telescope. Iowa State is a lead institution in the Whole Earth Telescope, a worldwide network of cooperating observatories that allow astronomers to take uninterrupted measurements of variable stars that change in brightness. The discovery of V 391 Pegasi b was made by detailed measurements of the clocklike variation of the star caused by the planet tugging on it.
Kawaler also advanced the project by doing theoretical calculations to make sure irregularities of the star's orbital motion were caused by the orbiting planet.
The astronomers found that at the present time, V 391 Pegasi b has an orbital distance 1.7 times the medium distance between the Earth and the sun. As stars age and reach their red giant phase, they undergo an enormous expansion (with their volume increasing by a factor of millions) that can easily reach and engulf their inner planets.
"The same will happen to the sun," Silvotti said. "As far as our planets are concerned, we expect Mercury and Venus to disappear in the sun's envelope, whereas Mars should survive. The fate of the Earth is less clear because its position is really at the limit: it appears more likely that the Earth will not survive the red giant expansion of the sun either, but it is not for sure."
As is the case for almost all planets beyond our solar system, V 391 Pegasi b cannot be seen directly. Silvotti said it took seven years of observations and calculations to confirm the existence of the planet.
The announcement, culminating seven years of research, will be published in the Sept. 13 issue of the journal Nature.
Note: This story has been adapted from a news release issued by Iowa State University.

Fausto Intilla

www.oloscience.com

Opportunity Takes A Dip Into Victoria Crater

Source:

http://www.sciencedaily.com/releases/2007/09/070911212029.htm

Science Daily — NASA's Mars Exploration Rover Opportunity entered Victoria Crater for the first time September 11, 2007. It radioed home information via a relay by NASA's Mars Odyssey orbiter, reporting its activities for the day.

Opportunity drove far enough in -- about four meters (13 feet) -- to get all six wheels past the crater rim. Then it backed uphill for about three meters (10 feet). The driving commands for the day included a precaution for the rover to stop driving if its wheels were slipping more than 40 percent. Slippage exceeded that amount on the last step of the drive, so Opportunity stopped with its front pair of wheels still inside the crater.
"We will do a full assessment of what we learned from the drive today and use that information to plan Opportunity's descent into the crater," said John Callas, rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Once Opportunity begins its extended exploration inside the crater, the rover will investigate layered rocks exposed on the interior slope.
NASA's Mars Exploration Rover Opportunity entered Victoria Crater during the rover's 1,291st Martian day, or sol, (Sept. 11, 2007). The rover team commanded Opportunity to drive just far enough into the crater to get all six wheels onto the inner slope, and then to back out again and assess how much the wheels slipped on the slope.
The driving commands for the day included a precaution for the rover to stop driving if the wheels were slipping more than 40 percent. Slippage exceeded that amount on the last step of the drive, so Opportunity stopped with its front pair of wheels still inside the crater. The rover team planned to assess results of the drive, then start Opportunity on an extended exploration inside the crater.
Note: This story has been adapted from a news release issued by NASA, Jet Propulsion Laboratory.

Fausto Intilla

www.oloscience.com

Cassini Flies By Saturn's Walnut-Shaped Moon Iapetus

Source:

http://www.sciencedaily.com/releases/2007/09/070911212807.htm

Science Daily — Cassini completed its closest flyby of the odd moon Iapetus on Sept. 10, 2007. The spacecraft flew about 1,640 kilometers (1,000 miles) from Iapetus' surface and is returning amazing views of the bizarre moon.

All the data were successfully recorded on the spacecraft. Twenty-one minutes into the first post-flyby data downlink, the spacecraft went into a precautionary condition called safe mode. The cause has been determined to be a solid state power switch that was tripped due to a galactic cosmic ray hit.
While in safe mode, the spacecraft turns off all unnecessary activities and transmits only essential engineering telemetry at a low data rate, while it awaits commands from Earth.
Tuesday morning, Sept. 11, commands were sent to the spacecraft to resume high rate science and engineering data playback. The project expects all data on the spacecraft will be returned to Earth during downlinks on Tuesday and Wednesday, with no impact on the Iapetus science data return beyond a brief delay.
Due to the safing event, the sequence executing on the spacecraft was halted, and Cassini's instruments will not be turned back on for three or four days. The last time Cassini was in safe mode was over four years ago.
Note: This story has been adapted from a news release issued by National Aeronautics And Space Administration.

Fausto Intilla

www.oloscience.com

NASA Astronomers Find Bizarre Planet-mass Object Orbiting Neutron Star

Source:

http://www.sciencedaily.com/releases/2007/09/070912154610.htm

Science Daily — Using NASA’s Swift and Rossi X-ray Timing Explorer (RXTE) satellites, astronomers have discovered one of the most bizarre planet-mass objects ever found.

The object’s minimum mass is only about 7 times the mass of Jupiter. But instead of orbiting a normal star, this low-mass body orbits a rapidly spinning pulsar. It orbits the pulsar every 54.7 minutes at an average distance of only about 230,000 miles (slightly less than the Earth-Moon distance).
"This object is merely the skeleton of a star," says co-discoverer Craig Markwardt of NASA’s Goddard Space Flight Center in Greenbelt, Md. "The pulsar has eaten away the star’s outer envelope, and all the remains is its helium-rich core."
Hans Krimm of NASA Goddard discovered the system on June 7, when Swift’s Burst Alert Telescope picked up an outburst of X rays and gamma rays in the direction of the galactic center. The source was named SWIFT J1756.9-2508 for its sky coordinates in the constellation Sagittarius.
RXTE began observing SWIFT J1756.9 on June 13 with its Proportional Counter Array (PCA). After analyzing the PCA data, Markwardt realized that the object was pulsing in X rays 182.07 times per second, which told him that it was a rapidly spinning pulsar. These so-called millisecond pulsars are neutron stars that spin hundreds of times per second, faster than a kitchen blender. Normally, the spin rate of neutron stars slows down as they age, but much like we can pull a string to “spin up” a top, gas spiraling onto a neutron star from its companion can maintain or even increase its fast spin.
In the case of SWIFT J1756.9-2508, Markwardt detected subtle modulations in the X-ray timing data that revealed a low-mass companion tugging the pulsar toward and away from Earth. His calculations show that the companion has a minimum mass about 7 times that of Jupiter. Because we don’t know the orbital inclination of the system, the companion’s actual mass is unknown, but it is extremely unlikely to exceed 30 Jupiters.
MIT astronomers led by Deepto Chakrabarty also observed the system with RXTE, before it faded to invisibility on June 21. Chakrabarty’s group reached identical conclusions, and the two teams have coauthored a paper that has been accepted for publication in the Astrophysical Journal Letters.
The system is only the eighth millisecond pulsar that is observed to be accreting mass from a companion. Only one other such system has a pulsar companion with such a low mass. The companion in this system, XTE J1807-294, also has a minimum mass of about 7 Jupiters. "Given that we don’t know the exact mass of either companion, ours could be the smallest," says Krimm.
The system probably formed several billion years ago, when it consisted of a very massive star and a smaller star with perhaps 1 to 3 solar masses. The more massive star evolved quickly and exploded as a supernova, leaving behind the neutron star. The smaller star eventually started to puff up en route to becoming a red giant, and the two objects became embedded in the extended stellar envelope. This drained orbital energy, causing the two stars to draw ever nearer, while simultaneously ejecting the envelope.
Today, the two objects are so close to each other than the neutron star’s powerful gravity produces a tidal bulge on its companion, siphoning off gas that flows into a disk that surrounds the neutron star. The flow eventually becomes unstable and dumps large quantities of gas onto the neutron star, causing an outburst like the one observed in June.
Evolution models by Christopher Deloye of Northwestern University suggest that the low-mass companion is helium dominated. "Despite its extremely low mass, the companion isn’t considered a planet because of its formation," says Deloye. "It’s essentially a white dwarf that has been whittled down to a planetary mass."
After billions of years, little remains of the companion star, and it remains unclear whether it will survive. "It’s been taking a beating, but that’s part of nature," adds Krimm.
With an estimated distance of roughly 25,000 light-years, the system is normally too faint to be detected at any wavelength, and is only visible during an outburst. SWIFT J1756.9 has never been seen to erupt until this June, so as Markwardt points out, "We don't know how long it will slumber before it wakes up again."
Note: This story has been adapted from a news release issued by NASA Goddard Space Flight Center.

Fausto Intilla

www.oloscience.com

Mars-Bound Phoenix Returns First Photo From Trip

Source:

http://www.sciencedaily.com/releases/2007/09/070911213517.htm

Science Daily — A camera flying aboard The University of Arizona-led Phoenix Mars Lander took its first picture during cruise and sent it back to Earth on Sept. 6. The lander's Robotic Arm Camera took the photo looking into the Robotic Arm's scoop. Both instruments are encased in a protection biobarrier, to ensure no Earth organisms are carried to Mars.

"It is a nice, clean picture with good sharp focus. One of these days it will be filled with Martian dirt," said Peter Smith, Phoenix principal investigator at the UA. "We have special pride in this, as it is a UA-German product."
The Robotic Arm Camera took an image of the Robotic Arm scoop using its red LED (Light-Emitting Diode) lamp. Human eyes see this image only in shades of gray, so the picture has been enhanced in false color to better represent what the camera sees.
Images from the Robotic Arm Camera, one of five imaging instruments on the lander, will be the only pictures taken and returned to Earth until Phoenix approaches and lands on Mars on May 25, 2008. Additional images will be taken by the Robotic Arm Camera later in the cruise stage.
The Robotic Arm Camera check was one of a series of instrument tests being completed as Phoenix cruises toward the red planet. Phoenix was about 57 million miles from Earth when the image was sent back. It is traveling at 76,000 miles per hour in relation to the sun.
On Mars, the Robotic Arm will dig trenches, scoop up soil and water-ice samples and deliver them to several instruments on the lander's deck for chemical and geological analysis.
The Robotic Arm Camera, built by the UA and Max Planck Institute, is attached to the Robotic Arm just above the scoop and will provide close-up, full-color images of the Martian surface, prospective soil and water-ice samples, samples collected in the scoop before delivery to the lander's science deck, and of the floor and side walls of the trenches. Phoenix's Robotic Arm was provided by the Jet Propulsion Laboratory, and the arm's scoop was manufactured by Honeybee Robotics of New York.
Phoenix launched from Cape Canaveral Air Force Station, Fla., on Aug. 4. It will fly to a site farther north than any previous Mars landing.
The solar-powered lander will robotically dig to underground ice and will run laboratory tests assessing whether the site could have ever been hospitable to microbial life. The instruments will also look for clues about the history of the water in the ice. They will monitor arctic weather as northern Mars' summer progresses toward fall, until solar energy fades and the mission ends. The Phoenix mission is led by Peter Smith of The University of Arizona, Tucson, with project management at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and development partnership at Lockheed Martin, Denver. International contributions are provided by the Canadian Space Agency; the University of Neuchatel, Switzerland; the Universities of Copenhagen and Aarhus, Denmark; the Max Planck Institute, Germany; and the Finnish Meteorological Institute.
Note: This story has been adapted from a news release issued by National Aeronautics And Space Administration.

Fausto Intilla

www.oloscience.com

What Is Dark Energy? 'Beyond Einstein' Program Aims To Investigate

Source:

http://www.sciencedaily.com/releases/2007/09/070906140741.htm

Science Daily — NASA and the U.S. Department of Energy should pursue the Joint Dark Energy Mission (JDEM) as the first mission in the "Beyond Einstein" program, according to a new report from the National Research Council.

Beyond Einstein is NASA's research roadmap for five proposed mission areas to study the most compelling questions at the intersection of physics and astronomy.
The committee that wrote the report added that another proposed mission to detect gravitational waves using the Laser Interferometer Space Antenna (LISA) should eventually become the flagship mission of Beyond Einstein, given that it is likely to provide an entirely new way to observe the universe. However, LISA needs more testing before a launch can be planned, whereas the Joint Dark Energy Mission is ready now for a competitive selection of mission concept proposals.
Prompted by Congress and the Office of Science and Technology Policy, NASA and DOE asked the committee to assess the five proposed mission areas and recommend one for first development and launch. NASA's Beyond Einstein program, set to begin in 2009, is comprised of two astronomical observatories, Constellation-X and LISA, as well as a series of probes: the Inflation Probe (IP), the Black Hole Finder Probe (BHFP), and JDEM.
"All of the mission areas in the Beyond Einstein program have the potential to fundamentally alter our understanding of the universe," said committee co-chair Charles F. Kennel, distinguished professor and director of the Environment and Sustainability Initiative at the University of California, San Diego. "But JDEM will provide direct insight into a key Beyond Einstein science question, and is the most technically feasible option for immediate development."
Of particular interest to researchers is whether the acceleration of the expansion of the universe varies over time. So far, three specific mission plans have been studied in this area: the Supernova Acceleration Probe (SNAP), the Dark Energy Space Telescope (DESTINY), and the Advanced Dark Energy Physics Telescope (ADEPT), but the eventual JDEM could be any one of the three or be based on a different option altogether.
The committee found that the underlying technology for a dark energy mission is, for the most part, in the prototype phase, and will require less development than most of the other missions. The potential gains for JDEM also outweigh its scientific risks, such as the possibility that the mission may not provide substantial insight beyond that provided by telescopes on the ground. The report recommends that NASA and DOE proceed immediately with a competition for mission proposals that will investigate the nature of dark energy with high precision.
The committee also recommended that NASA invest additional Beyond Einstein funds in technology development of the LISA program. LISA, which is funded through a partnership between NASA and the European Space Agency (ESA), is designed to detect gravitational waves arising from, among other phenomena, the merging of black holes.
The committee found that LISA will open up new ways of observing the universe, but must await results from ESA's "LISA Pathfinder" mission first. Scheduled for launch in 2009, LISA Pathfinder will test many of the new technologies required for the LISA program. Yet, some critical technologies, such as extended use of micro-Newton thruster technology, will not be tested. The report recommends that the development of these technologies should be a high priority for the Beyond Einstein program.
The report indicates that the three elements of Beyond Einstein that are not being recommended for immediate implementation are still important endeavors that should receive continued support. The committee found that because the Constellation-X mission is a general-purpose x-ray observatory capable of broad contributions to astrophysics, it should be funded and assessed in a broader context than the Beyond Einstein program.
The Black Hole Finder Probe and Inflation Probe missions will also make important scientific contributions; however, because of scope and technical readiness issues, they fell behind JDEM and LISA. The committee recommended that Constellation-X, Black Hole Finder Probe, and Inflation Probe receive continued support to prepare them for the next decadal survey of astronomy and astrophysics.
The study was sponsored by the U.S. Department of Energy and NASA. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.
Note: This story has been adapted from a news release issued by The National Academies.

Fausto Intilla

www.oloscience.com

Mars Rovers Survive Severe Dust Storms, Ready For Next Objectives

Source:

http://www.sciencedaily.com/releases/2007/09/070907165711.htm

Science Daily — Two months after sky-darkening dust from severe storms nearly killed NASA's Mars exploration rovers, the solar powered robots are awake and ready to continue their mission.
Opportunity's planned descent into the giant Victoria Crater was delayed, but now the rover is preparing to drive into the 800-meter-diameter crater (half-mile-diameter) as early as Sept. 11.
Spirit, Opportunity's rover twin, also survived the global dust storms. The rovers are 43 months into missions originally planned to last three months. On Sept. 5, Spirit climbed onto its long-term destination called Home Plate, a plateau of layered bedrock bearing clues to an explosive mixture of lava and water.
"These rovers are tough. They faced dusty winds, power starvation and other challenges -- and survived. Now they are back to doing groundbreaking field work on Mars. These spacecraft are amazing," said Alan Stern, associate administrator of NASA's Science Mission Directorate, Washington.
Victoria Crater contains an exposed layer of bright rocks that may preserve evidence of interaction between the Martian atmosphere and surface from millions of years ago, when the atmosphere might have been different from today's. Victoria is the biggest crater Opportunity has visited.
Martian dust storms in July blocked so much sunlight that researchers grew concerned the rovers' daily energy supplies could plunge too low for survival. Engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., put Opportunity onto a very low-energy regimen of no movement, few observations and reduced communication with Earth. Skies above both rovers remain dusty but have been clearing gradually since early August.
Dust from the sky has been falling onto both rovers' solar panels, impeding their ability to collect energy from the sun. However, beneficial wind gusts removed some of the new buildup from Opportunity almost as soon as it accumulated.
Opportunity drove to the lip of Victoria Crater in late August and examined possible entry routes. This week, Opportunity has been driving about 40 meters (about 130 feet) toward its planned entry point. The route will provide better access to a top priority target inside the crater: a bright band of rocks about 12 meters (about 40 feet) from the rim. "We chose a point that gives us a straight path down, instead of driving cross-slope from our current location," said Paolo Bellutta, a JPL rover driver plotting the route. "The rock surface on which Opportunity will be driving will provide good traction and control of its path into the crater."
For its first foray into the crater, Opportunity will drive just far enough to get all six wheels in; it will then back out and assess slippage on the inner slope. "Opportunity might be ready for that first 'toe dip' into the crater as early as next week," said JPL's John Callas, rover project manager. "In addition to the drives to get to the entry point, we still need to conduct checkouts of two of Opportunity's instruments before sending the rover into the crater."
The rover team plans to assess if dust has impaired use of the microscopic imager. If that tool is working, the team will use it to observe whether a scanning mirror for the miniature thermal emission spectrometer (Mini-TES) can function accurately. This mirror is high on the rover's camera mast. It reflects infrared light from the landscape to the spectrometer at the base of the mast, and it also can be positioned to close the hole in the mast as protection from dust. The last time the spectrometer was used, some aspects of the data suggested the instrument may have been viewing the inside of the mast instead of the Martian landscape.
"If the dust cover or mirror is no longer moving properly, we may have lost the ability to use that instrument on Opportunity," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the rovers' science instruments. "It would be the first permanent loss of an instrument on either rover. But we'll see."
The instrument already has provided extensive valuable information about rocks and soils in the Meridiani region where Opportunity works. "Mini-TES has told us a lot about the rocks and soils at Meridiani, but we've learned that the differences among Meridiani rocks are often too subtle for it to distinguish," Squyres said. "The same instrument on Spirit, at Gusev Crater, has a much more crucial role for us at this point in the mission because there is such diversity at Gusev." Researchers will rely heavily on a different type of instrument, Opportunity's alpha particle X-ray spectrometer, for analysis of rocks at the bright-band target layer in the crater.
The Jet Propulsion Laboratory manages the Mars Exploration Rover project for NASA's Science Mission Directorate. For images and information about the rovers, visit: http://www.nasa.gov/rovers.
Note: This story has been adapted from a news release issued by NASA/Jet Propulsion Laboratory.

Fausto Intilla
www.oloscience.com

Networks Create 'Instant World Telescope'

Source:

http://www.sciencedaily.com/releases/2007/09/070905103033.htm

Science Daily — For the first time, a CSIRO radio telescope has been linked to others in China and Europe in real-time, demonstrating the power of high-speed global networks and effectively creating a telescope almost as big as the Earth.

A CSIRO telescope near Coonabarabran NSW was recently used simultaneously with one near Shanghai, China, and five in Europe to observe a distant galaxy called 3C273.
“This is the first time we’ve been able to instantaneously connect telescopes half a world apart,” Dr Tasso Tzioumis, VLBI operations and development manager at CSIRO’s Australia Telescope National Facility said.
“It’s a fantastic technical achievement, and a tribute to the ability of the network providers to work together.”
Data from the telescopes was streamed around the world at a rate of 256 Mb per second - about ten times faster than the fastest broadband speeds available to Australian households - to a research centre in Europe, where it was processed with a special-purpose digital processor.
The results were then transmitted to Xi’an, China, where they were watched live by experts in advanced networking at the 24th APAN (Asia-Pacific Advanced Network) Meeting.
From Australia to Europe, the CSIRO data travelled on a dedicated 1 Gb per second link set up by the Australian, Canadian and Dutch national research and education networks, AARNet, CANARIE and SURFnet respectively.
“The diameter of the Earth is 12 750 km and the two most widely separated telescopes in our experiment were 12 304 km apart, in a straight line,”
Dr Tzioumis said.
Within Australia, the experiment used the 1 Gb per second networks that now connect CSIRO’s NSW observatories to Sydney and beyond. The links, installed in 2006, were funded by CSIRO and provided by AARNet (the Australian Academic Research Network).
The telescope-linking technique, VLBI (very long baseline interferometry) used to take weeks or months.
“We used to record data on tapes or disks at each telescope, along with time signals from atomic clocks. The tapes or disks would then be shipped to a central processing facility to be combined,” Dr Tzioumis said
“The more widely separated the telescopes, the more finely detailed the observations can be. The diameter of the Earth is 12 750 km and the two most widely separated telescopes in our experiment were 12 304 km apart, in a straight line,” Dr Tzioumis said.
The institutions that took part in the experiment are all collaborators in the EXPReS project (Express Production Real-time e-VLBI Service), which is coordinated by the Joint Institute for VLBI in Europe (JIVE) in The Netherlands.
Note: This story has been adapted from a news release issued by CSIRO Australia.

Fausto Intilla

www.oloscience.com

'Lego-block' Galaxies Discovered In Early Universe

Source:

http://www.sciencedaily.com/releases/2007/09/070906132814.htm

Science Daily — The conventional model for galaxy evolution predicts that small galaxies in the early Universe evolved into the massive galaxies of today by coalescing. Nine Lego-like "building block" galaxies initially detected by Hubble likely contributed to the construction of the Universe as we know it. "These are among the lowest mass galaxies ever directly observed in the early Universe" says Nor Pirzkal of the European Space Agency/STScI.

Pirzkal was surprised to find that the galaxies' estimated masses were so small. Hubble's cousin observatory, NASA's Spitzer Space Telescope was called upon to make precise determinations of their masses. The Spitzer observations confirmed that these galaxies are some of the smallest building blocks of the Universe.
These young galaxies offer important new insights into the Universe's formative years, just one billion years after the Big Bang. Hubble detected sapphire blue stars residing within the nine pristine galaxies. The youthful stars are just a few million years old and are in the process of turning Big Bang elements (hydrogen and helium) into heavier elements. The stars have probably not yet begun to pollute the surrounding space with elemental products forged within their cores.
"While blue light seen by Hubble shows the presence of young stars, it is the absence of infrared light in the sensitive Spitzer images that was conclusive in showing that these are truly young galaxies without an earlier generation of stars," says Sangeeta Malhotra of Arizona State University in Tempe, USA, one of the investigators.
The galaxies were first identified by James Rhoads of Arizona State University, USA, and Chun Xu of the Shanghai Institute of Technical Physics in Shanghai, China. Three of the galaxies appear to be slightly disrupted -- rather than being shaped like rounded blobs, they appear stretched into tadpole-like shapes. This is a sign that they may be interacting and merging with neighbouring galaxies to form larger, cohesive structures.
The galaxies were observed in the Hubble Ultra Deep Field (HUDF) with Hubble's Advanced Camera for Surveys and the Near Infrared Camera and Multi-Object Spectrometer as well as Spitzer's Infrared Array Camera and the European Southern Observatory's Infrared Spectrometer and Array Camera. Seeing and analysing such small galaxies at such a great distance is at the very limit of the capabilities of the most powerful telescopes.
Images taken through different colour filters with the ACS were supplemented with exposures taken through a so-called grism which spreads the different colours emitted by the galaxies into short "trails". The analysis of these trails allows the detection of emission from glowing hydrogen gas, giving both the distance and an estimate of the rate of star formation. These "grism spectra" - taken with Hubble and analysed with software developed at the Space Telescope-European Coordinating Facility in Munich, Germany - can be obtained for objects that are significantly fainter than can be studied spectroscopically with any other current telescope.
Note: This story has been adapted from a news release issued by ESA/Hubble Information Centre.

Fausto Intilla

www.oloscience.com