World's Most Sensitive Astronomical Camera Developed.

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ScienceDaily (Sep. 30, 2009) — A team of Université de Montréal researchers, led by physics PhD student Olivier Daigle, has developed the world's most sensitive astronomical camera. Marketed by Photon etc., a young Quebec firm, the camera will be used by the Mont-Mégantic Observatory and NASA, which purchased the first unit.

The camera is made up of a CCD controller for counting photons; a digital imagery device that amplifies photons observed by astronomical cameras or by other instruments used in situations of very low luminosity. The controller produces 25 gigabytes of data per second.
Electric signals used to pilot the imagery chip are 500 times more precise than those of a conventional controller. This increased precision helps reduce noise that interferes with the weak signals coming from astronomical objects in the night sky. The controller allows to substantially increase the sensitivity of detectors, which can be compared to the mirror of the Mont-Mégantic telescope doubling its diameter.
"The first astronomical results are astounding and highlight the increased sensitivity acquired by the new controller," says Daigle. "The clarity of the images brings us so much closer to the stars that we are attempting to understand."
A thriving Quebec company Photon etc. developed a commercial version of the controller devised by Daigle and his team and integrated it in complete cameras. NASA was first to place an order for one of these cameras and was soon followed by a research group from the University of Sao Paulo, and by a European-Canadian consortium equipping a telescope in Chili. In addition, researchers in nuclear medicine, bioluminescence, Raman imaging and other fields requiring rapid imagery have expressed interest in purchasing the cameras.
Photon etc. is a Quebec research and development company that specializes in the manufacting of photonic measurement and analysis instruments. The company is growing rapidly after spending four years in the Université de Montréal and its affiliated École Polytechnique IT business incubator.
"The sensitivity of the cameras developed by the Centre de recherche en astrophysique du Québec (CRAQ) and Photon etc. will not only help us better understand the depths of the universe but also better perceive weak optical signals coming from the human body. These signals can reveal the early signs of several diseases such as macular degeneration and certain types of cancer. An early diagnostic leads to early intervention, hopefully before the disease becomes more serious thus saving lives and important costs," says Sébastien Blais-Ouellette, president of Photon etc.
Scientific results for the camera were recently featured in the Publications of the Astronomical Society of the Pacific, a prestigious instrumentation journal.
This research was made possible thanks to the financial support of the Natural Sciences And Engineering Research Council of Canada, Photon etc., the Canada Foundation for Innovation, the Fonds québécois de la recherche sur la nature et les technologies.
Adapted from materials provided by University of Montreal.

James Webb Space Telescope Begins To Take Shape At Goddard.

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ScienceDaily (Sep. 30, 2009) — NASA's James Webb Space Telescope is starting to come together. A major component of the telescope, the Integrated Science Instrument Module structure, recently arrived at NASA Goddard Space Flight Center in Greenbelt, Md. for testing in the Spacecraft Systems Development and Integration Facility.

The Integrated Science Instrument Module, or ISIM, is an important component of the Webb telescope. The ISIM includes the structure, four scientific instruments or cameras, electronics, harnesses, and other components.
The ISIM structure is the "backbone" of the ISIM. It is similar to the chassis of a car. Just as a car chassis provides support for the engine and holds other components, the ISIM Structure supports and holds the four Webb telescope science instruments : the Mid-Infrared Instrument (MIRI), the Near-Infrared Camera (NIRCam), the Near-Infrared Spectrograph (NIRSpec) and the Fine Guidance Sensor (FGS). Each of these instruments were created and assembled by different program partners around the world.
When fully assembled, the ISIM will be the size of a small room with the structure acting as a skeleton supporting all of the instruments. Ray Lundquist, ISIM Systems Engineer, at NASA Goddard, commented that "The ISIM structure is truly a one-of-a-kind item. There is no second ISIM being made."
Before arriving at Goddard, the main ISIM structure – a state of the art, cryogenic-compatible, optical structure was designed by a team of engineers at Goddard, and assembled by Alliant Techsystems (ATK) at its Magna, Utah facility. That's the same facility where the Webb Telescope's Backplane is also being assembled.
Now that the structure has arrived at Goddard, it will undergo rigorous qualification testing to demonstrate its ability to survive the launch and extreme cold of space, and to precisely hold the science instruments in the correct position with respect to the telescope. Once the ISIM structure passes its qualification testing, the process of integrating into it all of the other ISIM Subsystems, including the Science Instruments, will begin.
Each of the four instruments that will be housed in the ISIM is critical to the Webb telescope's mission. The MIRI instrument will provide information on the formation and evolution of galaxies, the physical processes of star and planet formation, and the sources of life-supporting elements in other solar systems. The NIRCam will detect the first galaxies to form in the early universe, map the morphology and colors of galaxies; detect distant supernovae; map dark matter and study stellar populations in nearby galaxies. NIRSpec's microshutter cells can be opened or closed to view or block a portion of the sky which allows the instrument to do spectroscopy on many objects simultaneously, measuring the distances to galaxies and determining their chemical content. The FGS is a broadband guide camera used for both "guide star" acquisition and fine pointing. The FGS also includes the scientific capability of taking images at individual wavelengths of infrared light to study chemical elements in stars and galaxies.
In addition to designing the ISIM structure, NASA Goddard provides other infrastructure subsystems critical for the operation of the instruments, including the ISIM Thermal Control Subsystem; ISIM Control and Data Handling Subsystem; ISIM Remote Services Unit; ISIM Flight Software; ISIM Electronics Compartment, and ISIM Harness Assemblies.
The ISIM itself is very complicated and is broken into three distinct areas:
The first area involves the cryogenic instrument module. This is a critical area, because it keeps the instrument cool. Otherwise, the Webb telescope's heat would interfere with the science instruments’ infrared cameras. So, the module keeps components as cold as -389 degrees Fahrenheit (39 Kelvin). The MIRI instrument is further cooled by a cryocooler refrigerator to -447 degrees Fahrenheit (7 Kelvin).
The second area is the ISIM Electronics Compartment, which provides the mounting surfaces and a thermally-controlled environment for the instrument control electronics.
The third area is the ISIM Command and Data Handling subsystem, which includes ISIM flight Software, and the MIRI cryocooler compressor and control electronics.
NASA Goddard will be assembling and testing the ISIM and its components over the next several years. The integrated ISIM will then be mounted onto the main Webb telescope.
The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth. It is expected to launch in 2014. The telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.
Related Links:
For more information about each of the instruments on the ISIM, visit:
http://www.jwst.nasa.gov/instruments.html
For more information about the Webb Telescope, visit:
http://www.jwst.nasa.gov/
Adapted from materials provided by NASA/Goddard Space Flight Center.

'Ram Pressure' Stripping Galaxies, Hubble Space Telescope Scientists Find

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ScienceDaily (Sep. 30, 2009) — A newly released set of images, taken by the NASA/ESA Hubble Space Telescope before the recent Servicing Mission, highlight the ongoing drama in two galaxies in the Virgo Cluster affected by a process known as "ram pressure stripping", which can result in peculiar-looking galaxies.

An extremely hot X-ray emitting gas known as the intra-cluster medium lurks between galaxies within clusters. As galaxies move through this intra-cluster medium, strong winds rip through galaxies distorting their shape and even halting star formation.
Ram pressure is the drag force that results when something moves through a fluid — much like the wind you feel in your face when bicycling, even on a still day — and occurs in this context as galaxies orbiting about the centre of the cluster move through the intra-cluster medium, which then sweeps out gas from within the galaxies.
The spiral galaxy NGC 4522 is located some 60 million light-years away from Earth and it is a spectacular example of a spiral galaxy currently being stripped of its gas content. The galaxy is part of the Virgo galaxy cluster and its rapid motion within the cluster results in strong winds across the galaxy as the gas within is left behind. Scientists estimate that the galaxy is moving at more than 10 million kilometres per hour. A number of newly formed star clusters that developed in the stripped gas can be seen in the Hubble image.
Even though this is a still image, Hubble's view of NGC 4522 practically swirls off the page with apparent movement. It highlights the dramatic state of the galaxy, with an especially vivid view of the ghostly gas being forced out of it. Bright blue pockets of new star formation can be seen to the right and left of centre. The image is sufficiently deep to show distant background galaxies.
The image of NGC 4402 also highlights some telltale signs of ram pressure stripping such as the curved, or convex, appearance of the disc of gas and dust, a result of the forces exerted by the heated gas. Light being emitted by the disc backlights the swirling dust that is being swept out by the gas. Studying ram pressure stripping helps astronomers better understand the mechanisms that drive the evolution of galaxies, and how the rate of star formation is suppressed in very dense regions of the Universe like clusters.
Both images were taken by the Advanced Camera for Surveys on Hubble before it suffered from a power failure in 2007. Astronauts on Servicing Mission 4 in May 2009 were able to restore ACS during their 13-day mission.
Adapted from materials provided by ESA/Hubble Information Centre.

Raining Pebbles: Rocky Exoplanet Has Bizarre Atmosphere, Simulation Suggests.

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ScienceDaily (Oct. 1, 2009) — So accustomed are we to the sunshine, rain, fog and snow of our home planet that we find it next to impossible to imagine a different atmosphere and other forms of precipitation.

To be sure, Dr. Seuss came up with a green gluey substance called oobleck that fell from the skies and gummed up the Kingdom of Didd, but it had to be conjured up by wizards and was clearly a thing of magic.
Not so the atmosphere of COROT-7b, an exoplanet discovered last February by the COROT space telescope launched by the French and European space agencies.
According to models by scientists at Washington University in St. Louis, COROT-7b's atmosphere is made up of the ingredients of rocks and when "a front moves in," pebbles condense out of the air and rain into lakes of molten lava below.
The work, by Laura Schaefer, research assistant in the Planetary Chemistry Laboratory, and Bruce Fegley Jr., Ph.D., professor of earth and planetary sciences in Arts & Sciences, appears in the Oct. 1 issue of The Astrophysical Journal.
Astronomers have found nearly 400 extra-solar planets, or exoplanets, in the past 20 years. But because of the limitations of the indirect means by which they are discovered, most are Hot Jupiters, chubby gas giants orbiting close to their parent stars. (More than 1,300 Earths could be packed inside Jupiter, which has 300 times the mass of Earth.)
COROT-7b, on the other hand, is less than twice the size of Earth and only five times its mass.
It was the first planet found orbiting the star COROT-7, an orange dwarf in the constellation Monoceros, or the Unicorn. (This priority is designated by the letter b.)
Solid as a Rock
In August 2009 a consortium of European observatories led by the Swiss reported the discovery of COROT-7c, a second planet orbiting COROT-7.
Using the data from both planets, they were able to calculate that COROT-7b has an average density about the same as Earth's. This means it is almost certainly a rocky planet made up of silicate rocks like those in Earth's crust, says Fegley.
Not that anyone would call it Earth-like, much less hospitable to life. The planet and its star are separated by only 1.6 million miles, 23 times less than the distance between the parboiled planet Mercury and our Sun.
Because the planet is so close to the star, it is gravitationally locked to it in the same way the Moon is locked to Earth. One side of the planet always faces its star, just as one side of the Moon always faces Earth.
This star-facing side has a temperature of about 2600 degrees Kelvin (4220 degrees Fahrenheit). That's infernally hot—hot enough to vaporize rocks. The global average temperature of Earth's surface, in contrast, is only about 288 degrees Kelvin (59 degrees Fahrenheit).
The side in perpetual shadow, on the other hand, is positively chilly at 50 degrees Kelvin (-369 degrees Fahrenheit).
Perhaps because they were cooked off, COROT-7b's atmosphere has none of the volatile elements or compounds that make up Earth's atmosphere, such as water, nitrogen and carbon dioxide.
"The only atmosphere this object has is produced from vapor arising from hot molten silicates in a lava lake or lava ocean," Fegley says.
What might that atmosphere be like? To find out Schaefer and Fegley have used thermochemical equilibrium calculations to model COROT-7b's atmosphere.
The calculations, which reveal which mineral assemblages are stable under different conditions, were carried out with MAGMA, a computer program Fegley developed in 1986 with the late A. G. W. Cameron, a professor of astrophysics at Harvard University.
Schaefer and Fegley modified the MAGMA program in 2004 in order to study high-temperature volcanism on Io, Jupiter's innermost Galilean satellite. This modified version was used in their present work.
Raining Rocks
Because the scientists didn't know the exact composition of the planet, they ran the program with four different starting compositions. "We got essentially the same result in all four cases," says Fegley.
"Sodium, potassium, silicon monoxide and then oxygen — either atomic or molecular oxygen — make up most of the atmosphere." But there are also smaller amounts of the other elements found in silicate rock, such as magnesium, aluminum, calcium and iron.
Why is there oxygen on a dead planet, when it didn't show up in Earth's atmosphere until 2.4 billion years ago, when plants started to produce it?
"Oxygen is the most abundant element in rock," says Fegley, "so when you vaporize rock what you end up doing is producing a lot of oxygen."
The peculiar atmosphere has its own singular weather. "As you go higher the atmosphere gets cooler and eventually you get saturated with different types of 'rock' the way you get saturated with water in the atmosphere of Earth," explains Fegley. "But instead of a water cloud forming and then raining water droplets, you get a 'rock cloud' forming and it starts raining out little pebbles of different types of rock."
Even more strangely, the kind of rock condensing out of the cloud depends on the altitude. The atmosphere works the same way as fractionating columns, the tall knobby columns that make petrochemical plants recognizable from afar. In a fractionating column, crude oil is boiled and its components condense out on a series of trays, with the heaviest one (with the highest boiling point) sulking at the bottom, and the lightest (and most volatile) rising to the top.
Instead of condensing out hydrocarbons such as asphalt, petroleum jelly, kerosene and gasoline, the exoplanet's atmosphere condenses out minerals such as enstatite, corundum, spinel, and wollastonite. In both cases the fractions fall out in order of boiling point.
Elemental sodium and potassium, which have very low boiling points in comparison with rocks, do not rain out but would instead stay in the atmosphere, where they would form high gas clouds buffeted by the stellar wind from COROT-7.
These large clouds may be detectable by Earth-based telescopes. The sodium, for example, should glow in the orange part of the spectrum, like a giant but very faint sodium vapor streetlamp.
Observers have recently spotted sodium in the atmospheres of two other exoplanets.
The atmosphere of COROT-7b may not be breathable, but it is certainly amusing.
Adapted from materials provided by Washington University in St. Louis.

Planck Snaps Its First Images Of Ancient Cosmic Light.

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ScienceDaily (Sep. 20, 2009) — Preliminary results from ESA’s Planck mission to study the early Universe indicate that the data quality is excellent. This bodes well for the full sky survey that has just begun.

Planck started surveying the sky regularly from its vantage point at the second Lagrange point of the Sun-Earth system, L2, on 13 August. The instruments were fine-tuned for optimum performance in the period preceding this date.
ESA's Planck microwave observatory is the first European mission designed to study the Cosmic Microwave Background – the relic radiation from the Big Bang.
Following launch on 14 May, checkouts of the satellite's subsystems were started in parallel with the cool-down of its instruments' detectors. The detectors are looking for variations in the temperature of the Cosmic Microwave Background that are about a million times smaller than one degree – this is comparable to measuring from Earth the body heat of a rabbit sitting on the Moon. To achieve this, Planck's detectors must be cooled to extremely low temperatures, some of them being very close to absolute zero (–273.15°C, or zero Kelvin, 0K).
With check-outs of the subsystems finished, instrument commissioning, optimisation, and initial calibration was completed by the second week of August.
The 'first light' survey, which began on 13 August, was a two-week period during which Planck surveyed the sky continuously. It was carried out to verify the stability of the instruments and the ability to calibrate them over long periods to the exquisite accuracy needed.
This survey was completed on 27 August, yielding maps of a strip of the sky, one for each of Planck's nine frequencies. Each map is a ring, about 15° wide, stretching across the full sky. Preliminary analysis indicates that the quality of the data is excellent.
Routine operations started as soon as the first light survey was completed, and surveying will now continue for at least 15 months without a break. In approximately 6 months, the first all-sky map will be assembled.
Within its allotted operational life of 15 months, Planck will gather data for two complete sky maps. To fully exploit the high sensitivity of Planck, the data will require delicate adjustments and careful analysis. It promises to return a treasure trove that will keep both cosmologists and astrophysicists busy for decades to come.
Adapted from materials provided by European Space Agency.

Rare Meteorite Found Using New Camera Network In Australian Desert.

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ScienceDaily (Sep. 20, 2009) — Researchers have discovered an unusual kind of meteorite in the Western Australian desert and have uncovered where in the Solar System it came from, in a very rare finding published in the journal Science.

Meteorites are the only surviving physical record of the formation of our Solar System and by analysing them researchers can glean valuable information about the conditions that existed when the early Solar System was being formed. However, information about where individual meteorites originated, and how they were moving around the Solar System prior to falling to Earth, is available for only a dozen of around 1100 documented meteorite falls over the past two hundred years.
Dr Phil Bland, the lead author of today's study from the Department of Earth Science and Engineering at Imperial College London, said: "We are incredibly excited about our new finding. Meteorites are the most analysed rocks on Earth but it's really rare for us to be able to tell where they came from. Trying to interpret what happened in the early Solar System without knowing where meteorites are from is like trying to interpret the geology of Britain from random rocks dumped in your back yard."
The new meteorite, which is about the size of cricket ball, is the first to be retrieved since researchers from Imperial College London, Ondrejov Observatory in the Czech Republic, and the Western Australian Museum, set up a trial network of cameras in the Nullarbor Desert in Western Australia in 2006.
The researchers aim to use these cameras to find new meteorites, and work out where in the Solar System they came from, by tracking the fireballs that they form in the sky. The new meteorite was found on the first day of searching using the new network, by the first search expedition, within 100m of the predicted site of the fall. This is the first time a meteorite fall has been predicted using only the data from dedicated instruments.
The meteorite appears to have been following an unusual orbit, or path around the Sun, prior to falling to Earth in July 2007, according to the researchers' calculations. The team believes that it started out as part of an asteroid in the innermost main asteroid belt between Mars and Jupiter. It then gradually evolved into an orbit around the Sun that was very similar to Earth's. The other meteorites that researchers have data for follow orbits that take them back, deep into the main asteroid belt.
The new meteorite is also unusual because it is composed of a rare type of basaltic igneous rock. The researchers say that its composition, together with the data about where the meteorite comes from, fits with a recent theory about how the building blocks for the terrestrial planets were formed. This theory suggests that the igneous parent asteroids for meteorites like today's formed deep in the inner Solar System, before being scattered out into the main asteroid belt. Asteroids are widely believed to be the building blocks for planets like the Earth so today's finding provides another clue about the origins of the Solar System.
The researchers are hopeful that their new desert network could yield many more findings, following the success of their first meteorite search.
Dr Bland added: "We're not the first team to set up a network of cameras to track fireballs, but other teams have encountered problems because meteorites are small rocks and they're hard to find in vegetated areas. Our solution was quite simple - build a fireball network in a place where it's easy to find them. The Nullarbour Desert is ideal because there's very little vegetation and dark rocks show up really easily on the light desert plain.
"It was amazing to find a meteorite that we could track back to its origin in the asteroid belt on our first expedition using our small trial network. We're cautiously optimistic that this find could be the first of many and if that happens, each find may give us more clues about how the Solar System began," said Dr Bland.
The researchers' network of cameras takes a single time-lapse picture every night to record any fireballs in the sky. When a meteorite falls, researchers can then use complex calculations to uncover what orbit the meteorite was following and where the meteorite is likely to have landed, so that they can retrieve it.
Adapted from materials provided by Imperial College London.

"The solar wind can hit Earth like a fire hose even when there are virtually no sunspots."

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ScienceDaily (Sep. 18, 2009) — Challenging conventional wisdom, new research finds that the number of sunspots provides an incomplete measure of changes in the Sun's impact on Earth over the course of the 11-year solar cycle. The study, led by scientists at the High Altitude Observatory of the National Center for Atmospheric Research (NCAR) and the University of Michigan, finds that Earth was bombarded last year with high levels of solar energy at a time when the Sun was in an unusually quiet phase and sunspots had virtually disappeared.

"The Sun continues to surprise us," says NCAR scientist Sarah Gibson, the lead author. "The solar wind can hit Earth like a fire hose even when there are virtually no sunspots."
The study, also written by scientists at NOAA and NASA, is being published today in the Journal of Geophysical Research - Space Physics. It was funded by NASA and by the National Science Foundation, NCAR's sponsor.
Scientists for centuries have used sunspots, which are areas of concentrated magnetic fields that appear as dark patches on the solar surface, to determine the approximately 11-year solar cycle. At solar maximum, the number of sunspots peaks. During this time, intense solar flares occur daily and geomagnetic storms frequently buffet Earth, knocking out satellites and disrupting communications networks.
Gibson and her colleagues focused instead on another process by which the Sun discharges energy. The team analyzed high-speed streams within the solar wind that carry turbulent magnetic fields out into the solar system.
When those streams blow by Earth, they intensify the energy of the planet's outer radiation belt. This can create serious hazards for weather, navigation, and communications satellites that travel at high altitudes within the outer radiation belts, while also threatening astronauts in the International Space Station. Auroral storms light up the night sky repeatedly at high latitudes as the streams move past, driving mega-ampere electrical currents about 75 miles above Earth's surface. All that energy heats and expands the upper atmosphere. This expansion pushes denser air higher, slowing down satellites and causing them to drop to lower altitudes.
Scientists previously thought that the streams largely disappeared as the solar cycle approached minimum. But when the study team compared measurements within the current solar minimum interval, taken in 2008, with measurements of the last solar minimum in 1996, they found that Earth in 2008 was continuing to resonate with the effects of the streams. Although the current solar minimum has fewer sunspots than any minimum in 75 years, the Sun's effect on Earth's outer radiation belt, as measured by electron fluxes, was more than three times greater last year than in 1996.
Gibson said that observations this year show that the winds have finally slowed, almost two years after sunspots reached the levels of last cycle's minimum.
The authors note that more research is needed to understand the impacts of these high-speed streams on the planet. The study raises questions about how the streams might have affected Earth in the past when the Sun went through extended periods of low sunspot activity, such as a period known as the Maunder minimum that lasted from about 1645 to 1715.
"The fact that Earth can continue to ring with solar energy has implications for satellites and sensitive technological systems," Gibson says. "This will keep scientists busy bringing all the pieces together."
Buffeting Earth with streams of energy
For the new study, the scientists analyzed information gathered from an array of space- and ground-based instruments during two international scientific projects: the Whole Sun Month in the late summer of 1996 and the Whole Heliosphere Interval in the early spring of 2008. The solar cycle was at a minimal stage during both the study periods, with few sunspots in 1996 and even fewer in 2008.
The team found that strong, long, and recurring high-speed streams of charged particles buffeted Earth in 2008. In contrast, Earth encountered weaker and more sporadic streams in 1996. As a result, the planet was more affected by the Sun in 2008 than in 1996, as measured by such variables as the strength of electron fluxes in the outer radiation belt, the velocity of the solar wind in the vicinity of Earth, and the periodic behavior of auroras (the Northern and Southern Lights) as they responded to repeated high-speed streams.
The prevalence of high-speed streams during this solar minimum appears to be related to the current structure of the Sun. As sunspots became less common over the last few years, large coronal holes lingered in the surface of the Sun near its equator. The high-speed streams that blow out of those holes engulfed Earth during 55 percent of the study period in 2008, compared to 31 percent of the study period in 1996. A single stream of charged particles can last for as long as 7 to 10 days. At their peak, the accumulated impact of the streams during one year can inject as much energy into Earth's environment as massive eruptions from the Sun's surface can during a year at the peak of a solar cycle, says co-author Janet Kozyra of the University of Michigan.
The streams strike Earth periodically, spraying out in full force like water from a fire hose as the Sun revolves. When the magnetic fields in the solar winds point in a direction opposite to the magnetic lines in Earth's magnetosphere, they have their strongest effect. The strength and speed of the magnetic fields in the high-speed streams can also affect Earth's response.
The authors speculate that the high number of low-latitude coronal holes during this solar minimum may be related to a weakness in the Sun's overall magnetic field. The Sun in 2008 had smaller polar coronal holes than in 1996, but high-speed streams that escape from the Sun's poles do not travel in the direction of Earth.
"The Sun-Earth interaction is complex, and we haven't yet discovered all the consequences for the Earth's environment of the unusual solar winds this cycle," Kozyra says. "The intensity of magnetic activity at Earth in this extremely quiet solar minimum surprised us all. The new observations from last year are changing our understanding of how solar quiet intervals affect the Earth and how and why this might change from cycle to cycle."
Journal reference:
Sarah Gibson, Janet Kozyra, Giuliana de Toma, Barbara Emory, Terry Onsager, and Barbara Thompson. If the Sun is so quiet, why is the Earth ringing? A comparison of two solar minimum intervals. Journal of Geophysical Research, 2009; 114 (a9): A09105 DOI: 10.1029/2009JA014342
Adapted from materials provided by National Center for Atmospheric Research/University Corporation for Atmospheric Research.

Jupiter Pummeled, Leaving Bruise The Size Of Pacific Ocean

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ScienceDaily (July 21, 2009) — Scientists have found evidence that another object has bombarded Jupiter, exactly 15 years after the first impacts by the comet Shoemaker-Levy 9.

Following up on a tip by an amateur astronomer, Anthony Wesley of Australia, that a new dark "scar" had suddenly appeared on Jupiter, this morning between 3 and 9 a.m. PDT (6 a.m. and noon EDT) scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., using NASA's Infrared Telescope Facility at the summit of Mauna Kea, Hawaii, gathered evidence indicating an impact.
New infrared images show the likely impact point was near the south polar region, with a visibly dark "scar" and bright upwelling particles in the upper atmosphere detected in near-infrared wavelengths, and a warming of the upper troposphere with possible extra emission from ammonia gas detected at mid-infrared wavelengths.
"We were extremely lucky to be seeing Jupiter at exactly the right time, the right hour, the right side of Jupiter to witness the event. We couldn't have planned it better," said Glenn Orton, a scientist at JPL.
Orton and his team of astronomers kicked into gear early in the morning and haven't stopped tracking the planet. They are downloading data now and are working to get additional observing time on this and other telescopes.
This image was taken at 1.65 microns, a wavelength sensitive to sunlight reflected from high in Jupiter's atmosphere, and it shows both the bright center of the scar (bottom left) and the debris to its northwest (upper left).
"It could be the impact of a comet, but we don't know for sure yet," said Orton. "It's been a whirlwind of a day, and this on the anniversary of the Shoemaker-Levy 9 and Apollo anniversaries is amazing."
Shoemaker-Levy 9 was a comet that had been seen to break into many pieces before the pieces hit Jupiter in 1994.
Leigh Fletcher, a NASA postdoctoral fellow at JPL who worked with Orton during these latest observations said, "Given the rarity of these events, it's extremely exciting to be involved in these observations. These are the most exciting observations I've seen in my five years of observing the outer planets!"
The observations were made possible in large measure by the extraordinary efforts of the Infrared Telescope Facility staff, including telescope operator William Golisch, who adroitly moved three instruments in and out of the field during the short time the scar was visible on the planet, providing the wide wavelength coverage.
JPL is managed for NASA by the California Institute of Technology in Pasadena.
Adapted from materials provided by NASA/Jet Propulsion Laboratory.

Eagle Nebula: An Eagle Of Cosmic Proportions

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ScienceDaily (July 17, 2009) — Located 7000 light-years away, towards the constellation of Serpens (the Snake), the Eagle Nebula is a dazzling stellar nursery, a region of gas and dust where young stars are currently being formed and where a cluster of massive, hot stars, NGC 6611, has just been born.

The powerful light and strong winds from these massive new arrivals are shaping light-year long pillars, seen in the image partly silhouetted against the bright background of the nebula. The nebula itself has a shape vaguely reminiscent of an eagle, with the central pillars being the “talons”.
The star cluster was discovered by the Swiss astronomer, Jean Philippe Loys de Chéseaux, in 1745–46. It was independently rediscovered about twenty years later by the French comet hunter, Charles Messier, who included it as number 16 in his famous catalogue, and remarked that the stars were surrounded by a faint glow. The Eagle Nebula achieved iconic status in 1995, when its central pillars were depicted in a famous image obtained with the NASA/ESA Hubble Space Telescope. In 2001, ESO’s Very Large Telescope (VLT) captured another breathtaking image of the nebula (ESO Press Photo 37/01), in the near-infrared, giving astronomers a penetrating view through the obscuring dust, and clearly showing stars being formed in the pillars.
The newly released image, obtained with the Wide-Field Imager camera attached to the MPG/ESO 2.2-metre telescope at La Silla, Chile, covers an area on the sky as large as the full Moon, and is about 15 times more extensive than the previous VLT image, and more than 200 times more extensive than the iconic Hubble visible-light image. The whole region around the pillars can now be seen in exquisite detail.
The “Pillars of Creation” are in the middle of the image, with the cluster of young stars, NGC 6611, lying above and to the right. The “Spire” — another pillar captured by Hubble — is at the centre left of the image.
Finger-like features protrude from the vast cloud wall of cold gas and dust, not unlike stalagmites rising from the floor of a cave. Inside the pillars, the gas is dense enough to collapse under its own weight, forming young stars. These light-year long columns of gas and dust are being simultaneously sculpted, illuminated and destroyed by the intense ultraviolet light from massive stars in NGC 6611, the adjacent young stellar cluster. Within a few million years — a mere blink of the universal eye — they will be gone forever.
Adapted from materials provided by European Southern Observatory - ESO.

Primitive Asteroids In The Main Asteroid Belt May Have Formed Far From The Sun

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ScienceDaily (July 15, 2009) — Many of the objects found today in the asteroid belt located between the orbits of Mars and Jupiter may have formed in the outermost reaches of the solar system, according to an international team of astronomers led by scientists from Southwest Research Institute (SwRI).

The team used numerical simulations to show that some comet-like objects residing in a disk outside the original orbit of the planets were scattered across the solar system and into the outer asteroid belt during a violent phase of planetary evolution.
Usually, the solar system is considered a place of relative permanence, with changes occurring gradually over hundreds of millions to billions of years. New models of planet formation indicate, however, that at specific times, the architecture of the solar system experienced dramatic upheaval.
In particular, it now seems probable that approximately 3.9 billion years ago, the giant planets of our solar system -- Jupiter, Saturn, Uranus and Neptune -- rearranged themselves in a tumultuous spasm. "This last major event of planet formation appears to have affected nearly every nook and cranny of the solar system," says lead author Dr. Hal Levison of SwRI.
Key evidence for this event was first identified in the samples returned from the Moon by the Apollo astronauts. They tell us about an ancient cataclysmic bombardment where large asteroids and comets rained down on the Moon.
Scientists now recognize that this event was not limited solely to the Moon; it also affected the Earth and many other solar system bodies. "The existence of life on Earth, as well as the conditions that made our world habitable for us, are strongly linked to what happened at this distant time," states Dr. David Nesvorny of SwRI.
The same dynamical conditions that devastated the planets also led to the capture of some would-be impactors in the asteroid belt. "In the classic movie 'Casablanca,' everybody comes to Rick's. Apparently throughout the solar system, the cool hangout for small objects is the asteroid belt," says Dr. William Bottke of SwRI.
Once in the asteroid belt, the embedded comet-like objects began to beat up both themselves and the asteroids. "Our model shows that comets are relatively easy to break up when hit by something, at least when compared to typical asteroids. It is unavoidable that some of the debris went on to land on asteroids, the Moon and the Earth. In fact, some of the leftovers may still be arriving today," says Dr. Alessandro Morbidelli of the Observatoire de la Cote d'Azur in Nice, France.
The team believes the surprising similarities between some micrometeorites landing on Earth and comet samples returned by NASA's Stardust mission are no accident. "There has been lots of debate about the nature of micrometeorites reaching the Earth," says Dr. Matthieu Gounelle of the Museum National d'Histoire Naturelle in Paris. "Some believe they are asteroidal, while others argue they are cometary. Our work suggests that in a sense, both camps may be right."
"Some of the meteorites that once resided in the asteroid belt show signs they were hit by 3.5 to 3.9 billion years ago. Our model allows us to make the case they were hit by captured comets or perhaps their fragments," adds Dr. Kleomenis Tsiganis of Aristotle University of Thessaloniki, Greece. "If so, they are telling us the same intriguing story as the lunar samples, namely that the solar system apparently went berserk and reconfigured itself about 4 billion years ago."
Overall, the main asteroid belt contains a surprising diversity of objects ranging from primitive ice/rock mixtures to igneous rocks. The standard model used to explain this assumes that most asteroids formed in place from a primordial disk that experienced radical chemical changes within this zone. This model shows, however, that the observed diversity of the asteroid belt is not a direct reflection of the intrinsic compositional variation of the proto-planetary disk. These results fundamentally change our view of the asteroid belt.
Additional tests of this model will come from studies of meteorites, the asteroid belt, planet formation and the Moon. "The Moon and the asteroid belt may be the best and most accessible places in the solar system to understand this critical part of solar system history," says Levison. "We believe key evidence from these cold airless bodies may help us unlock the biggest 'cold case' of all time."
Funding for this research was provided by NASA's Outer Planets Research and Origins of Solar Systems programs. Additional support was provided by NASA's Lunar Science Institute.
Journal reference:
Levison et al. Contamination of the asteroid belt by primordial trans-Neptunian objects. Nature, 2009; 460 (7253): 364 DOI: 10.1038/nature08094
Adapted from materials provided by Southwest Research Institute, via EurekAlert!, a service of AAAS.

How Saturn's Moon Got Its Stripes

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ScienceDaily (July 15, 2009) — A new study has revealed the origins of tiger stripes and a subsurface ocean on Enceladus- one of Saturn’s many moons. These geological features are believed to be the result of the moon’s unusual chemical composition and not a hot core, shedding light on the evolution of planets and guiding future space exploration.

Dr Dave Stegman, a Centenary Research Fellow in the School of Earth Sciences at the University of Melbourne, led the study and says that part of the intrigue with Enceladus is that it was once presumed to be a lifeless, frozen ice ball until a water vapour plume was seen erupting from its surface in 2006.
“NASA’s Cassini spacecraft recently revealed Enceladus as a dynamic place, recording geological features such as geysers emerging from the ‘tiger stripes’ which are thought to be cracks caused by tectonic activity on the south pole of the moon’s surface,” says Dr Stegman.
The moon is also one of the brightest objects in our solar system because the ice covering its surface reflects almost 100 percent of the sunlight that strikes it. One of Saturn’s 53 moons (so far identified) Enceladus reflects so much of the sun’s energy that its surface temperature is about -201° C (-330° F).
Grappling with how an inaccessible small moon with a completely frozen interior was capable of displaying geological activity, Dr Stegman and colleagues used computer simulations to virtually explore it.
Ammonia, usually found on Earth as an odorous gas used to make fertilizers, has been indirectly observed to be present in Enceladus and formed the basis of the study which is the first to reveal the origins of the subsurface ocean.
The model reveals that Enceladus initially had a frozen shell composed of a mixture of ammonia and water ice surrounding a rocky core. Over time, as Enceladus interacted with other moons, a small amount of heat was generated above the silicate core which made the ice shell separate into chemically distinct layers. An ammonia-enriched liquid layer formed on top of the core while a thin layer of pure water ice formed above that. The work will be published in the August issue of the planetary science journal, Icarus.
“We found that if a layer of pure water ice formed near the core, it would have enough buoyancy to rise upwards, and such a redistribution of mass can generate large tectonic stresses at the surface,” says Dr Stegman. “However, the pure water ice rising up is also slightly warmer which causes the separation to occur again, this time forming an ammonia-enriched ocean just under the surface. The presence of ammonia, which acts as an anti-freeze, then helps keep the ocean in its liquid state.”
“These simulations are an important step in understanding how planets evolve and provide questions to focus future space exploration and observations. It will hopefully progress our understanding of how and why planets and moons are different to each other.”
Adapted from materials provided by University of Melbourne.

New Map Hints At Venus's Wet, Volcanic Past

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ScienceDaily (July 14, 2009) — Venus Express has charted the first map of Venus's southern hemisphere at infrared wavelengths. The new map hints that our neighbouring world may once have been more Earth-like, with both, a plate tectonics system and an ocean of water.

The map comprises over a thousand individual images, recorded between May 2006 and December 2007. Because Venus is covered in clouds, normal cameras cannot see the surface, but Venus Express used a particular infrared wavelength that can see through them.
Although radar systems have been used in the past to provide high-resolution maps of Venus's surface, Venus Express is the first orbiting spacecraft to produce a map that hints at the chemical composition of the rocks. The new data is consistent with suspicions that the highland plateaus of Venus are ancient continents, once surrounded by ocean and produced by past volcanic activity.
"This is not proof, but it is consistent. All we can really say at the moment is that the plateau rocks look different from elsewhere," says Nils Müller at the Joint Planetary Interior Physics Research Group of the University Münster and DLR Berlin, who headed the mapping efforts.
The rocks look different because of the amount of infrared light they radiate into space, similar to the way a brick wall heats up during the day and gives off its heat at night. Besides, different surfaces radiate different amounts of heat at infrared wavelengths due to a material characteristic known as emissivity, which varies in different materials. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument captured this infrared radiation during Venus's night-time orbits around the planet's southern hemisphere.
The eight Russian landers of the 1970s and 1980s touched down away from the highlands and found only basalt-like rock beneath their landing pads. The new map shows that the rocks on the Phoebe and Alpha Regio plateaus are lighter in colour and look old compared to the majority of the planet. On Earth, such light-coloured rocks are usually granite and form continents.
Granite is formed when ancient rocks, made of basalt, are driven down into the planet by shifting continents, a process known as plate tectonics. The water combines with the basalt to form granite and the mixture is reborn through volcanic eruptions.
"If there is granite on Venus, there must have been an ocean and plate tectonics in the past," says Müller.
Müller points out that the only way to know for sure whether the highland plateaus are continents is to send a lander there. Over time, Venus's water has been lost to space, but there might still be volcanic activity. The infrared observations are very sensitive to temperature. But in all images they saw only variations of between 3-20°C, instead of the kind of temperature difference they would expect from active lava flows.
Although Venus Express did not see any evidence of ongoing volcanic activity this time this time around, Müller does not rule it out. "Venus is a big planet, being heated by radioactive elements in its interior. It should have as much volcanic activity as Earth," he says. Indeed, some areas do appear to be composed of darker rock, which hints at relatively recent volcanic flows.
The new map gives astronomers another tool in their quest to understand why Venus is so similar in size to Earth and yet has evolved so differently.
Adapted from materials provided by European Space Agency.

Turbulence Responsible For Black Holes' Balancing Act

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ScienceDaily (July 14, 2009) — We live in a hierarchical Universe where small structures join into larger ones. Earth is a planet in our Solar System, the Solar System resides in the Milky Way Galaxy, and galaxies combine into groups and clusters. Clusters are the largest structures in the Universe, but sadly our knowledge of them is not proportional to their size.

Researchers have long known that the gas in the centers of some galaxy clusters is rapidly cooling and condensing, but were puzzled why this condensed gas did not form into stars. Until recently, no model existed that successfully explained how this was possible.
Evan Scannapieco, a theoretical astrophysicist, has spent much of his career studying the evolution of galaxies and clusters. "There are two types of clusters: cool-core clusters and non-cool core clusters," he explains. "Non-cool core clusters haven't been around long enough to cool, whereas cool-core clusters are rapidly cooling, although by our standards they are still very hot."
Scannapieco is an assistant professor in Arizona State University's School of Earth and Space Exploration in the College of Liberal Arts and Sciences.
X-ray telescopes have revolutionized our understanding of the activity occurring within cool-core clusters. Although these clusters can contain hundreds or even thousands of galaxies, they are mostly made up of a diffuse, but very hot gas known as the intracluster medium. This intergalactic gas is only visible to X-ray telescopes, which are able to map out its temperature and structure. These observations show that the diffuse gas is rapidly cooling into the centers of cool-core clusters.
At the core of each of these clusters is a black hole, billions of times more massive than the Sun. Some of the cooling medium makes its way down to a dense disk surrounding this black hole, some of it goes into the black hole itself, and some of it is shot outward. X-ray images clearly show jet-like bursts of ejected material, which occur in regular cycles.
But why were these outbursts so regular, and why did the cooling gas never drop to colder temperatures that lead to the formation of stars? Some unknown mechanism was creating an impressive balancing act.
"It looked like the jets coming from black holes were somehow responsible for stopping the cooling," says Scannapieco, "but until now no one was able to determine exactly how."
Scannapieco and Marcus Brüggen, a professor at Jacobs University in Bremen, Germany, used the powerful supercomputers at ASU to develop their own three-dimensional simulation of the galaxy cluster surrounding one of the Universe's biggest black holes. By adapting an approach developed by Guy Dimonte at Los Alamos National Laboratory and Robert Tipton at Lawrence Livermore National Laboratory, Scannapieco and Brüggen added the component of turbulence to the simulations, which was never accounted for in the past.
That was the key ingredient.
Turbulence works in partnership with the black hole to maintain the balance. Without the turbulence, the jets coming from around black hole would grow stronger and stronger, and the gas would cool catastrophically into a swarm of new stars. When turbulence is accounted for, the black hole not only balances the cooling, but goes through regular cycles of activity.
"When you have turbulent flow, you have random motions on all scales," explains Brüggen. "Each jet of material ejected from the disk creates turbulence that mixes everything together."
Scannapieco and Brüggen's results, to be published in the journal Monthly Notices of the Royal Astronomical Society, reveal that turbulence acts to effectively mix the heated region with its surroundings so that the cool gas can't make it down to the black hole, thus preventing star formation.
Every time some cool gas reaches the black hole, it is shot out in a jet. This generates turbulence that mixes the hot gas with the cold gas. This mixture becomes so hot that it doesn't accrete onto the black hole. The jet stops and there is nothing to drive the turbulence so it fades away. At that point, the hot gas no longer mixes with the cold gas, so the center of the cluster cools, and more gas makes its way down to the black hole.
Before long, another jet forms and the gas is once again mixed together.
"We improved our simulations so that they could capture those tiny turbulent motions," explains Scannapieco. "Even though we can't see them, we can estimate what they would do. The time it takes for the turbulence to decay away is exactly the same amount of time observed between the outbursts."
Adapted from materials provided by Arizona State University, via EurekAlert!, a service of AAAS.

Herschel has carried out the first test observations with all its instruments, with spectacular results.

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ScienceDaily (July 13, 2009) — Herschel has carried out the first test observations with all its instruments, with spectacular results. Galaxies, star-forming regions and dying stars comprised the telescope’s first targets. The instruments provided spectacular data at their first attempt, finding water, carbon and revealing dozens of distant galaxies.

These observations show that Herschel’s instruments are working beyond expectations. They promise a mission of rich discoveries for waiting astronomers.
SPIRE surprises with power
On 24 June, Herschel’s Spectral and Photometric Imaging Receiver (SPIRE) was trained on two galaxies for its first look at the Universe. The galaxies showed up prominently, providing astronomers with their best images yet at these wavelengths, and revealing other more distant galaxies in the background of the images.
The pictures show galaxies M66 and M74 at a wavelength of 250 microns, longer than any previous infrared space observatory, but still the shortest SPIRE wavelength.
SPIRE is designed to look at star formation in our own Galaxy and in nearby galaxies. It will also search for star-forming galaxies in the very distant Universe. Because these galaxies are so far away, their light has taken a very long time to reach us, so by detecting them we are looking into the past and learning how and when galaxies like our own were formed.
Herschel’s primary mirror is 3.5 m in diameter, nearly four times larger than any previous infrared space telescope. These images prove that it represents a giant leap forward in our ability to study celestial objects at far infrared wavelengths.
Spitzer primarily observes shorter infrared wavelengths than Herschel, so the two telescopes complement each other.
These observations were all made on the first day that SPIRE was used. They clearly show that the main scientific studies planned with the instrument are going to work extremely well.
Water-hunter HIFI scores at first try
Scientists used Herschel’s Heterodyne Instrument for the Far-Infrared (HIFI) on 22 June to look for warm molecular gas heated by newborn massive stars in the DR21 star-forming region in Cygnus.
HIFI provided excellent data in two different observing modes, returning information on the composition of the region with unprecedented accuracy and resolution. It works by ‘zooming in’ on specific wavelengths, revealing different spectral ‘lines’ that represent the fingerprints of atoms and molecules and even the physical conditions of the object observed. This makes it a powerful tool to study the role of gas and dust in the formation of stars and planets and the evolution of galaxies.
Using HIFI, scientists observed ionised carbon, carbon monoxide, and water in DR21. These different molecular lines add their pieces to a more complete understanding of what is happening.
The high quality of these first observations promises great new insights into the process of star formation.
PACS stares into the Cat’s Eye
The first observation with the Photodetector Array Camera and Spectrometer (PACS) instrument was carried out on 23 June.
The first target was the dying star known as the Cat's Eye Nebula. Discovered by William Herschel in 1786, this nebula consists of a complex shell of gas thrown off by a dying star. Dying stars create spectacular nebulae, enriching the interstellar medium with heavy chemical elements. But how does an initially spherical star produce such a complex nebula? To solve this question we need to look at the processes close to the star, where the matter is ejected.
With the PACS spectrometer it is now possible for the first time to make images in spectral lines for on the sky, and see how the wind from the star shapes the nebula in three dimensions. The PACS spectrometer was used to look into the Cat’s eye. This mode records the composition and condition of celestial objects at precisely defined wavelengths.
PACS observed the nebula in two spectral lines from ionised nitrogen and oxygen. For better orientation, the PACS photometer took a small map of the Cat’s Eye Nebula in its 70 micron band, showing the structure of a dust ring with an opening on one side.
Following these first light images, Herschel is now in the performance verification phase, where the instruments will be further tested and calibrated. This phase will last until the end of November, after which the mission will begin its routine science phase. These images show that there is a lot of science to look forward to.
Adapted from materials provided by European Space Agency.

Antimatter Positrons Explain Gamma Ray Mystery In Milky Way Galaxy

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ScienceDaily (July 8, 2009) — A team of astrophysicists has solved a mystery that led some scientists to speculate that the distribution of certain gamma rays in our Milky Way galaxy was evidence of a form of undetectable “dark matter” believed to make up much of the mass of the universe.

In two separate scientific papers, the most recent of which appears in the July 10 issue of the journal Physical Review Letters, the astrophysicists show that this distribution of gamma rays can be explained by the way “antimatter positrons” from the radioactive decay of elements, created by massive star explosions in the galaxy, propagate through the galaxy. Thus, the scientists said, the observed distribution of gamma rays is not evidence for dark matter.
“There is no great mystery,” said Richard Lingenfelter, a research scientist at UC San Diego’s Center for Astrophysics and Space Sciences who conducted the studies with Richard Rothschild, a research scientist also at UCSD, and James Higdon, a physics professor at the Claremont Colleges. “The observed distribution of gamma rays is in fact quite consistent with the standard picture.”
Over the past five years, gamma ray measurements from the European satellite INTEGRAL have perplexed astronomers, leading some to argue that a “great mystery” existed because the distribution of these gamma rays across different parts of the Milky Way galaxy was not as expected.
To explain the source of this mystery, some astronomers had hypothesized the existence of various forms of dark matter, which astronomers suspect exists—from the unusual gravitational effects on visible matter such as stars and galaxies—but have not yet found.
What is known for certain is that our galaxy—and others—are filled with tiny subatomic particles known as positrons, the antimatter counterpart of typical, everyday electrons. When an electron and positron encounter each other in space, the two particles annihilate and their energy is released as gamma rays. That is, the electron and positron disappear and two or three gamma rays appear.
”These positrons are born at nearly the speed of light, and travel thousands of light years before they slow down enough in dense clouds of gas to have a chance of joining with an electron to annihilate in a dance of death,” explains Higdon. “Their slowing down occurs from the drag of other particles during their journey through space. Their journey is also impeded by the many fluctuations in the galactic magnetic field that scatter them back and forth as they move along. All of this must be taken into account in calculating the average distance the positrons would travel from their birthplaces in supernova explosions.”
”Some positrons head towards the center of the Galaxy, some towards the outer reaches of the Milky Way known as the galactic halo, and some are caught in the spiral arms,” said Rothschild. “While calculating this in detail is still far beyond the fastest supercomputers, we were able to use what we know about how electrons travel throughout the solar system and what can be inferred about their travel elsewhere to estimate how their anti-matter counterparts permeate the galaxy.”
The scientists calculated that most of the gamma rays should be concentrated in the inner regions of the galaxy, just as was observed by the satellite data, the team reported in a paper published last month in the Astrophysical Journal.
“The observed distribution of gamma rays is consistent with the standard picture where the source of positrons is the radioactive decay of isotopes of nickel, titanium and aluminum produced in supernova explosions of stars more massive than the Sun,” said Rothschild.
In their companion paper in this week’s issue of Physical Review Letters, the scientists point out that a basic assumption of one of the more exotic explanations for the purported mystery—dark matter decays or annihilations—is flawed, because it assumes that the positrons annihilate very close to the exploding stars from which they originated.
“We clearly demonstrated this was not the case, and that the distribution of the gamma rays observed by the gamma ray satellite was not a detection or indication of a ‘dark matter signal’,” said Lingenfelter.
The scientists were supported in their studies by grants from the National Aeronautics and Space Administration.
Adapted from materials provided by University of California/San Diego.

Dozens Of Newly Discovered Pulsars Probed By NASA's Fermi Gamma-ray Space Telescope

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ScienceDaily (July 7, 2009) — With NASA's Fermi Gamma-ray Space Telescope, astronomers now are getting their best look at those whirling stellar cinders known as pulsars. In two studies published in the July 2 edition of Science Express, international teams have analyzed gamma-rays from two dozen pulsars, including 16 discovered by Fermi. Fermi is the first spacecraft able to identify pulsars by their gamma-ray emission alone.

A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Most of the 1,800 cataloged pulsars were found through their periodic radio emissions. Astronomers believe these pulses are caused by narrow, lighthouse-like radio beams emanating from the pulsar's magnetic poles.
"Fermi has truly unprecedented power for discovering and studying gamma-ray pulsars," said Paul Ray of the Naval Research Laboratory in Washington. "Since the demise of the Compton Gamma Ray Observatory a decade ago, we've wondered about the nature of unidentified gamma-ray sources it detected in our galaxy. These studies from Fermi lift the veil on many of them."
The Vela pulsar, which spins 11 times a second, is the brightest persistent source of gamma rays in the sky. Yet gamma rays -- the most energetic form of light -- are few and far between. Even Fermi's Large Area Telescope sees only about one gamma-ray photon from Vela every two minutes.
"That's about one photon for every thousand Vela rotations," said Marcus Ziegler, a member of the team reporting on the new pulsars at the University of California, Santa Cruz. "From the faintest pulsar we studied, we see only two gamma-ray photons a day."
Radio telescopes on Earth can detect a pulsar easily only if one of the narrow radio beams happens to swing our way. If not, the pulsar can remain hidden.
A pulsar's radio beams represent only a few parts per million of its total power, whereas its gamma rays account for 10 percent or more. Somehow, pulsars are able to accelerate particles to speeds near that of light. These particles emit a broad beam of gamma rays as they arc along curved magnetic field lines.
The new pulsars were discovered as part of a comprehensive search for periodic gamma-ray fluctuations using five months of Fermi Large Area Telescope data and new computational techniques.
"Before launch, some predicted Fermi might uncover a handful of new pulsars during its mission," Ziegler added. "To discover 16 in its first five months of operation is really beyond our wildest dreams."
Like spinning tops, pulsars slow down as they lose energy. Eventually, they spin too slowly to power their characteristic emissions and become undetectable.
But pair a slowed dormant pulsar with a normal star, and a stream of stellar matter from the companion can spill onto the pulsar and increase its spin. At rotation periods between 100 and 1,000 times a second, ancient pulsars can resume the activity of their youth. In the second study, Fermi scientists examined gamma rays from eight of these "born-again" pulsars, all of which were previously discovered at radio wavelengths.
"Before Fermi launched, it wasn't clear that pulsars with millisecond periods could emit gamma rays at all," said Lucas Guillemot at the Center for Nuclear Studies in Gradignan, near Bordeaux, France. "Now we know they do. It's also clear that, despite their differences, both normal and millisecond pulsars share similar mechanisms for emitting gamma rays."
NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.
Adapted from materials provided by NASA/Goddard Space Flight Center.

International Space Hotel Envisioned

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ScienceDaily (July 6, 2009) — Plans for a new international space hotel have been unveiled by students this month as part of a project for their Masters degree in Innovation Design Engineering (IDE).

Students from the course have developed plans for a hotel that could be built in space and fitted to the International Space Station, which is currently orbiting the Earth. The Masters in IDE is run jointly by Imperial College London and the Royal College of Art.
On June 26, the students unveiled a 12 metre-long replica of the hotel interior, together with animated computer designs that showed what the inside of the space hotel would look and feel like for tourists.
For the project, students had to grapple with the challenges of designing that could function in a zero gravity environment. They worked with visiting lecturer and space architecture expert Daniele Bedini, who has worked for the National Aeronautical Space Agency (NASA) and the European Space Agency (ESA) on projects for a Moon base and new missions to Mars.
“Designing a building that is floating hundreds of miles above Earth throws up all kinds of engineering challenges,” said Bedini. “From personal hygiene to sleeping in zero gravity, we encouraged the students to be completely creative with their solutions so that the living conditions in the world’s most isolated hotel could be as comfortable as possible.”
The students designed smaller toilets that would save space and that would also have the suction power of a vacuum, to counteract zero gravity and help human muscles to remove waste more effectively. In addition, they devised a shower nozzle that could spit out water when it was pressed on the skin and then suck the water back up again after it had been used for washing. This would stop the water from being left floating as globules in zero gravity.
The students were tasked with creating new fashions that space tourists could wear. IDE student Katrin Baumgarten was part of a team that had to develop new fashion concepts that were comfortable, stylish and practical. She said:
“There are no washing machines or tumble dryers in space so we had to design clothes that enabled the skin to breathe, which reduces sweating, smells and the need for clothes to be washed. We achieved this by using natural fibres that breathe and we also made small chest flaps, which let the air in to keep the body cool and comfortable.”
The students were also challenged with finding new bedding for people sleeping in zero gravity, which could restrain the body without making the sleeper feel claustrophobic. The students designed single and double sleeping bags that were large warm cocoons, with soft elastic covers that could restrain the sleepers, so that people could be comfortable without feeling like they were hemmed in.
The students created a novel solution for tourists wanting to record their trip, designing a 'floating camera' that would be able to move independently in space, to automatically follow the space tourist and document their life on board. The students believe this would be an important aspect of the experience for tourists who would wish to capture their trip for posterity and show it to friends and family on Earth.
Adapted from materials provided by Imperial College London.

Fireworks Display In The Helix Nebula

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ScienceDaily (July 5, 2009) — The Helix Nebula, NGC 7293, is not only one of the most interesting and beautiful planetary nebulae; it is also one of the closest nebulae to Earth, at a distance of only 710 light years away. A new image, taken with an infrared camera on the Subaru Telescope in Hawaii, shows tens of thousands of previously unseen comet-shaped knots inside the nebula. The sheer number of knots -- more than have ever been seen before -- looks like a massive fireworks display in space.

The Helix Nebula was the first planetary nebula in which knots were seen, and their presence may provide clues to what planetary material may survive at the end of a star’s life. Planetary nebulae are the final stages in the lives of low-mass stars, such as our Sun. As they reach the ends of their lives they throw off large amounts of material into space. Although the nebula looks like a fireworks display, the process of developing a nebula is neither explosive nor instantaneous; it takes place slowly, over a period of about 10,000 to 1,000,000 years. This gradual process creates these nebulae by exposing their inner cores, where nuclear burning once took place and from which bright ultraviolet radiation illuminates the ejected material.
Astronomers from the National Astronomical Observatory of Japan (NAOJ), from London, Manchester and Kent universities in the UK and from a university in Missouri in the USA studied the emissions from hydrogen molecules in the infrared and found that knots are found throughout the entire nebula. Although these molecules are often destroyed by ultraviolet radiation in space, they have survived in these knots, shielded by dust and gas that can be seen in optical images. The comet-like shape of these knots results from the steady evaporation of gas from the knots, produced by the strong winds and ultraviolet radiation from the dying star in the center of the nebula.
Unlike previous optical images of the Helix Nebula knots, the infrared image shows thousands of clearly resolved knots, extending out from the central star at greater distances than previously observed. The extent of the cometary tails varies with the distance from the central star, just as Solar System comets have larger tails when they are closer to the Sun and when wind and radiation are stronger. “This research shows how the central star slowly destroys the knots and highlights the places where molecular and atomic material can be found in space,”says lead astronomer Dr. Mikako Matsuura, previously at NAOJ and now from University College London.
These images enable astronomers to estimate that there may be as many as 40,000 knots in the entire nebula, each of which are billions of kilometers/miles across. Their total mass may be as much as 30,000 Earths, or one-tenth the mass of our Sun. The origin of the knots is currently unknown. Are they remnants of the star's planetary system or are they material ejected from the star at some stage in its life? Either answer will help astronomers answer important questions about the lives of stars and planetary systems.
The innovative technology of the Subaru Telescope with its near-infrared camera, MOIRCS, enabled researchers to produce such impressive images. Mounted on one of the largest infrared optical telescopes in the world, MOIRCS (Multi-object Infrared Camera and Spectrograph) has a large (4 arcmin by 7 arcmin) field of view, allowing it to capture, with a single shot, such detailed features in a large PN.
This paper will be published in the Astrophysical Journal in August 2009.
Adapted from materials provided by National Astronomical Observatory of Japan.

Fast Neutral Hydrogen Detected Coming From The Moon

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ScienceDaily (July 5, 2009) — NASA's Interstellar Boundary Explorer (IBEX) spacecraft has made the first observations of very fast hydrogen atoms coming from the moon, following decades of speculation and searching for their existence.

During spacecraft commissioning, the IBEX team turned on the IBEX-Hi instrument, built primarily by Southwest Research Institute (SwRI) and the Los Alamos National Laboratory, which measures atoms with speeds from about half a million to 2.5 million miles per hour. Its companion sensor, IBEX-Lo, built by Lockheed Martin, the University of New Hampshire, NASA Goddard Space Flight Center, and the University of Bern in Switzerland, measures atoms with speeds from about one hundred thousand to 1.5 million mph.
"Just after we got IBEX-Hi turned on, the moon happened to pass right through its field of view, and there they were," says Dr. David J. McComas, IBEX principal investigator and assistant vice president of the SwRI Space Science and Engineering Division. "The instrument lit up with a clear signal of the neutral atoms being detected as they backscattered from the moon."
The solar wind, the supersonic stream of charged particles that flows out from the sun, moves out into space in every direction at speeds of about a million mph. The Earth's strong magnetic field shields our planet from the solar wind. The moon, with its relatively weak magnetic field, has no such protection, causing the solar wind to slam onto the moon's sunward side.
From its vantage point in space, IBEX sees about half of the moon -- one quarter of it is dark and faces the nightside (away from the sun), while the other quarter faces the dayside (toward the sun). Solar wind particles impact only the dayside, where most of them are embedded in the lunar surface, while some scatter off in different directions. The scattered ones mostly become neutral atoms in this reflection process by picking up electrons from the lunar surface.
The IBEX team estimates that only about 10 percent of the solar wind ions reflect off the sunward side of the moon as neutral atoms, while the remaining 90 percent are embedded in the lunar surface. Characteristics of the lunar surface, such as dust, craters and rocks, play a role in determining the percentage of particles that become embedded and the percentage of neutral particles, as well as their direction of travel, that scatter.
McComas says the results also shed light on the "recycling" process undertaken by particles throughout the solar system and beyond. The solar wind and other charged particles impact dust and larger objects as they travel through space, where they backscatter and are reprocessed as neutral atoms. These atoms can travel long distances before they are stripped of their electrons and become ions and the complicated process begins again.
The combined scattering and neutralization processes now observed at the moon have implications for interactions with objects across the solar system, such as asteroids, Kuiper Belt objects and other moons. The plasma-surface interactions occurring within protostellar nebula, the region of space that forms around planets and stars -- as well as exoplanets, planets around other stars -- also can be inferred.
IBEX's primary mission is to observe and map the complex interactions occurring at the edge of the solar system, where the million miles per hour solar wind runs into the interstellar material from the rest of the galaxy. The spacecraft carries the most sensitive neutral atom detectors ever flown in space, enabling researchers to not only measure particle energy, but also to make precise images of where they are coming from.
Around the end of the summer, the team will release the spacecraft's first all-sky map showing the energetic processes occurring at the edge of the solar system. The team will not comment until the image is complete, but McComas hints, "It doesn't look like any of the models."
IBEX is the latest in NASA's series of low-cost, rapidly developed Small Explorers spacecraft. The IBEX mission was developed by SwRI with a national and international team of partners. NASA's Goddard Space Flight Center manages the Explorers Program for NASA's Science Mission Directorate.
Journal reference:
McComas, F. Allegrini, P. Bochsler, P. Frisch, H.O. Funsten, M. Gruntman, P.H. Janzen, H. Kucharek, E. Moebius, D.B. Reisenfeld, and N.A. Schwadron. Lunar Backscatter and Neutralization of the Solar Wind: First Observations of Neutral Atoms from the Moon. Geophysical Research Letters, 2009 DOI: 10.1029/2009GL038794
Adapted from materials provided by Southwest Research Institute.

Coolest Spacecraft Ever In Orbit (-273 Degrees Celsius)

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ScienceDaily (July 4, 2009) — On July 2 the detectors of Planck's High Frequency Instrument reached their amazingly low operational temperature of -273°C, making them the coldest known objects in space. The spacecraft has also just entered its final orbit around the second Lagrange point of the Sun-Earth system, L2. Planck is equipped with a passive cooling system that brings its temperature down to about -230°C by radiating heat into space. Three active coolers take over from there, and bring the temperature down further to an amazing low of -273.05°C, only 0.1°C above absolute zero - the coldest temperature theoretically possible in our Universe.

Such low temperatures are necessary for Planck’s detectors to study the Cosmic Microwave Background (CMB), the first light released by the universe only 380 000 yrs after the Big Bang, by measuring its temperature across the sky.
Like measuring the heat of a rabbit on the Moon
The detectors will look for variations in the temperature of the CMB that are about a million times smaller than one degree – this is comparable to measuring from Earth the heat produced by a rabbit sitting on the Moon. This is why the detectors must be cooled to temperatures close to absolute zero (–273.15°C, or zero Kelvin, 0K).
Details on the different stages of the cool-down process are available via the 'Planck in depth' link at right.
Arriving at L2
Starting at 13:15 CEST July 2, the Planck Mission Control Team conducted a crucial orbit insertion manoeuvre designed to place the satellite into its final orbit about L2.
Once commanded, the burn was auto-controlled by Planck, with the thrusters operating for between 12 and 24 hours. The manoeuvre directed the satellite into its final operational orbit around the second Lagrange point of the Sun-Earth system, L2.
The thruster burn was planned to deliberately under-perform by a small margin, necessitating a small 'touch up' manoeuvre in the coming days to bring the satellite fully onto its planned trajectory.
"While this manoeuvre itself is routine, it represents the final major step in the long voyage to L2, and everyone here is quite happy to see Planck getting into its operational orbit," said Chris Watson, Spacecraft Operations Manager, speaking in the mission's Dedicated Control Room at ESA’s European Space Operations Centre, Darmstadt, Germany.
The manoeuvre was planned to change the satellite’s speed by 211.6 km/hour, ending with a final speed of 1010 Km/hour with respect to the ground. Together with Earth and the virtual point L2, Planck will then be orbiting the Sun at a speed of 106 254 km/hour (29.5 km/second).
At the start of yesterday’s manoeuvre, Planck was located 1.43 million km from Earth.
Science operations to begin soon
All commissioning activities are on schedule, and this phase of the mission is practically complete. Over the next few weeks, the operation of the instruments will be fine-tuned for best performance.
Planck will begin to survey the sky in mid-August.
Adapted from materials provided by European Space Agency.

Super-energetic Bursts Discovered Near Giant Black Hole

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ScienceDaily (July 4, 2009) — Using a worldwide combination of diverse telescopes, astronomers have discovered that a giant galaxy's bursts of very high energy gamma rays are coming from a region very close to the supermassive black hole at its core. The discovery provides important new information about the mysterious workings of the powerful "engines" in the centers of innumerable galaxies throughout the Universe.

The galaxy M87, 50 million light-years from Earth, harbors at its center a black hole more than six billion times more massive than the Sun. Black holes are concentrations of matter so dense that not even light can escape their gravitational pull. The black hole is believed to draw material from its surroundings -- material that, as it falls toward the black hole, forms a tightly-rotating disk.
Processes near this "accretion disk," powered by the immense gravitational energy of the black hole, propel energetic material outward for thousands of light-years. This produces the "jets" seen emerging from many galaxies. In 1998, astronomers found that M87 also was emitting flares of gamma rays a trillion times more energetic than visible light.
However, the telescopes that discovered these bursts of very high energy gamma rays could not determine exactly where in the galaxy they originated. In 2007 and 2008, the astronomers using these gamma-ray telescopes combined forces with a team using the National Science Foundation's continent-wide Very Long Baseline Array (VLBA), a radio telescope with extremely high resolving power, or ability to see fine detail.
"Combining the gamma-ray observations with the supersharp radio 'vision' of the VLBA allowed us to see that the gamma rays are coming from a region very near the black hole itself," said Craig Walker, of the National Radio Astronomy Observatory (NRAO).
"Pinning down this location addresses what was an open question and provides important clues for understanding how such highly energetic emissions are produced in the jets of active galaxies," said Matthias Beilicke, of Washington University in St. Louis, MO.
The gamma-ray flares from the galaxy were monitored by systems of large telescopes designed to detect faint flashes of blue light that result when gamma rays enter the Earth's atmosphere. Data from sensitive cameras in these systems can allow astronomers to infer the energy of the gamma rays and the direction from which they came. Their directional information, however, is not precise enough to narrow down the gamma-ray-emitting region within the galaxy.
The VLBA offered a millionfold improvement in resolving power, allowing the scientists to determine that the gamma rays are coming from the immediate vicinity of the black hole. Though gamma rays are the most energetic form of electromagnetic radiation and radio waves the least energetic, both often arise from the same regions. This was shown clearly when M87's most energetic gamma-ray flares were accompanied by the largest flare of radio waves seen from that galaxy by the VLBA.
The radio flare began at about the time of the gamma-ray flares, but continued to increase in brightness for at least two months. "This tells us that energetic material burst out very close to the black hole, causing the gamma rays to be emitted and the radio flare to begin. As that material traveled down the jet, expanding and losing energy, the gamma-ray emission ceased, but the radio continued to increase in brightness," Walker explained. "The VLBA showed us with great precision where the radio emission came from, so we know the gamma rays came from closer in toward the black hole," he added.
M87 is the largest galaxy in the Virgo Cluster of galaxies, at the center of a supercluster of galaxies that includes the Local Group, of which our own Milky Way is a member. The black hole in M87 has an "event horizon," from which matter cannot escape, roughly twice the size of our Solar System, or a tiny fraction of the size of the entire galaxy. The new measurements indicate that the gamma rays are coming from an area no larger than 50 times the size of the event horizon.
The telescope systems that detected the gamma-ray flares are the VERITAS array in Arizona, the H.E.S.S. system in Namibia, Africa, and the MAGIC system on La Palma in the Canary Islands.
The VLBA is a system of ten radio-telescope antennas stretching from Hawaii to the Caribbean, operated by the NRAO from Socorro, New Mexico. The VLBA offers resolving power equal to the ability to read a newspaper in New York while standing in Los Angeles.
Walker and Beilicke worked with Fred Davies of NRAO and New Mexico Tech, Henric Krawczynski of Washington University, Phil Hardee of the University of Alabama, Bill Junor of Los Alamos National Laboratory, Chun Ly of UCLA, and large research teams from VERITAS, H.E.S.S., and MAGIC. The scientists reported their findings in the July 2 online edition of the journal Science.
Adapted from materials provided by National Radio Astronomy Observatory, via EurekAlert!, a service of AAAS.

Largest Ever Survey Of Very Distant Galaxy Clusters Completed

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ScienceDaily (July 3, 2009) — An international team of researchers led by a UC Riverside astronomer has completed the largest ever survey designed to find very distant clusters of galaxies.

Named the Spitzer Adaptation of the Red-sequence Cluster Survey, "SpARCS" detects galaxy clusters using deep ground-based optical observations from the CTIO 4m and CFHT 3.6m telescopes, combined with Spitzer Space Telescope infrared observations.
In a universe which astronomers believe to be 13.7 billion years old, SpARCS is designed to find clusters, snapped as they appeared long ago in time, when the universe was 6 billion years old or younger.
Clusters of galaxies are rare regions of the universe consisting of hundreds of galaxies containing trillions of stars, plus hot gas and mysterious dark matter. Most of the mass in clusters is actually in the form of invisible dark matter which astronomers are convinced exists because of its influence on the orbits of the visible galaxies.
An example of one of the most massive clusters found in the SpARCS survey is shown in the accompanying image. Seen when the universe was a mere 4.8 billion years old, this is also one of the most distant clusters ever discovered. Many similar-color red cluster galaxies can be seen in the image (the green blobs are stars in our own galaxy, The Milky Way).
"We are looking at massive structures very early in the universe's history," said Gillian Wilson, an associate professor of physics and astronomy who leads the SpARCS project.
The SpARCS survey has discovered about 200 new cluster candidates.
"It is very exciting to have discovered such a large sample of these rare objects," Wilson said. "Although we are catching these clusters at early times, we can tell by their red colors that many of the galaxies we are seeing are already quite old. We will be following up this new sample for years to come, to better understand how clusters and their galaxies form and evolve in the early universe."
A summary of the survey and additional images of newly discovered clusters may be found in two companion papers led by Wilson and Adam Muzzin of Yale University, published in the June 20 issue of The Astrophysical Journal.
The SpARCS team consists of Wilson, who joined UCR in 2007, Ricardo Demarco of UCR; Muzzin of Yale University, Conn.; H.K.C. Yee of the University of Toronto, Canada; Mark Lacy and Jason Surace of the Spitzer Science Center/California Institute of Technology; Henk Hoekstra of Leiden University; Michael Balogh and David Gilbank of the University of Waterloo, Canada; Kris Blindert of the Max Planck Institute for Astronomy, Germany; Subhabrata Majumdar of the Tata Institute of Fundamental Research, India; Jonathan P. Gardner of the Goddard Space Flight Center; Mike Gladders of the University of Chicago; and Carol Lonsdale of the North American ALMA Science Center; Douglas Burke of the Harvard-Smithsonian Center for Astrophysics; Shelly Bursick of the University of Arkansas; Michelle Doherty, Chris Lidman and Piero Rosati of ESO; Erica Ellingson of the University of Colorado; Amalia Hicks of Michigan State University; Alessandro Rettura of Johns Hopkins University; David Shupe of the Herscel Science Center/California Institute of Technology; Paolo Tozzi of the University of Trieste, Italy; Renbin Yan of the University of Toronto; and Tracy Webb of McGill University, Canada.
This work is based in part on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This work is also based on observations obtained with The Cerro Tololo Inter-American Observatory, which is operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation; observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii; and by observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and SECYT (Argentina).
Support for this work was provided, in part, by awards issued by JPL/Caltech, and from Wilson's College of Natural and Agricultural Sciences start-up funds at UCR.
Adapted from materials provided by University of California - Riverside.