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.