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  • richardmitnick 8:21 pm on July 27, 2015 Permalink | Reply
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    From NRAO: “Brown Dwarfs, Stars Share Formation Process, New Study Indicates” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    23 July 2015
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    1
    Artist’s conception of a very young, still-forming brown dwarf, with a disk of material orbiting it, and jets of material ejected outward from the poles of the disk. CREDIT: Bill Saxton, NRAO/AUI/NSF

    Astronomers using the Karl G. Jansky Very Large Array (VLA) have discovered jets of material ejected by still-forming young brown dwarfs.

    NRAO VLA
    NRAO/VLA

    The discovery is the first direct evidence that brown dwarfs, intermediate in mass between stars and planets, are produced by a scaled-down version of the same process that produces stars.

    The astronomers studied a sample of still-forming brown dwarfs in a star-forming region some 450 light-years from Earth in the constellation Taurus, and found that four of them have the type of jets emitted by more-massive stars during their formation. The jets were detected by radio observations with the VLA. The scientists also observed the brown dwarfs with the Spitzer and Herschel space telescopes to confirm their status as very young objects.

    NASA Spitzer Telescope
    NASA/Spitzer

    ESA Herschel
    ESA/Herschel

    “This is the first time that such jets have been found coming from brown dwarfs at such an early stage of their formation, and shows that they form in a way similar to that of stars,” said Oscar Morata, of the Institute of Astronomy and Astrophysics of the Academia Sinica in Taiwan. “These are the lowest-mass objects that seem to form the same way as stars,” he added.

    Brown dwarfs are less massive than stars, but more massive than giant planets such as Jupiter. They have insufficient mass to produce the temperatures and pressures at their cores necessary to trigger the thermonuclear reactions that power “normal” stars. Theorists suggested in the 1960s that such objects should exist, but the first unambiguous discovery of one did not come until 1994.

    A key question has been whether brown dwarfs form like stars or like planets. Stars form when a giant cloud of gas and dust in interstellar space collapses gravitationally, accumulating mass. A disk of orbiting material forms around the young star, and eventually planets form from the material in that disk. In the early stages of star formation, jets of material are propelled outward from the poles of the disk. No such jets mark planet formation, however.

    Previous evidence strongly suggested that brown dwarfs shared the same formation mechanism as their larger siblings, but detecting the telltale jets is an important confirmation. Based on this discovery, “We conclude that the formation of brown dwarfs is a scaled-down version of the process that forms larger stars,” Morata said.

    Morata led an international team of astronomers with members from Asia, Europe, and Latin America. They reported their findings in the Astrophysical Journal.

    See the full article here.

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    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 7:59 pm on July 27, 2015 Permalink | Reply
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    From Yale: “Dust pillars of destruction reveal impact of cosmic wind on galaxy evolution” 

    Yale University bloc

    Yale University

    July 27, 2015
    Jim Shelton

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    This Hubble Space Telescope image of a spiral galaxy in the Coma cluster highlights dust extinction features. (Image courtesy of NASA, ESA, and Roberto Colombari)

    Astronomers have long known that powerful cosmic winds can sometimes blow through galaxies, sweeping out interstellar material and stopping future star formation. Now they have a clearer snapshot of how it happens.

    A Yale University analysis of one such event in a nearby galaxy provides an unprecedented look at the process. The research is described in the Astronomical Journal.

    Specifically, Yale astronomer Jeffrey Kenney looked at the way the cosmic wind is eroding the gas and dust at the leading edge of the galaxy. The wind, or ram pressure, is caused by the galaxy’s orbital motion through hot gas in the cluster. Kenney found a series of intricate dust formations on the disk’s edge, as cosmic wind began to work its way through the galaxy.

    “On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front. But you see remarkable, fine scale structure in the dust front,” Kenney explained. “There are head-tail filaments protruding from the dust front. We think these are caused by dense gas clouds becoming separated from lower density gas.”

    Cosmic wind can easily push low-density clouds of interstellar gas and dust, but not high-density clouds. As the wind blows, denser gas lumps start to separate from the surrounding lower density gas which gets blown downstream. But apparently, the high and low-density lumps are partially bound together, most likely by magnetic fields linking distant clouds of gas and dust.

    “The evidence for this is that dust filaments in the HST (Hubble Space Telescope) image look like taffy being stretched out,” Kenney said. “We’re seeing this decoupling, clearly, for the first time.”

    NASA Hubble Telescope
    NASA/ESA HUbble

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    The leading side of the disk shows the effects of strong ram pressure. (Image courtesy of NASA, ESA, and Roberto Colombari)

    The analysis is based on Hubble images of a spiral galaxy in the Coma cluster, located 300 million light years from Earth.

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    A Sloan Digital Sky Survey/Spitzer Space Telescope mosaic of the Coma Cluster in long-wavelength infrared (red), short-wavelength infrared (green), and visible light. The many faint green smudges are dwarf galaxies in the cluster. Credit: NASA/JPL-Caltech/GSFC/SDSS

    It is the closest high-mass cluster to our solar system. Kenney first saw the images two years ago and realized their possible significance in understanding the way ram pressure strips interstellar material throughout the universe.

    In the 1990s, a famous Hubble photo dubbed “Pillars of Creation” showed columns of dust and gas in the Eagle Nebula that were in the process of forging new stars. The dust filaments Kenney identified are similar in some ways to the “Pillars of Creation,” except they are 1,000 times larger.

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    The “Pillars of Creation” in the Eagle Nebula.

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    This wide-field image of the Eagle Nebula was taken at the National Science Foundation’s 0.9-meter telescope on Kitt Peak with the NOAO Mosaic CCD camera. Located in the constellation of Serpens, the Serpent, the Eagle Nebula is a very luminous open cluster of stars surrounded by dust and gas. The three pillars at the center of the image, made famous in an image by the Hubble Space Telescope, are being sculpted by the intense radiation from the hot stars in the cluster. This image was created by combining emission-line images in Hydrogen-alpha (green), Oxygen [O III] (blue) and Sulfur [S II] (red).

    In both cases, destruction is at least as important as creation. An external force is pushing away most of the gas and dust, therefore destroying most of the cloud, leaving behind only the most dense material — the pillars. But even the pillars don’t last that long.

    Because gas is the raw material for star formation, its removal stops the creation of new stars and planets. In the Eagle Nebula, the pressure arises from intense radiation emitted by nearby massive stars; in the Coma galaxy, it is pressure from the galaxy’s orbital motion through hot gas in the cluster. Although new stars are being born in both kinds of pillars, we are witnessing, in both, the last generation of stars that will form.

    Much of Kenney’s research has focused on the physical interplay of galaxies with their environment.

    “A great deal of galaxy evolution is driven by interactions,” Kenney said. “Galaxies are shaped by collisions and mergers, as well as this sweeping of their gas from cosmic winds. I’m interested in all of these processes.”

    Kenney’s co-authors on the paper are Yale doctoral student Anne Abramson and Hector-Bravo Alfaro from the Universidad de Guanajuato in Mexico.

    See the full article here.

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    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
  • richardmitnick 6:25 pm on July 27, 2015 Permalink | Reply
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    From livescience: “Dark Pion Particles May Explain Universe’s Invisible Matter” 

    Livescience

    July 25, 2015
    Jesse Emspak

    1
    Researchers propose that dark matter is a kind of invisible, intangible version of a pion, or a type of meson — a category of particles made up of quarks and antiquarks.
    Credit: MichaelTaylor

    Dark matter is the mysterious stuff that cosmologists think makes up some 85 percent of all the matter in the universe. A new theory says dark matter might resemble a known particle. If true, that would open up a window onto an invisible, dark matter version of physics.

    The only way dark matter interacts with anything else is via gravity. If you poured dark matter into a bucket, it would go right through it because it doesn’t react to electromagnetism (one reason you can stand on the ground is because the atoms in your feet are repelled by the atoms in the Earth). Nor does dark matter reflect or absorb light. It’s therefore invisible and intangible.

    Scientists were clued into its existence by the way galaxies behaved. The mass of the galaxies calculated from the visible stuff they contained wasn’t enough to keep them bound to each other. Later, observations of gravitational lensing, in which light bends in the presence of gravity fields, showed there was something that made galaxy clusters more massive that couldn’t be seen.

    Invisible pions

    Now, a team of five physicists has proposed that dark matter might be a kind of invisible, intangible version of a pion, a particle that was originally discovered in the 1930s. A pion is a type of meson — a category of particles made up of quarks and antiquarks; neutral pions travel between protons and neutrons and bind them together into atomic nuclei.

    Most proposals about dark matter assume it is made up of particles that don’t interact with each other much — they pass through each other, only gently touching. The name for such particles is weakly interacting massive particles, or WIMPs. Another idea is that dark matter is made up of axions, hypothetical particles that could solve some unanswered questions about the Standard Model of particle physics.

    1
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Axions wouldn’t interact strongly with each other, either.

    The new proposal assumes that the dark matter pions interact much more strongly with each other. When the particles touch, they partially annihilate and turn into normal matter. “It’s a SIMP [strongly interacting massive particle],” said Yonit Hochberg, a postdoctoral researcher at Berkeley and lead author on the study. “Strongly interacting with itself.”

    To annihilate into normal matter, the particles must collide in a “three-to-two” pattern, in which three dark matter particles meet. Some of the dark matter “quarks” that make up the particles annihilate and turn into normal matter, leaving some dark matter behind. With this ratio, the result would leave the right proportion of dark matter to normal matter in the current universe.

    This new explanation suggests that in the early universe the dark pions would have collided with each other, reducing the amount of dark matter. But as the universe expanded the particles would collide less and less often, until now, when they are spread so thinly they hardly ever meet at all.

    The interaction bears a close resemblance to what happens to charged pions in nature. These particles consist of an up quark and an anti-down quark. (Quarks come in six flavors, or types: up, down, top, bottom, charm and strange.) When three pions meet, they partially annihilate and become two pions.

    “[The theory] is based on something similar — something that already happens in nature,” said Eric Kuflik, a postdoctoral researcher at Cornell University in New York and a co-author of the study.

    Different kind of pion

    For the new explanation to work, the dark matter pions would have to be made of something different from normal matter. That’s because anything made of normal quarks simply wouldn’t behave the way dark matter does, at least not in the group’s calculations. (There are theories that strange quarks could make up dark matter).

    Charged pions are made up of an up quark and an anti-down quark, or a down and anti-up quark, while neutral pions are made of an up quark plus an anti-up or a down quark plus an anti-down.

    In the new hypothesis, dark matter pions are made up of dark matter quarks that are held together by dark matter gluons. (Ordinary quarks are held together by normal gluons.) The dark quarks wouldn’t be like the familiar six types, and the dark gluon would, unlike ordinary gluons, have mass, according to the mathematics.

    Dark pions and dwarf galaxies

    Another co-author on the paper, Hitoshi Murayama, professor of physics at the University of California, Berkeley, said the new hypothesis would help explain the density of certain kinds of dwarf galaxies. Computer simulations show dwarf galaxies with very dense center regions, but that isn’t what astronomers see in the sky. “If SIMPs are spread out, the distribution is flatter — it works better,” he said.

    Dan Hooper, a staff scientist at Fermi National Accelerator Laboratory in Illinois, said he isn’t quite convinced that this model of dark matter is necessary to explain the dwarf galaxy conundrum. “There’s a handful of people who say dwarfs don’t look like we expect,” he said. “But do you need some other property to solve that? People have showed it could be the heating of gas.” That is, gas heated at the center of a dwarf galaxy would be less dense.

    The Large Hadron Collider might soon offer some insight into which camp is correct; that strange new “dark pions” are dark matter or that they aren’t and there’s something else. Particle accelerators work by taking atomic nuclei — usually hydrogen but sometimes heavier elements like lead —and smashing them together at nearly the speed of light. The resulting explosion scatters new particles, born of the energy of the collision. In that sense the particles are the “shrapnel.”

    Kuflik said that if there’s “missing” mass (more precisely, mass-energy) from the collision of particles that’s a strong pointer to the kind of dark matter that the researchers are looking for. This is because mass and energy are conserved; if the products of a collision don’t tally up to the same amount of mass and energy you started with, that means there might be a previously unknown particle that escaped detection somewhere.

    Such measurements are hard to do, though, so it will take a lot of sifting through data to see if that happens and what the explanation is.

    Another way to track down dark matter particles might be in a detector made with liquid xenon or germanium, in which electrons would occasionally get knocked off an atom by a passing dark matter particle. There’s already an experiment like that, though, the Large Underground Xenon (LUX) project in South Dakota. It didn’t find anything yet, but it was focused on WIMPs (though it was able to rule out some types). A newer version of the experiment is planned; it might detect other kinds of dark matter particle.

    The team is currently working on a paper outlining the kinds of observations that would detect this kind of dark matter. “We’re currently working on writing up explicit ways these dark pions can interact with ordinary matter,” Hochberg said.

    The study appears in the July 10 issue of the journal Physical Review Letters.

    [The article does not include any deatil as to what sort of equipment was used in this work.]

    See the full article here.

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  • richardmitnick 5:57 pm on July 27, 2015 Permalink | Reply
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    From NOVA: “Agriculture May Have Started 11,000 Years Earlier Than We Thought” 

    PBS NOVA

    NOVA

    Mon, 27 Jul 2015

    The technology that allowed us to build cities and develop specialized vocations may have first started 23,000 years ago in present day Israel—some 11,000 years earlier than expected—but then mysteriously disappeared from later settlements.

    Archaeologists found evidence of farming—including sickles, grinding stones, domesticated seeds, and, yes, weeds—in a sedentary camp that was flooded by the Sea of Galilee until the 1980s when drought and water pumping shrank the lake’s footprint. The 150,000 seeds found at the site represent 140 plant species, including wild oat, barley, and emmer wheat along with 13 weed species that are common today. The find not only illustrates humanity’s initial forays into farming, but it also provides the earliest evidence that weeds evolved alongside human ecological disturbances like farms and settlement clearings.

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    Archaeologists found wild barley seeds buried at the site.

    Mysteriously, the lessons learned from those early trials either were forgotten or were a failure. The study’s authors point out that neither sickles nor similar seeds have been found at settlements dating to just after the Sea of Galilee site, which is known as Ohalo II.

    The settlement was composed of a number of huts covered with tree branches, leaves, and grasses. Archaeologists also found a variety of flint and ground stone tools, several hearths, beads, animal remains, and an adult male gravesite. They suspect Ohalo II was occupied year round based on the remains of various migratory birds, which are known to visit the area during different times of year.

    The seeds that made up much of the settlers’ diets are surprisingly familiar. Here’s Ainit Snir and colleagues, writing in their paper published in PLoS One:

    Some of the plants are the progenitors of domesticated crop species such as emmer wheat, barley, pea, lentil, almond, fig, grape, and olive. Thus, about 11,000 years before what had been generally accepted as the onset of agriculture, people’s diets relied heavily on the same variety of plants that would eventually become domesticated.

    While Snir and coauthors think that Ohalo II’s fields were simply early trials and that plants weren’t fully domesticated until 11,000 years later, they do suspect that future discoveries could flesh out long, trial-and-error development of agriculture.

    See the full article here.

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    NOVA is the highest rated science series on television and the most watched documentary series on public television. It is also one of television’s most acclaimed series, having won every major television award, most of them many times over.

     
  • richardmitnick 5:43 pm on July 27, 2015 Permalink | Reply
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    From Symmetry: “W bosons remain left-handed” 

    Symmetry

    July 27, 2015
    Sarah Charley

    1
    LHCb. Courtesy of CERN

    A new result from the LHCb collaboration weakens previous hints at the existence of a new type of W boson.

    A measurement released today by the LHCb collaboration dumped some cold water on previous results that suggested an expanded cast of characters mediating the weak force.

    The weak force is one of the four fundamental forces, along with the electromagnetic, gravitational and strong forces. The weak force acts on quarks, fundamental building blocks of nature, through particles called W and Z bosons.

    2
    The Feynman diagram for beta decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W boson

    3
    A Feynman diagram showing the exchange of a pair of W bosons. This is one of the leading terms contributing to neutral Kaon oscillation

    Just like a pair of gloves, particles can in principle be left-handed or right-handed. The new result from LHCb presents evidence that the W bosons that mediate the weak force are all left-handed; they interact only with left-handed quarks.

    This weakens earlier hints from the Belle and BaBar experiments of the existence of right-handed W bosons.

    The LHCb experiment at the Large Hadron Collider examined the decays of a heavy and unstable particle called Lambda-b—a baryon consisting of an up quark, down quark and bottom quark.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC

    Weak decays can change a bottom quark into either a charm quark, about 1 percent of the time, or into a lighter up quark. The LHCb experiment measured how often the bottom quark in this particle transformed into an up quark, resulting in a proton, muon and neutrino in the final state.

    “We found no evidence for a new right-handed W boson,” says Marina Artuso, a Professor of Physics at Syracuse University and a scientist working on the LHCb experiment.

    If the scientists on LHCb had seen bottom quarks turning into up quarks more often than predicted, it could have meant that a new interaction with right-handed W bosons had been uncovered, Artuso says. “But our measured value agreed with our model’s value, indicating that the right-handed universe may not be there.”

    Earlier experiments by the Belle and BaBar collaborations studied transformations of bottom quarks into up quarks in two different ways: in studies of a single, specific type of transformation, and in studies that ideally included all the different ways the transformation occurs.

    If nothing were interfering with the process (like, say, a right-handed W boson), then these two types of studies would give the same value of the bottom-to-up transformation parameter. However, that wasn’t the case.

    The difference, however, was small enough that it could have come from calculations used in interpreting the result. Today’s LHCb result makes it seem like right-handed W bosons might not exist after all, at least not in a way that is revealed in these measurements.

    Michael Roney, spokesperson for the BaBar experiment, says, “This result not only provides a new, precise measurement of this important Standard Model parameter, but it also rules out one of the interesting theoretical explanations for the discrepancy… which still leaves us with this puzzle to solve.”

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 4:16 pm on July 27, 2015 Permalink | Reply
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    From Keck: “Fossil Star Clusters Reveal Their Age” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 27, 2015

    1
    Cosmic timeline showing the birth of the Universe in a Big Bang 13.7 billion years ago to the present day. Using the Keck Observatory, an international team of researchers led by Professor Forbes of Swinburne University of Technology has determined ancient star clusters, known as globular clusters, formed in two epochs – 12.5 and 11.5 billion years ago. They formed alongside galaxies, rather than prior to galaxies, as previously thought. Credit: NASA/CXC/SAO and A. Romanowsky.

    Using a new age-dating method and the W. M. Keck Observatory on Maunakea, an international team of astronomers have determined that ancient star clusters formed in two distinct epochs – the first 12.5 billion years ago and the second 11.5 billion years ago. These results are being published in Monthly Notices of the Royal Astronomical Society.

    Although the clusters are almost as old as the Universe itself, these age measurements show the star clusters – called globular clusters – are actually slightly younger than previously thought.

    “We now think that globular clusters formed alongside galaxies rather than significantly before them,” research team leader, Professor Duncan Forbes of Swinburne University of Technology said.

    The new estimates of the star cluster average ages were made possible using data obtained from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, which was carried out on Keck Observatory’s 10-meter, Keck II telescope. Observations were carried out over years using the powerful DEIMOS multi-object spectrograph fitted on Keck II, which is capable of obtaining spectra of one hundred globular clusters in a single exposure.

    Keck DEIMOS
    DEIMOS

    DEIMOS breaks the visible wavelengths of objects into spectra, which the team used to reverse-engineer the ages of the globular clusters by comparing the chemical composition of the globular clusters with the chemical composition of the Universe as it changes with time.

    “The Universe is now well known to be 13.7 billion years old,” research team member and Professor Jean Brodie said. “We determined globular clusters form on average some 1.2 and 2.2 billion years after the Big Bang.”

    “Our age measurements indicate that globular clusters managed to avoid the period, called cosmic re-ionization, in which the Universe was bathed in ultra-violet radiation which could have destroyed them” said fellow team member, Professor Aaron Romanowsky.

    “Now that we have estimated when globular clusters form, we next need to tackle the questions of where and how they formed.” Forbes said.

    The SLUGGS survey is comprised of an international team of astronomers who aim to understand the formation and evolution of galaxies and their globular cluster systems.

    Globular clusters are tightly bound clusters of around a million stars. Most large galaxies, including the Milky Way, host a system of globular clusters. Although the Universe itself, and galaxies within it, has evolved over cosmic time, globular clusters are very robust and many have survived intact for over 10 billion years.

    The team of astronomers includes researchers and PhD students from Swinburne University of Technology (Australia), University of California at Santa Cruz (USA), San Jose State University (USA).

    DEIMOS (the DEep Imaging and Multi-Object Spectrograph) boasts the largest field of view (16.7 arcmin by 5 arcmin) of any of the Keck instruments, and the largest number of pixels (64 Mpix). It is used primarily in its multi-object mode, obtaining simultaneous spectra of up to 130 galaxies or stars. Astronomers study fields of distant galaxies with DEIMOS, efficiently probing the most distant corners of the universe with high sensitivity.

    See the full article here.

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    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
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  • richardmitnick 3:55 pm on July 27, 2015 Permalink | Reply
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    From SLAC: “New ‘Molecular Movie’ Reveals Ultrafast Chemistry in Motion” 


    SLAC Lab

    June 22, 2015


    This video describes how the Linac Coherent Light Source, an X-ray free-electron laser at SLAC National Accelerator Laboratory, provided the first direct measurements of how a ring-shaped gas molecule unravels in the millionths of a billionth of a second after it is split open by light. The measurements were compiled in sequence to form the basis for computer animations showing molecular motion. (SLAC National Accelerator Laboratory)

    Scientists for the first time tracked ultrafast structural changes, captured in quadrillionths-of-a-second steps, as ring-shaped gas molecules burst open and unraveled. Ring-shaped molecules are abundant in biochemistry and also form the basis for many drug compounds. The study points the way to a wide range of real-time X-ray studies of gas-based chemical reactions that are vital to biological processes.

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    This illustration shows shape changes that occur in quadrillionths-of-a-second intervals in a ring-shaped molecule that was broken open by light. The molecular motion was measured using SLAC’s Linac Coherent Light Source X-ray laser. The colored chart shows a theoretical model of molecular changes that syncs well with the actual results. The squares in the background represent panels in an LCLS X-ray detector. (SLAC National Accelerator Laboratory)

    Researchers working at the Department of Energy’s SLAC National Accelerator Laboratory compiled the full sequence of steps in this basic ring-opening reaction into computerized animations that provide a “molecular movie” of the structural changes.

    Conducted at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the pioneering study marks an important milestone in precisely tracking how gas-phase molecules transform during chemical reactions on the scale of femtoseconds. A femtosecond is a millionth of a billionth of a second.

    “This fulfills a promise of LCLS: Before your eyes, a chemical reaction is occurring that has never been seen before in this way,” said Mike Minitti, a SLAC scientist who led the experiment in collaboration with Peter Weber at Brown University. The results are featured in the June 22 edition of Physical Review Letters.

    “LCLS is a game-changer in giving us the ability to probe this and other reactions in record-fast timescales,” Minitti said, “down to the motion of individual atoms.” The same method can be used to study more complex molecules and chemistry.

    The free-floating molecules in a gas, when studied with the uniquely bright X-rays at LCLS, can provide a very clear view of structural changes because gas molecules are less likely to be tangled up with one another or otherwise obstructed, he added. “Until now, learning anything meaningful about such rapid molecular changes in a gas using other X-ray sources was very limited, at best.”

    New Views of Chemistry in Action

    The study focused on the gas form of 1,3-cyclohexadiene (CHD), a small, ring-shaped organic molecule derived from pine oil. Ring-shaped molecules play key roles in many biological and chemical processes that are driven by the formation and breaking of chemical bonds. The experiment tracked how the ringed molecule unfurls after a bond between two of its atoms is broken, transforming into a nearly linear molecule called hexatriene.

    “There had been a long-standing question of how this molecule actually opens up,” Minitti said. “The atoms can take different paths and directions. Tracking this ultimately shows how chemical reactions are truly progressing, and will likely lead to improvements in theories and models.”

    The Making of a Molecular Movie

    In the experiment, researchers excited CHD vapor with ultrafast ultraviolet laser pulses to begin the ring-opening reaction. Then they fired LCLS X-ray laser pulses at different time intervals to measure how the molecules changed their shape.

    Researchers compiled and sorted over 100,000 strobe-like measurements of scattered X-rays. Then, they matched these measurements to computer simulations that show the most likely ways the molecule unravels in the first 200 quadrillionths of a second after it opens. The simulations, performed by team member Adam Kirrander at the University of Edinburgh, show the changing motion and position of its atoms.

    Each interval in the animations represents 25 quadrillionths of a second ­– about 1.3 trillion times faster than the typical 30-frames-per-second rate used to display TV shows.

    “It is a remarkable achievement to watch molecular motions with such incredible time resolution,” Weber said.

    A gas sample was considered ideal for this study because interference from any neighboring CHD molecules would be minimized, making it easier to identify and track the transformation of individual molecules. The LCLS X-ray pulses were like cue balls in a game of billiards, scattering off the electrons of the molecules and onto a position-sensitive detector that projected the locations of the atoms within the molecules.

    A Successful Test Case for More Complex Studies

    “This study can serve as a benchmark and springboard for larger molecules that can help us explore and understand even more complex and important chemistry,” Minitti said.

    Additional contributors included scientists at Brown and Stanford universities in the U.S. and the University of Edinburgh in the U.K. The work was supported by the DOE Office of Basic Energy Sciences.

    See the full article here.

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 11:54 am on July 27, 2015 Permalink | Reply
    Tags: , , , Planetary Nebulas   

    From ESA: “Born-again planetary nebula” 

    ESASpaceForEuropeBanner
    European Space Agency

    27/07/2015
    No Writer Credit

    1

    Beneath the vivid hues of this eye-shaped cloud, named Abell 78, a tale of stellar life and death is unfolding. At the centre of the nebula, a dying star – not unlike our Sun – which shed its outer layers on its way to oblivion has, for a brief period of time, come back to echo its past glory.

    Releasing their outer shells is the usual fate for any star with a mass of 0.8–8 times that of the Sun. Having exhausted the nuclear fuel in their cores after burning for billions of years, these stars collapse to become dense, hot white dwarf stars. Around them, the ejected material strikes the ambient gas and dust, creating beautiful clouds known as ‘planetary nebulas’. This curious name was adopted by 18th-century astronomers who discovered these ‘puffing’ stars and thought their round shape similar to that of planets.

    However, the resurgence to life seen in this image is an exceptional event for a planetary nebula. Only a handful of such born-again stars have been discovered, and here the intricate shape of the cloud’s glowing material gives away its turbulent history.

    Although nuclear burning of hydrogen and helium had ceased in the core of the dying star, causing it to collapse under its own weight and its envelope to expand into a bubble, some of the star’s outer layers became so dense that fusion of helium resumed there.

    The renewed nuclear activity triggered another, much faster wind, blowing more material away. The interplay between old and new outflows has shaped the cloud’s complex structure, including the radial filaments that can be seen streaming from the collapsing star at the centre.

    The interaction between slow and fast winds gusting in the environment of Abell 78 heated the gas to over a million degrees, making it shine brightly in X-rays. Astronomers detected this hot gas with ESA’s XMM-Newton space observatory, revealing striking similarities with another born-again planetary nebula, Abell 30.

    ESA XMM Newton
    XMM-Newton

    This three-colour image combines X-ray data collected in 2013 by XMM-Newton (blue) with optical observations obtained using two special filters that reveal the glow of oxygen (green) and helium (red). The optical data were gathered in 2014 with the Andalusian Faint Object Spectrograph and Camera at the Nordic Optical Telescope on La Palma, in the Canary Islands. A study of the X-ray emission from Abell 78 is presented in a paper by J.A. Toalá et al. 2015.

    Nordic Optical Telescope
    Nordic Opitcal Telescope Interior
    Nordic Optical telescope

    See the full article here.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 9:33 am on July 27, 2015 Permalink | Reply
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    From livescience: “Ancient Volcano Tattooed the Earth with Giant Rings” 

    Livescience

    July 24, 2015
    Elizabeth Goldbaum

    1
    Aerial image of the Pilanesberg National Park in South Africa captured by the Operational Land Imager [OLI] on Landsat 8 by NASA Earth Observatory.
    Credit: Jesse Allen

    NASA LandSat8 OLI
    OLI

    Concentric circles of rocky hills and valleys in South Africa tell the story of a billion-year-old collapsed volcano in newly released photos from NASA.

    The circular Pilanesberg caldera is located in the South African province known as North West, in Pilanesberg National Park. The caldera, or cauldron-shaped crater, features different rings of rock that make up a near perfect circle, with structures that rise about 330 to 1,640 feet (100 to 500 meters) above the surrounding landscape. The tallest point, Matlhorwe Peak, soars 5,118 feet (1,560 m) above sea level.

    Several streams typically flow through the valleys of these structures, but the Earth-watching Landsat 8 satellite captured the landscape when it was dry, according to NASA Earth Observatory.

    NASA LandSat 8
    NASA Landsat 8

    Man-made dams trap water for the many animals in the region, and Mankwe Lake, the largest body of water in the park, is located in the lowlands east of the center of the rings.

    The Pilanesberg’s story begins about 1.3 billion years ago, when only very simple organisms, like algae, roamed the Earth and volcanoes frequently spewed magma. This molten rock is created in a large pool (called a “hot spot”) just below the Earth’s crust. When there’s enough of the substance, the pressure rises and magma eventually forces its way through the crust, bursting in a shower of fiery, boiling rock, ash and gas.

    After the eruption, the ruptured crust collapses into the magma chamber, similar to how skin subsides after a pimple is popped. Magma remaining underneath the crust is propelled upward, just as pus seeps out from under the skin after a pimple bursts, and floods the landscape as lava. The lava then solidifies into volcanic rocks, which can look dark and glassy (obsidian) or grey and spongy (basalt), and can display other characteristics.

    Magma that does not make it to the surface as lava cools and hardens, clogging the cracks inside the Earth. These solidified magma formations are called dikes, and in Pilanesberg, many of the dikes are circular because of the circular cracks. As such, these formations are known as ring dikes, NASA officials said.

    This cycle occurred many times during this volcano’s active period of about 1 million years, according to NASA. Each time new cracks opened, melted magma erupted and formed different rocks. Tectonic activity, or the movement of continental plates, eventually drifted the volcano away from its hot spot, so Pilanesberg is now dormant, according to NASA Earth Observatory.

    In the millions of years since Pilanesberg stopped erupting, erosion from rain, wind and other natural processes removed the volcanic rocks and exposed the inside of the original volcano and its erosion-resistant ring dikes, which are the strangely circular features seen today.

    Ring dikes are not common features, NASA said. Only a few such structures are known in the world, including the Ossipee Mountains in New Hampshire. The Ossipee ring dike formed around 90 million years ago, during the second of three major eruptions throughout the active period of the volcano that created the structure. The original volcano was thought to be around 10,000 feet tall (3,048 m), though the region’s current highest peak is Mount Shaw, which rises 3,200 feet (975 m) above sea level.

    In the Pilanesberg caldera, a valley that resulted from a crack in the Earth’s crust (caused by tectonic activity) cuts from the southwest to the northeast of the ring dikes. Life eventually took over the region’s circular hills and valleys, morphing the barren rocks into grassy grazing grounds for elephants, buffalos, giraffes, and white and black rhinoceroses, among other creatures.

    See the full article here.

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  • richardmitnick 9:15 am on July 27, 2015 Permalink | Reply
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    From phys.org: “We will find organic materials on Asteroid Bennu, says OSIRIS-REx principal investigator” 

    physdotorg
    phys.org

    July 27, 2015
    Tomasz Nowakowski

    1
    OSIRIS-REx

    (Phys.org)—In September 2016, NASA plans to launch its first-ever asteroid sample return mission loaded with tasks that will help us better understand the composition of asteroids, their origin, and possibly even Earth’s origin. The Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) mission designed to study asteroids, which are the leftover debris from the solar system formation process, could teach us a lot about the history of the sun and planets.

    The spacecraft, equipped with scientific instruments to map the near-Earth asteroid Bennu and to detect minerals and organic molecules that could be the signs of microbial life, is slated to reach its target in 2018 and return a sample to Earth in 2023. It will bring back at least a 2.1-ounce sample to study.

    One of the instruments, the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) is designed to measure visible and near infrared light from the asteroid, to identify which chemicals are present on the space rock.

    NASA OSIRIS-REX OVIRS
    OVIRS

    The mission’s principal investigator, Dante Lauretta of the University of Arizona, Tucson, and the rest of the team are convinced that OSIRIS-REx will succeed in finding organic materials on Bennu.

    “We definitely believe we will find organic materials on Bennu and OVIRS’s job is to find and identify these organics,” Lauretta told Phys.org.

    Bennu is a carbon-rich asteroid that records the earliest history of our solar system because its composition probably has remained unchanged since it formed some four billion years ago. It could contain natural resources such as water, organics and precious metals—precursors to the origin of life. So could we even find primitive, microbial lifeforms on Bennu?

    Lauretta debunks this suggestion. He is convinced it is unlikely to find life in such a harsh space environment.

    “We are also confident that microbial life does not exist on Bennu. A body the size of Bennu has too little atmosphere and gravity to protect any known life form from the ravages of space,” Lauretta noted.

    To better identify chemicals on Bennu, the OVIRS instrument will split the light from the asteroid into its component wavelengths, similar to a prism that splits sunlight into a rainbow, but over a much broader range of wavelengths. Different chemicals express unique spectral signatures by absorbing sunlight and can be identified in the reflected spectrum.

    “In particular, we are looking to find the areas of Bennu rich in organic molecules to identify possible sample sites of high science value, but the instrument will also help us understand the general composition of Bennu,” Lauretta said. “Besides OVIRS, OSIRIS-REx has four other science instruments on board. They will all survey Bennu to determine its form, composition and make-up.”

    OTES (OSIRIS-REx Thermal Emission Spectrometer), from Arizona State University, will provide mineral and temperature information by collecting infrared spectral data from Bennu. According to Lauretta, thermal data from OTES will allow scientists to determine the mineral composition and temperature distribution of Bennu for global maps and local candidate sample-site areas.

    NASA OSIRIS REX OTES
    OTES

    Another instrument named OCAMS (OSIRIS-REx Camera Suite), built by the University of Arizona, is a suite of three cameras that will provide global image mapping and sample site imaging. It will also record the entire sampling procedure.

    “These cameras will give us the best up-close visuals of the asteroid that we have to date,” Lauretta revealed.

    OSIRIS-REx Laser Altimeter or OLA, is a scanning LIDAR (remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light), developed by the Canadian Space Agency. It will provide the mission with high-resolution topographical information about Bennu and will also help with sample site selection.

    NASA OSIRIS REX OLA
    OLA

    The fifth asteroid-exploring instrument – REXIS (Regolith X-ray Imaging Spectrometer), was built jointly by the Massachusetts Institute of Technology (MIT) and the Harvard College Observatory. REXIS will determine the elements that are present on Bennu and will complement the mineral mapping provided by OVIRS and OTES.

    The OSIRIS-REx spacecraft is now in the assembly, testing, and launch operations phase. To be fully ready for a demanding trip and scientific operations at its target asteroid, all the instruments need to be thoroughly tested after installation to ensure that they interact properly with all of the other systems on the spacecraft.

    “OTES was installed in late June and the OVIRS instrument was delivered in early July. OCAMS and REXIS will be installed in late summer and OLA will be delivered in the fall,” Lauretta said.

    After all the instruments are installed, the spacecraft will then go through system level environmental testing until next May, when it is scheduled to be shipped to Cape Canaveral, Florida. There, it will be mated to the Atlas V rocket and readied for our launch in September 2016.

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
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