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  • richardmitnick 10:04 am on May 24, 2017 Permalink | Reply
    Tags: , , , Binary star composed of two brown dwarfs discovered by microlensing, , phys.org   

    From phys.org: “Binary star composed of two brown dwarfs discovered by microlensing” 

    physdotorg
    phys.org

    May 23, 2017
    Tomasz Nowakowski

    1
    Light curve of the microlensing event OGLE-2016-BLG-1469. The upper panel shows the enlarged view of the anomaly around the peak. The two lower panels show the residual from the binary-lens models with (orbit+parallax) and without (standard) considering higher-order effects. Credit: Han et al., 2017.

    Using gravitational microlensing, astronomers have recently found a binary star composed of two brown dwarfs.

    Now, a team of astronomers led by Cheongho Han of the Chungbuk National University in Cheongju, South Korea, reports the detection of a new brown-dwarf binary system from the analysis of the microlensing event OGLE-2016-BLG-1469. The discovery is the result of a joint effort of over 50 scientists working in three microlensing research groups. The team consists of researchers from the Korea Microlensing Telescope Network (KMTNet), the Optical Gravitational Lensing Experiment (OGLE) and the Microlensing Observations in Astrophysics (MOA).

    For their observations of OGLE-2016-BLG-1469, MOA researchers employed the 1.8m telescope at the Mt. John University Observatory in New Zealand, while OGLE scientists used the 1.3m telescope located at the Las Campanas Observatory in Chile. When it comes to KMTNet, the astronomers utilized three identical 1.6m telescopes located at the Cerro Tololo Inter-American Observatory in Chile, the South African Astronomical Observatory in South Africa, and the Siding Spring Observatory in Australia.

    Mt John University Observatory 1.8m MOA telescope NZ

    1.3 meter OGLE Warsaw Telescope at the Las Campanas Observatory in Chile

    SAAO 1.9 meter Telescope, at the SAAO observation station 15Kms from the small Karoo town of Sutherland in the Northern Cape, a 4-hour drive from Cape Town.

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    AAO 1.2m UK Schmidt Telescope at Siding Spring Observatory, near Coonabarabran, New South Wales, Australia

    The newly discovered system is the third brown-dwarf binary detected with this technique. The finding was presented in a paper published May 16 on the arXiv pre-print server.

    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.

     
  • richardmitnick 7:27 am on May 23, 2017 Permalink | Reply
    Tags: , Dirac fermions, , Force-carrying bosons, , phys.org, , , Universiteit Leiden,   

    From Universiteit Leiden via phys.org: “Weyl fermions exhibit paradoxical behavior” 

    1

    Universiteit Leiden

    phys.org

    May 23, 2017
    No writer credit found

    1
    Credit: Leiden Institute of Physics

    Theoretical physicists have found Weyl fermions to exhibit paradoxical behavior in contradiction to a 30-year-old fundamental theory of electromagnetism. The discovery has possible applications in spintronics. The study has been published in Physical Review Letters.

    Physicists divide the world of elementary particles into two groups. On one side are force-carrying bosons, and on the other there are so-called fermions. The latter group comes in three different flavors. Dirac fermions are the most famous, comprising all matter. Physicists recently discovered Majorana fermions, which might form the basis of future quantum computers. Lastly, Weyl fermions exhibit weird behavior in, for example, electromagnets, which has sparked the interest of Prof. Carlo Beenakker’s theoretical physics group.

    Electromagnets

    Conventional electromagnets work on the interplay between electrical currents and magnetic fields. Inside a dynamo, a rotating magnet generates electricity, and vice versa: Moving electrical charges in a wire wrapped around a metal bar will induce a magnetic field. Paradoxically, an electric current produced within the bar in the same direction would produce a magnetic field around it, in turn generating a current in the opposite direction, and the whole system would collapse.

    Oddly enough, Beenakker and his group have found cases where this does actually happen. Following an idea from collaborator Prof. İnanç Adagideli (Sabanci University), Ph.D. student Thomas O’Brien built a computer simulation showing that materials harboring Weyl fermions actually exhibit this weird behavior. This has been observed before, but only at artificially short timescales, when the system didn’t get time to correct for the anomaly. The Leiden/Sabanci collaboration showed that in special circumstances—at temperatures close to absolute zero when materials become superconducting—the strange scenario occurs indefinitely.

    Until now, physicists considered this to be impossible due to underlying symmetries in the models used. That gives the discovery fundamental significance. “We study Weyl fermions mainly out of a fundamental interest,” says O’Brien. “Still, this research gives more freedom in the use of magnetism and materials. Perhaps the additional flexibility in a Weyl semimetal will be of use in future electronics design.”

    See the full article here.

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    Leiden University was founded in 1575 and is one of Europe’s leading international research universities. It has seven faculties in the arts, sciences and social sciences, spread over locations in Leiden and The Hague. The University has over 6,500 staff members and 26,900 students. The motto of the University is ‘Praesidium Libertatis’ – Bastion of Freedom.

     
  • richardmitnick 3:31 pm on May 22, 2017 Permalink | Reply
    Tags: phys.org, Study finds female students less likely to drop engineering program if female mentored, UMASS,   

    From UMASS: via phys.org: Women in STEM “Study finds female students less likely to drop engineering program if female mentored” 

    1

    University of Massachusetts

    phys.org

    May 22, 2017
    Bob Yirka

    1
    Credit: CC0 Public Domain

    A pair of researchers with the University of Massachusetts has found evidence that suggests women are more likely to continue to pursue a degree in engineering if they have a female mentor. Nilanjana Dasgupta, an instructor, and her Ph.D. student Tara Dennehy paired first-year female engineering majors with older mentors for a year and then looked at the impact mentoring had the decision to continue pursuing their degree as they moved into their second year. They have published their findings in Proceedings of the National Academy of Sciences.

    Far fewer women than men receive bachelor’s degrees in the STEM fields (just 13 to 33 percent), despite women comprising approximately 56 percent of all students attending college in the United States. Dasgupta and Dennehy note that the disparity is most notable in engineering. They suggest the reason that women choose to drop out or to change majors is because many such environments are unfriendly, or even hostile to female students. Quite often, female students are made to feel as if they do not belong. They note also that some efforts have been made to make such environments friendlier, but thus far, little progress has been made. They wondered if female students in such fields might benefit from having a female mentor. To find out, they enlisted the assistance of 150 people (male and female) working as engineers to serve as mentors for 150 female engineering students during their freshman year. The students met with their mentor once a month and were interviewed by the research pair three times during their first year and then again, a year later.

    The researchers found that the female students were much more likely to continue to pursue their engineering degree if they had a female mentor, but not if they had a male mentor (18 percent of them dropped out) or no mentor (11 percent dropped out). They report that all of the female students given a female mentor chose to continue with their major their second year. They also note that mentoring appeared to have a lasting impact, as most of those assigned female mentors reported plans to continue with their engineering degree into their third year.

    See the full article here .

    See also How Women Mentors Make a Difference in Engineering

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    U Mass Amherst campus

    UMass Amherst, the Commonwealth’s flagship campus, is a nationally ranked public research university offering a full range of undergraduate, graduate and professional degrees.

    As the flagship campus of America’s education state, the University of Massachusetts Amherst is the leader of the public higher education system of the Commonwealth, making a profound, transformative impact to the common good. Founded in 1863, we are the largest public research university in New England, distinguished by the excellence and breadth of our academic, research and community outreach programs. We rank 29th among the nation’s top public universities, moving up 11 spots in the past two years in the U.S. News & World Report’s annual college guide.

     
  • richardmitnick 1:16 pm on May 15, 2017 Permalink | Reply
    Tags: , , AX J1910.7+0917, AX J1910.7+0917 is the slowest X-ray pulsar study finds, , , phys.org   

    From phys.org: “AX J1910.7+0917 is the slowest X-ray pulsar, study finds” 

    physdotorg
    phys.org

    May 15, 2017
    Tomasz Nowakowski

    1
    An artist’s rendering of an X-ray pulsar. Credit: NASA

    European astronomers have found that an X-ray pulsar designated AX J1910.7+0917 has the slowest spin period among other objects in this class. The research team, led by Lara Sidoli of the National Institute for Astrophysics and Space Physics (INAF) in Milan, Italy, presented the new findings in a paper published May 4.

    X-ray pulsars (also known as accretion-powered pulsars) are sources displaying strict periodic variations in X-ray intensity, consisting of a magnetized neutron star in orbit with a normal stellar companion. In these binary systems, the X-ray emission is powered by the release of gravitational potential energy as material is accreted from a massive companion. X-ray pulsars are among the most luminous objects in the X-ray sky.

    AX J1910.7+0917 was detected by Japan’s Advanced Satellite for Cosmology and Astrophysics (ASCA) in 2001 as part of the ASCA Galactic Plane Survey (AGPS).

    JAXA ASCA ASTRO-D satellite

    It was initially classified as a relatively faint and poorly known X-ray source. Due to the fact that this source lies at a projected distance of about 12′ from the supernova remnant W49, it was the target of many observations. Pulsations from this source were discovered in 2011 during observations conducted with NASA’s Chandra X-ray Observatory.

    NASA/Chandra Telescope

    Recently, Sidoli’s team has thoroughly analyzed the available data provided by the observations of AX J1910.7+0917 with ASCA, Chandra and ESA’s X-ray Multi-Mirror Mission (XMM-Newton) spacecraft.

    ESA/XMM Newton

    The study revealed more details about this high mass X-ray pulsar.

    “Pulsations from the high mass X-ray binary AX J1910.7+0917 were discovered during Chandra observations performed in 2011 (Israel et al. 2016). We report here more details on this discovery and discuss the source nature,” the researchers wrote in the paper.

    The scientists found that the spin period of the X-ray signal is 36,200 seconds, with a pulsed fraction of 63 percent. Such a long period makes it the slowest X-ray pulsar known so far.

    “This discovery makes AX J1910.7+0917 the pulsar with the slowest spin period,” the paper reads.

    The researchers assigned this long periodicity to the rotation of the pulsar’s neutron star. They assume that a very long neutron star spin period can be explained within a quasi-spherical settling accretion model, that applies to low luminosity, wind-fed, X-ray pulsars.

    “A quasi-spherical settling accretion model (Shakura et al. 2012) is able to explain this superslow pulsation, even adopting a typical neutron star surface magnetic field of about 1012,” the authors wrote.

    However, this hypothesis cannot be confirmed until other source parameters like orbital period and the velocity of the wind outflowing from the massive donor, are measured. Moreover, the team calls for future sensitive spectroscopy observations above 10 keV, which will be needed in order to detect cyclotron resonant scattering features and obtain a direct measurement of the neutron star’s magnetic field.

    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.

     
  • richardmitnick 1:23 pm on May 13, 2017 Permalink | Reply
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    From Cambridge via phys.org: “Scientists investigate debris disk in a nearby planetary system” 

    U Cambridge bloc

    Cambridge University

    phys.org

    May 11, 2017
    Tomasz Nowakowski

    2
    ALMA band 7 (0.86 mm) continuum image of 61 Vir with natural weights and corrected by the primary beam response (FWHM∼ 1700). Credit: Marino et al., 2017.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Astronomers have recently presented new results of observations of a nearby planetary system known as 61 Virginis (or 61 Vir for short). The observations were focused on investigating the system’s debris disk, which could hold many clues to the nature of planetary formation beyond our solar system. The study is available in a paper published May 4, 2017.

    61 Vir is a G-type, 4.6-billion-year-old main-sequence star about the size of our sun, located approximately 28 light years away. The star is known to be orbited by at least three planets that are five, 18 and 23 times more massive than Earth. One of the most intriguing features of this system is a debris disk extending from 30 to at least 100 AU from the star.

    Debris disks are clouds of planetesimals and dust found in orbits around many stars. Studying such disks could improve our understanding about planet formation and the migration history of planets in planetary systems. With this aim in mind, a team of astronomers led by Sebastian Marino of the University of Cambridge in the U.K., has performed observations of 61 Vir’s debris disk using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. These observations were complemented by data from the Submillimetre Common-User Bolometer Array 2 (SCUBA2) installed in the James Clerk Maxwell Telescope (JCMT) at Mauna Kea Observatory in Hawaii.

    East Asia Observatory James Clerk Maxwell telescope, Mauna Kea, Hawaii, USA

    “In this paper, we present the first observations of 61 Vir with ALMA at 0.86 mm, obtained with the aim of studying its debris disc to reveal the location of the parent planetesimals, and place constraints on the presence of planets at large separations that can shape the mass distribution in the disc. (…) In order to obtain the best disc constraints, in our analysis we combine new ALMA band 7 observations and new data at 0.85 mm from SCUBA2 installed on JCMT, thus, incorporating information from small and large angular scale structure,” the researchers wrote in the paper.

    The new study reveals that the debris disk is larger than previously thought. Marino’s team found that it extends from 30 to at least 150 AU. Combined ALMA and SCUBA2/JMCT observations also show that at 0.86 mm the total disc emission is about 3.7 mJy and the disk has a surface density distribution of millimeter sized grains with a power law slope of approximately 0.1.

    Moreover, the researchers assume that a yet unseen fourth planet may lurk somewhere in the system between 61 Vir d at 0.5 AU and the inner edge of the disc. They argue that if the disc was stirred at 150 AU by an additional planet, that unseen alien world should have a mass of at least 10 Earth masses and should orbit its host at a distance between 10 and 20 AU.

    “We found that in order to have stirred the disc out to 150 AU, the planet must be more massive than 10 Earth masses and a semi-major axis between 10 and 20 AU if it has an eccentricity lower than 0.1. Otherwise, for higher eccentricities, it could have a lower mass and a semi-major axis between 4 and 20 AU,” the team concluded.

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 1:34 pm on May 3, 2017 Permalink | Reply
    Tags: , phys.org, Vulcanism on Earth   

    From phys.org: “Ancient meteorite impact sparked long-lived volcanic eruptions on Earth” 

    physdotorg
    phys.org

    May 3, 2017

    1
    A photomicrograph of a vesicular green shard from the Onaping Formation of the Sudbury impact basin. Credit: Paul Guyett, Trinity College Dublin.

    Meteorite impacts can produce more than craters on the Earth – they can also spark volcanic activity that shapes its surface and climate by bringing up material from depth. That is the headline finding of an international team, led by geochemists from Trinity College Dublin, who discovered that large impacts can be followed by intense, long-lived, and explosive volcanic eruptions.

    The team studied rocks filling one of the largest preserved impact structures on the planet, located in Sudbury (Ontario, Canada). The ‘bolide’ hit the Earth here 1.85 billion years ago and excavated a deep basin, which was filled with melted target rocks and, later, with jumbled mixed rocks full of tiny volcanic fragments.

    Not only are there volcanic fragments throughout the sequence of the 1.5 km-thick basin but they have a very distinctive angular shape, which the scientists explain resembles a ‘crab claw’. Such shapes form when gas bubbles expand in molten rock that then catastrophically explodes—a feature of violent eruptions involving water, and which can be seen under glaciers in Iceland, for example. In the crater, these took place for a long period of time after the impact, when the basin was flooded with sea water.

    The key finding of the research, just published in the Journal of Geophysical Research: Planets, is that the composition of the volcanic fragments changed with time. Right after the impact, volcanism is directly related to melting of the Earth’s crust. However, with time, volcanism seems to have been fed by magma coming from deeper levels within the Earth.

    Professor of Geology and Mineralogy at Trinity, Balz Kamber, said: “This is an important finding, because it means that the magma sourcing the volcanoes was changing with time. The reason for the excitement is that the effect of large impacts on the early Earth could be more serious than previously considered.”

    On the early Earth there was a relatively brief period during which ca. 150 very large impacts occurred, whereas since then, only a handful have hit the Earth.

    Professor Kamber added: “The intense bombardment of the early Earth had destructive effects on the planet’s surface but it may also have brought up material from the planet’s interior, which shaped the overall structure of the planet.”

    The findings raise interest in topical research on similar volcanism on other planetary bodies like Mercury, Venus, Mars and the Moon. There, unlike on the Earth, the lack of plate tectonics and erosion help preserve surface features, which are probed by space craft.

    The insight from Sudbury is complemental, the geologists say, because you can directly observe the rocks with your own eyes and collect loads of samples for detailed study in the lab.

    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.

     
  • richardmitnick 4:12 pm on April 28, 2017 Permalink | Reply
    Tags: Astronomers find black hole in Sagittarius constellation, phys.org,   

    From U Manchester via phys.org: “Astronomers find black hole in Sagittarius constellation” 

    U Manchester bloc

    University of Manchester

    phys.org

    April 28, 2017

    1
    Sagittarius region of milky way. Credit: Wikipedia

    An international team of astronomers led The University of Manchester have found evidence of a new ‘missing-link’ black hole in the Milky Way galaxy, hidden in the Sagittarius constellation.

    The black hole is located approximately 26,000 light years, or 7.9 Kiloparsecs (kpc), from Earth in a globular cluster called, NGC 6624. A globular cluster is a gravitationally bound swarm of millions of old stars occupying regions that are just a few light years across.

    The team, led by Dr Benetge Perera, have found evidence that the millisecond pulsar (PSR B1820-30A) – a pulsar is highly magnetized, rapidly rotating neutron star that emits a beam of electromagnetic radiation – in NGC 6624 is most likely orbiting around an intermediate-mass black hole (IMBH) located at the cluster’s centre. The mass of black hole is so big, it is the equivalent to weight of 7,500 of our suns.

    PSR B1820 30A is the closest-known pulsar to the centre of any globular cluster and it is the first pulsar to be found orbiting a black hole. The detection of IMBHs is extremely important as they can help astronomers understand the ‘missing link’ between stellar mass black holes (SMBH), the smallest kind, and supermassive black holes (SMBH), which are the largest.

    Dr Perera, from the Jodrell Bank Centre for Astrophysics in the University’s School of Physics and Astronomy, explains: “High stellar densities towards the centre of globular clusters provide a likely environment for the formation of massive black holes. The detection of IMBHs is important for understanding the missing link between the different kinds of black holes.

    “It is generally thought that they could be formed by the direct collapse of very massive primordial stars or successive mergers of stellar-mass black holes and runaway collisions in dense young star clusters.”

    The pulsar was discovered using the Lovell Telescope, based at Jodrell Bank, in 1990. Since then the team has analysed more than 25 years of observations from PSR B1820- 30A made with the telescope. In addition to Jodrell Bank, the analysis included data obtained using the Nançay Radio Telescope in France.

    U Manchester Jodrell Bank Lovell Telescope

    Nançay decametric radio telescope Nançay France

    Professor Andrew Lyne, also from the School of Physics and Astronomy, explains the importance of discovering such pulsars: “Pulsars like PSR B1820 30A act as fantastically accurate clocks and allow us to determine precisely their distance from the Earth in the same way that global positioning satellites work. The pulsar is therefore very sensitive to any motion arising from the gravity of other nearby massive objects, such as black holes, making it easier for us to detect them.”

    Dr Perera added: “We have determined the orbital parameters and the companion mass of PSR B1820-30A from the motion measured through pulsar timing. Simply put, this means our results are consistent with the pulsar being in orbit around a central intermediate-mass black hole.

    “This discovery provides important input to our understanding of how intermediate-mass black holes and the clusters themselves form and evolve.”

    See the full article here .

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    U Manchester campus

    The University of Manchester (UoM) is a public research university in the city of Manchester, England, formed in 2004 by the merger of the University of Manchester Institute of Science and Technology (renamed in 1966, est. 1956 as Manchester College of Science and Technology) which had its ultimate origins in the Mechanics’ Institute established in the city in 1824 and the Victoria University of Manchester founded by charter in 1904 after the dissolution of the federal Victoria University (which also had members in Leeds and Liverpool), but originating in Owens College, founded in Manchester in 1851. The University of Manchester is regarded as a red brick university, and was a product of the civic university movement of the late 19th century. It formed a constituent part of the federal Victoria University between 1880, when it received its royal charter, and 1903–1904, when it was dissolved.

    The University of Manchester is ranked 33rd in the world by QS World University Rankings 2015-16. In the 2015 Academic Ranking of World Universities, Manchester is ranked 41st in the world and 5th in the UK. In an employability ranking published by Emerging in 2015, where CEOs and chairmen were asked to select the top universities which they recruited from, Manchester placed 24th in the world and 5th nationally. The Global Employability University Ranking conducted by THE places Manchester at 27th world-wide and 10th in Europe, ahead of academic powerhouses such as Cornell, UPenn and LSE. It is ranked joint 56th in the world and 18th in Europe in the 2015-16 Times Higher Education World University Rankings. In the 2014 Research Excellence Framework, Manchester came fifth in terms of research power and seventeenth for grade point average quality when including specialist institutions. More students try to gain entry to the University of Manchester than to any other university in the country, with more than 55,000 applications for undergraduate courses in 2014 resulting in 6.5 applicants for every place available. According to the 2015 High Fliers Report, Manchester is the most targeted university by the largest number of leading graduate employers in the UK.

    The university owns and operates major cultural assets such as the Manchester Museum, Whitworth Art Gallery, John Rylands Library and Jodrell Bank Observatory which includes the Grade I listed Lovell Telescope.

     
  • richardmitnick 7:32 pm on April 25, 2017 Permalink | Reply
    Tags: , , , , , , phys.org   

    From Durham via phys.org: “New survey hints at exotic origin for the Cold Spot” 

    Durham U bloc

    Durham University

    phys.org

    April 25, 2017

    1
    Figure 1. The map of the cosmic microwave background (CMB) sky produced by the Planck satellite. Red represents slightly warmer regions, and blue slightly cooler regions. The Cold Spot is shown in the inset, with coordinates on the x- and y-axes, and the temperature difference in millionths of a degree in the scale at the bottom. Credit: ESA and Durham University

    ESA/Planck

    A supervoid is unlikely to explain a ‘Cold Spot’ in the cosmic microwave background, according to the results of a new survey, leaving room for exotic explanations like a collision between universes. The researchers, led by postgraduate student Ruari Mackenzie and Professor Tom Shanks in Durham University’s Centre for Extragalactic Astronomy, publish their results in the Monthly Notices of the Royal Astronomical Society.

    The cosmic microwave background (CMB), a relic of the Big Bang, covers the whole sky. At a temperature of 2.73 degrees above absolute zero (or -270.43 degrees Celsius), the CMB has some anomalies, including the Cold Spot. This feature, about 0.00015 degrees colder than its surroundings, was previously claimed to be caused by a huge void, billions of light years across, containing relatively few galaxies.

    The accelerating expansion of the universe causes voids to leave subtle redshifts on light as it passes through via the integrated Sachs-Wolfe effect. In the case of the CMB this is observed as cold imprints. It was proposed that a very large foreground void could, in part, imprint the CMB Cold Spot which has been a source of tension in models of standard cosmology.

    Previously, most searches for a supervoid connected with the Cold Spot have estimated distances to galaxies using their colours. With the expansion of the universe more distant galaxies have their light shifted to longer wavelengths, an effect known as a cosmological redshift.

    The more distant the galaxy is, the higher its observed redshift. By measuring the colours of galaxies, their redshifts, and thus their distances, can be estimated. These measurements though have a high degree of uncertainty.

    In their new work, the Durham team presented the results of a comprehensive survey of the redshifts of 7,000 galaxies, harvested 300 at a time using a spectrograph deployed on the Anglo-Australian Telescope.


    AAO Anglo Australian Telescope near Siding Spring, New South Wales, Australia

    From this higher fidelity dataset, Mackenzie and Shanks see no evidence of a supervoid capable of explaining the Cold Spot within the standard theory.

    2
    Figure 2. The 3-D galaxy distribution in the foreground of the CMB Cold Spot, where each point is a cluster of galaxies. The galaxy distribution in the Cold Spot (black points, at right) is compared to the same in an area with no background Cold Spot (red points, at left). The number and size of low galaxy density regions in both areas are similar, making it hard to explain the existence of the CMB Cold Spot by the presence of ‘voids’. Credit: Durham University

    The researchers instead found that the Cold Spot region, before now thought to be underpopulated with galaxies, is split into smaller voids, surrounded by clusters of galaxies. This ‘soap bubble’ structure is much like the rest of the universe, illustrated in Figure 2 by the visual similarity between the galaxy distributions in the Cold Spot area and a control field elsewhere.

    Mackenzie commented: “The voids we have detected cannot explain the Cold Spot under standard cosmology. There is the possibility that some non-standard model could be proposed to link the two in the future but our data place powerful constraints on any attempt to do that.”

    If there really is no supervoid that can explain the Cold Spot, simulations of the standard model of the universe give odds of 1 in 50 that the Cold Spot arose by chance.

    Shanks added: “This means we can’t entirely rule out that the Spot is caused by an unlikely fluctuation explained by the standard model. But if that isn’t the answer, then there are more exotic explanations.

    ‘Perhaps the most exciting of these is that the Cold Spot was caused by a collision between our universe and another bubble universe. If further, more detailed, analysis of CMB data proves this to be the case then the Cold Spot might be taken as the first evidence for the multiverse – and billions of other universes may exist like our own.”

    For the moment, all that can be said is that the lack of a supervoid to explain the Cold Spot has tilted the balance towards these more unusual explanations, ideas that will need to be further tested by more detailed observations of the CMB.

    See the full article here .

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    Durham U campus

    Durham University is distinctive – a residential collegiate university with long traditions and modern values. We seek the highest distinction in research and scholarship and are committed to excellence in all aspects of education and transmission of knowledge. Our research and scholarship affect every continent. We are proud to be an international scholarly community which reflects the ambitions of cultures from around the world. We promote individual participation, providing a rounded education in which students, staff and alumni gain both the academic and the personal skills required to flourish.

     
  • richardmitnick 3:37 pm on April 25, 2017 Permalink | Reply
    Tags: Astronomers detect dozens of new quasars and galaxies, , , , , NOAJ, phys.org   

    From NAOJ via phys.org: “Astronomers detect dozens of new quasars and galaxies” 

    NAOJ

    NAOJ

    phys.org

    April 25, 2017
    Tomasz Nowakowski

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    Reduced spectra of the first set of eight quasars and possible quasars discovered in this work, displayed in decreasing order of redshift. The object name and the estimated redshift are indicated at the top left corner of each panel. The blue dotted lines mark the expected positions of the Lyα and N V λ1240 emission lines, given the redshifts. The spectra were smoothed using inverse-variance weighted means over 3 – 9 pixels (depending on the S/N), for display purposes. The bottom panel displays a sky spectrum, as a guide to the expected noise. Credit: Matsuoka et al., 2017.

    A team of astronomers led by Yoshiki Matsuoka of the National Astronomical Observatory of Japan (NAOJ) has detected a treasure trove of new high-redshift quasars (or quasi-stellar objects) and luminous galaxies. The newly found objects could be very important for our understanding of the early universe. The findings were presented Apr. 19 in a paper published on arXiv.org.

    High-redshift quasars and galaxies (at redshift higher than 5.0) are useful probes of the early universe in many respects. They offer essential clues on the evolution of the intergalactic medium, quasar evolution, early supermassive black hole growth, as well as evolution of galaxies through cosmic times. Generally speaking, they enable scientists to study the universe when it looked much different than it does today.

    Recently, Matsuoka’s team has presented the results from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which uses multi-band photometry data provided by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) survey.

    NAOJ Subaru Hyper Suprime Camera

    HSC is a wide-field camera installed on the Subaru 8.2 m telescope located at the summit of Maunakea, Hawaii and operated by NAOJ.

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    The researchers selected nearly 50 photometric candidates from the HSC-SSP source catalog and then observed them with spectrographs on the Subaru Telescope and the Gran Telescopio Canarias (GTC), located on the island on the Canary Island of La Palma, Spain.

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain

    The observations resulted in the identification of 24 new quasars and eight new luminous galaxies at redshift between 5.7 and 6.8.

    “We took optical spectra of 48 candidates with GTC/OSIRIS and Subaru/FOCAS, and newly discovered 24 quasars and 8 luminous galaxies at 5.7 < z ≤ 6.8," the paper reads.

    3
    GTC/OSIRIS

    4
    Subaru/FOCAS

    According to the study, the newly detected quasars have lower luminosity than most of the previously known high-redshift quasi-stellar objects, in contrast to the new galaxies, which have extremely high luminosity when compared to other galaxies found at similar redshift.

    The quasar with the highest redshift (6.8) described in the paper received designation J1429 − 0104, while the one with the lowest redshift (5.92) was named J0903 + 0211. Among the new galaxies, J1628 + 4312 was found at the highest redshift (6.03) and J2237 − 0006 at the lowest (5.77). J2237 − 0006 is also the most luminous newly found galaxy.

    Meanwhile, the researchers revealed that the SHELLQs project continues, and more new quasars are being discovered, which will be reported in forthcoming papers.

    “Further survey observations and follow-up studies of the identified objects, including the construction of the quasar luminosity function at z ∼ 6, are ongoing,” they wrote in the paper.

    The authors also noted that they plan to conduct follow-up observations of the newly discovered quasars and galaxies at various wavelengths from sub-millimeter/radio to X-ray. Several of these objects have already been observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, near-infrared spectrographs on the Gemini telescope, located in Hawaii and the Very Large Telescope (VLT), also in Chile.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Gemini/North telescope at Mauna Kea, Hawaii, USA

    ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    See the full article here .

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    The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

    NAOJ Subaru Telescope

    NAOJ Subaru Telescope interior
    Subaru

    ALMA Array
    ALMA

    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    Okayama Astrophysical Observatory

    The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

     
  • richardmitnick 9:47 am on April 24, 2017 Permalink | Reply
    Tags: , Lithium batteries, phys.org   

    From Columbia via phys.org: “Freezing lithium batteries may make them safer and bendable” 

    Columbia U bloc

    Columbia University

    phys.org

    [THIS IS IMPORTANT AS WE SEE GREATER USE OF LITHIUM BATTERIES]

    April 24, 2017

    1
    Schematic of vertically aligned and connected ceramic channels for enhancing ionic conduction. In the left figure, ceramic particles are randomly dispersed in the polymer matrix, where ion transport is blocked by the polymer matrix with a low conductivity. In the right one, vertically aligned and connected structure facilitates ion transport, which can be realized by the ice-templating method. Credit: Yuan Yang/Columbia Engineering.

    Yuan Yang, assistant professor of materials science and engineering at Columbia Engineering, has developed a new method that could lead to lithium batteries that are safer, have longer battery life, and are bendable, providing new possibilities such as flexible smartphones. His new technique uses ice-templating to control the structure of the solid electrolyte for lithium batteries that are used in portable electronics, electric vehicles, and grid-level energy storage. The study is published online April 24 in Nano Letters.

    Liquid electrolyte is currently used in commercial lithium batteries, and, as everyone is now aware, it is highly flammable, causing safety issues with some laptops and other electronic devices. Yang’s team explored the idea of using solid electrolyte as a substitute for the liquid electrolyte to make all-solid-state lithium batteries. They were interested in using ice-templating to fabricate vertically aligned structures of ceramic solid electrolytes, which provide fast lithium ion pathways and are highly conductive. They cooled the aqueous solution with ceramic particles from the bottom and then let ice grow and push away and concentrate the ceramic particles. They then applied a vacuum to transition the solid ice to a gas, leaving a vertically aligned structure. Finally, they combined this ceramic structure with polymer to provide mechanical support and flexibility to the electrolyte.

    “In portable electronic devices, as well as electric vehicles, flexible all-solid-state lithium batteries not only solve the safety issues, but they may also increase battery energy density for transportation and storage. And they show great promise in creating bendable devices,” says Yang, whose research group is focused on electrochemical energy storage and conversion and thermal energy management.

    Researchers in earlier studies used either randomly dispersed ceramic particles in polymer electrolyte or fiber-like ceramic electrolytes that are not vertically aligned. “We thought that if we combined the vertically aligned structure of the ceramic electrolyte with the polymer electrolyte, we would be able to provide a fast highway for lithium ions and thus enhance the conductivity,” says Haowei Zhai, Yang’s PhD student and the paper’s lead author. “We believe this is the first time anyone has used the ice-templating method to make flexible solid electrolyte, which is nonflammable and nontoxic, in lithium batteries. This opens a new approach to optimize ion conduction for next-generation rechargeable batteries.”

    In addition, the researchers say, this technique could in principle improve the energy density of batteries: By using the solid electrolyte, the lithium battery’s negative electrode, currently a graphite layer, could be replaced by lithium metal, and this could improve the battery’s specific energy by 60% to 70%. Yang and Zhai plan next to work on optimizing the qualities of the combined electrolyte and assembling the flexible solid electrolyte together with battery electrodes to construct a prototype of a full lithium battery.

    “This is a clever idea,” says Hailiang Wang, assistant professor of chemistry at Yale University. “The rationally designed structure really helps enhance the performance of composite electrolyte. I think that this is a promising approach.”

    3

    See the full article here .

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    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
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