Tagged: phys.org Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 4:56 pm on July 19, 2021 Permalink | Reply
    Tags: "Cosmic rays help supernovae explosions pack a bigger punch", , , , phys.org, ,   

    From Royal Astronomical Society (UK) via phys.org : “Cosmic rays help supernovae explosions pack a bigger punch” 

    From Royal Astronomical Society (UK)

    via

    phys.org

    7.19.21

    Media contacts

    Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243
    nam-press@ras.ac.uk

    Dr Morgan Hollis
    Royal Astronomical Society
    Mob: +44 (0)7802 877 700
    nam-press@ras.ac.uk

    Dr Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)7802 877 699
    nam-press@ras.ac.uk

    Vittoria D’Alessio
    PR and Media Manager
    University of Bath
    Tel: +44 (0)1225 383 135
    vda26@bath.ac.uk

    Science contacts

    Francisco Rodríguez Montero
    University of Oxford
    francisco.rodriguezmontero@physics.ox.ac.uk

    1
    False colour image of a supernova simulation showing hot and cold patches of gas (white/green) in the bubble and the filamentary structure of cosmic rays (blue) around the shell of the supernova remnant. Credit: F. Rodríguez Montero.

    2
    Composite X-ray and optical image of the remnant of Kepler’s supernova. The red, green and blue colours show low, intermediate and high energy X-rays observed with NASA’s Chandra X-ray Observatory, and the star field is from the Digitized Sky Survey. Credit: M. Burkey et al. National Aeronautics Space Agency (US) / Chandra X-ray Center (US) / NCSU / JPL-Caltech (US) /

    The final stage of cataclysmic explosions of dying massive stars, called supernovae, could pack an up to six times bigger punch on the surrounding interstellar gas with the help of cosmic rays, according to a new study led by researchers at the University of Oxford. The work will be presented by Ph.D. student Francisco Rodríguez Montero today (19 July) at the virtual National Astronomy Meeting (NAM 2021).

    When supernovae explode, they emit light and billions of particles into space. While the light can freely reach us, particles become trapped in spiral loops by magnetic shockwaves generated during the explosions. Crossing back and forth through shock fronts, these particles are accelerated almost to the speed of light and, on escaping the supernovae, are thought to be the source of the mysterious form of radiation known as cosmic rays.

    Due to their immense speed, cosmic rays experience strong relativistic effects, effectively losing less energy than regular matter and allowing them to travel great distances through a galaxy. Along the way, they affect the energy and structure of interstellar gas in their path and may play a crucial role in shutting down the formation of new stars in dense pockets of gas. However, to date, the influence of cosmic rays in galaxy evolution has not been well understood.

    In the first high-resolution numerical study of its kind, the team ran simulations of the evolution of the shockwaves emanating from supernovae explosions over several million years. They found that cosmic rays can play a critical role in the final stages of a supernova’s evolution and its ability to inject energy into the galactic gas that surrounds it.

    Rodríguez Montero explains that “initially, the addition of cosmic rays does not appear to change how the explosion evolves. Nevertheless, when the supernova reaches the stage in which it cannot gain more momentum from the conversion of the supernova’s thermal energy to kinetic energy, we found that cosmic rays can give an extra push to the gas, allowing for the final momentum imparted to be up to 4-6 times higher than previously predicted.”

    The results suggest that gas outflows driven from the interstellar medium into the surrounding tenuous gas, or circumgalactic medium, will be dramatically more massive than previously estimated.

    Contrary to state-of-the-art theoretical arguments, the simulations also suggest that the extra push provided by cosmic rays is more significant when massive stars explode in low-density environments. This could facilitate the creation of super-bubbles powered by successive generations of supernovae, sweeping gas from the interstellar medium and venting it out of galactic discs.

    Rodríguez Montero adds that their “results are a first look at the extraordinary new insights that cosmic rays will provide to our understanding of the complex nature of galaxy formation.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The

    The Royal Astronomical Society is a learned society and charity that encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. Its headquarters are in Burlington House, on Piccadilly in London. The society has over 4,000 members (“Fellows”), most of them professional researchers or postgraduate students. Around a quarter of Fellows live outside the UK.

    The society holds monthly scientific meetings in London, and the annual National Astronomy Meeting at varying locations in the British Isles. The Royal Astronomical Society publishes the scientific journals MNRAS and Geophysical Journal International, along with the trade magazine Astronomy & Geophysics.

    The Royal Astronomical Society maintains an astronomy research library, engages in public outreach and advises the UK government on astronomy education. The society recognises achievement in Astronomy and Geophysics by issuing annual awards and prizes, with its highest award being the Gold Medal of the Royal Astronomical Society. The RAS is the UK adhering organisation to the International Astronomical Union and a member of the UK Science Council.

    The society was founded in 1820 as the Astronomical Society of London to support astronomical research. At that time, most members were ‘gentleman astronomers’ rather than professionals. It became the Royal Astronomical Society in 1831 on receiving a Royal Charter from William IV. A Supplemental Charter in 1915 opened up the fellowship to women.

    Associated groups

    The RAS sponsors topical groups, many of them in interdisciplinary areas where the group is jointly sponsored by another learned society or professional body:

    The Astrobiology Society of Britain (with the NASA Astrobiology Institute)
    The Astroparticle Physics Group (with the Institute of Physics)
    The Astrophysical Chemistry Group (with the Royal Society of Chemistry)
    The British Geophysical Association (with the Geological Society of London)
    The Magnetosphere Ionosphere and Solar-Terrestrial group (generally known by the acronym MIST)
    The UK Planetary Forum
    The UK Solar Physics group

     
  • richardmitnick 3:22 pm on July 18, 2021 Permalink | Reply
    Tags: "Scientists get to the bottom of deep Pacific ventilation", , How and where does this old water eventually return to the surface? Two theories described., Ocean Biogeochemistry, phys.org, The deep North Pacific is a vast reservoir of remineralized nutrients and respired carbon that have accumulated over centuries., The deep Pacific plays a key role in the earth's climate system., The scientists were able to quantify in detail the pathways and timescales with which the shadow zone exchanges water with the surface ocean., , UNSW Science's School of Mathematics & Statistics, What are the pathways of the ocean circulation that supply newly ventilated surface water to the deep Pacific?   

    From University of New South Wales (AU) via phys.org : “Scientists get to the bottom of deep Pacific ventilation” 

    U NSW bloc

    From University of New South Wales (AU)

    via

    phys.org

    July 16, 2021

    1
    Credit: CC0 Public Domain.

    Recent findings, with important implications for ocean biogeochemistry and climate science, have been published by Nature Communications in a paper by Associate Professor Mark Holzer from UNSW Science’s School of Mathematics & Statistics, with co-authors Tim DeVries (University of California-Santa Barbara (US)) and Casimir de Lavergne (LOCEAN: Laboratory of Oceanography and Climatology |[GIS Climat Environnement Société] (FR) (CNRS) (CEA)).

    “The deep North Pacific is a vast reservoir of remineralized nutrients and respired carbon that have accumulated over centuries,” says Holzer. “When these deep waters are returned to the surface, their nutrients support biological production and their dissolved CO2 can be released into the atmosphere. As such, the deep Pacific plays a key role in the earth’s climate system.”

    But what are the pathways of the ocean circulation that supply newly ventilated surface water to the deep Pacific? And how and where does this old water eventually return to the surface? To date, there were two competing theories for the role that the overturning circulation plays in this.

    One theory—the ‘standard conveyor’—envisions broad overturning with Antarctic Bottom Water upwelling to around 1.5 km depth before flowing back south to the Southern Ocean. The other theory—the ‘shadowed conveyor’—argues that the overturning is compressed to lie below about 2.5 km with a largely stagnant “shadow zone” above it.

    “Our work reconciles these two theories: the shadowed conveyor correctly captures vertically compressed overturning beneath a shadow zone, while the standard view must be broadly interpreted in terms of water paths diffusing through the shadow zone. Because the shadow zone is largely shielded from the overturning circulation the question becomes how exactly does water get into and out of it,” Holzer says.

    Using novel mathematical analyses applied to a state-of-the-art ocean circulation model that optimally fits the circulation to observed tracer distributions and surface forcings, the authors were able to quantify in detail the pathways and timescales with which the shadow zone exchanges water with the surface ocean.

    “Our analyses allowed us to come up with a new schematic of the large-scale deep circulation in the Pacific. We find that diffusive transport both along and across density surfaces plays a leading role in ventilating the shadow zone.”

    Contrary to the widely held view that Pacific deep waters exclusively follow density surfaces to upwell in the Southern Ocean, the authors found that only about half of the water in the shadow zone follows this route, with the other half returning to the surface in low latitudes and in the subarctic Pacific, helping to explain the high biological production there.

    The scientists say this new understanding of the deep Pacific circulation and transport pathways will help interpret observed tracer distributions and biogeochemical processes.

    “An exciting direction for future research is to understand how the shadow zone, already low in oxygen and sensitive to increased oxygen demand, shapes the response of the ocean’s biological pump to climate change,” Holzer says.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U NSW Campus

    The University of New South Wales is an Australian public university with its largest campus in the Sydney suburb of Kensington.

    Established in 1949, UNSW is a research university, ranked 44th in the world in the 2021 QS World University Rankings and 67th in the world in the 2021 Times Higher Education World University Rankings. UNSW is one of the founding members of the Group of Eight, a coalition of Australian research-intensive universities, and of Universitas 21, a global network of research universities. It has international exchange and research partnerships with over 200 universities around the world.

    According to the 2021 QS World University Rankings by Subject, UNSW is ranked top 20 in the world for Law, Accounting and Finance, and 1st in Australia for Mathematics, Engineering and Technology. UNSW also leads Australia in Medicine, where the median ATAR (Australian university entrance examination results) of its Medical School students is higher than any other Australian medical school. UNSW enrolls the highest number of Australia’s top 500 high school students academically, and produces more millionaire graduates than any other Australian university.

    The university comprises seven faculties, through which it offers bachelor’s, master’s and doctoral degrees. The main campus is in the Sydney suburb of Kensington, 7 kilometres (4.3 mi) from the Sydney CBD. The creative arts faculty, UNSW Art & Design, is located in Paddington, and subcampuses are located in the Sydney CBD as well as several other suburbs, including Randwick and Coogee. Research stations are located throughout the state of New South Wales.

    The university’s second largest campus, known as UNSW Canberra at ADFA (formerly known as UNSW at ADFA), is situated in Canberra, in the Australian Capital Territory (ACT). ADFA is the military academy of the Australian Defense Force, and UNSW Canberra is the only national academic institution with a defense focus.

    Research centres

    The university has a number of purpose-built research facilities, including:

    UNSW Lowy Cancer Research Centre is Australia’s first facility bringing together researchers in childhood and adult cancers, as well as one of the country’s largest cancer-research facilities, housing up to 400 researchers.
    The Mark Wainwright Analytical Centre is a centre for the faculties of science, medicine, and engineering. It is used to study the structure and composition of biological, chemical, and physical materials.
    UNSW Canberra Cyber is a cyber-security research and teaching centre.
    The Sino-Australian Research Centre for Coastal Management (SARCCM) has a multidisciplinary focus, and works collaboratively with the Ocean University of China [中國海洋大學](CN) in coastal management research.

     
  • richardmitnick 9:50 pm on July 12, 2021 Permalink | Reply
    Tags: "Watching the Milky Way's supermassive black hole feed", , , phys.org,   

    From Harvard-Smithsonian Center for Astrophysics (US) via phys.org : “Watching the Milky Way’s supermassive black hole feed” 

    From Harvard-Smithsonian Center for Astrophysics (US)

    via

    phys.org

    1
    A three-color image of the central regions of the Milky Way showing the location of Sagittarius A*, the galactic center’s supermassive blackhole; X-ray in blue, optical in yellow, and infrared in red. Astronomers have obtained simultaneous mulit-band observations of a bright flare from SgrA* and modeled the mult-band radiation to estimate properties of the accretion around the black hole. Credit:D. Wang X-ray/ NASA/CXC/UMass/ et al.; Optical: D.Wang et al./ NASA/ESA/STScI/.; IR: S.Stolovy NASA/JPL-Caltech/SSC/

    The supermassive black hole at the center of our Milky Way galaxy, Sagittarius A*, is by far the closest such object to us, about 27,000 light-years away. Although it is not nearly so active or luminous as other galactic nuclei with supermassive black holes, its relative proximity makes it appear much brighter to us than other similar sources and provides astronomers with a unique opportunity to probe what happens when gas clouds or other objects get close to the “edge” of a black hole.

    Sgr A* has been monitored at radio wavelengths since its discovery in the 1950’s; variability was first reported in the radio in 1984. Astronomers model that on average Sgr A* is accreting material at a few hundredths of an Earth-mass per year, a relatively very low rate. Subsequent infrared, submillimeter, and X-ray observations confirmed this variability but also discovered that the object often flares, with the brightness thereby increasing by as much as a factor of one hundred in X-rays. Most of the steady emission is thought to be produced by electrons spiraling at close to the speed of light (called relativistic motion) around magnetic fields in a small region only about an astronomical unit in radius around the source, but there is no agreement on the mechanism(s) powering the flares.

    CfA astronomers Giovanni Fazio, Mark Gurwell, Joe Hora, Howard Smith, and Steve Willner were members of a large consortium that in July 2019 obtained simultaneous near infrared observations with the IRAC camera on Spitzer, with the GRAVITY interferometer at the European Southern Observatory, and with NASA’s Chandra and NuStar X-ray observatories (scheduled simultaneous observations with the Submillimeter Array were prevented by the Mauna Kea closure). SgrA* serendipitously underwent a major flaring event during these observations, enabling theoreticians for the first time to model a flare in considerable detail.

    Relativistic electrons moving in magnetic fields emit photons by a process known as synchrotron radiation (the most conventional scenario) but there is also a second process possible in which photons (produced either by synchrotron emission or by other sources like dust emission) are scattered off the electrons and thereby acquire additional energy, becoming X-ray photons. Modeling which combination of effects was operative in the small region around SgrA* during the flaring event offers insights into the densities of the gas, the fields, and the origin of the flare’s intensity, timing, and shape. The scientists considered a variety of possibilities and concluded that the most probable scenario is the one in which the infrared flare was produced by the first process but with the X-ray flare produced by the second process. This conclusion has several implications for the activity around this supermassive black hole, including that the electron densities and magnetic fields are comparable in magnitude to those under average conditions but that sustained particle acceleration is required to maintain the observed flare. Although the models successfully match many aspects of the flare emission, the measurements are not able to constrain the detailed physics behind the particle acceleration; these are left to future research.

    Science paper:
    Astronomy & Astrophysics

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The Harvard-Smithsonian Center for Astrophysics (US) combines the resources and research facilities of the Harvard College Observatory(US) and the Smithsonian Astrophysical Observatory(US) under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory(US) is a bureau of the Smithsonian Institution(US), founded in 1890. The Harvard College Observatory, founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University(US), and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

    Founded in 1973 and headquartered in Cambridge, Massachusetts, the CfA leads a broad program of research in astronomy, astrophysics, Earth and space sciences, as well as science education. The CfA either leads or participates in the development and operations of more than fifteen ground- and space-based astronomical research observatories across the electromagnetic spectrum, including the forthcoming Giant Magellan Telescope(CL) and the Chandra X-ray Observatory(US), one of NASA’s Great Observatories.

    Hosting more than 850 scientists, engineers, and support staff, the CfA is among the largest astronomical research institutes in the world. Its projects have included Nobel Prize-winning advances in cosmology and high energy astrophysics, the discovery of many exoplanets, and the first image of a black hole. The CfA also serves a major role in the global astrophysics research community: the CfA’s Astrophysics Data System(ADS)(US), for example, has been universally adopted as the world’s online database of astronomy and physics papers. Known for most of its history as the “Harvard-Smithsonian Center for Astrophysics”, the CfA rebranded in 2018 to its current name in an effort to reflect its unique status as a joint collaboration between Harvard University and the Smithsonian Institution. The CfA’s current Director (since 2004) is Charles R. Alcock, who succeeds Irwin I. Shapiro (Director from 1982 to 2004) and George B. Field (Director from 1973 to 1982).

    The Center for Astrophysics | Harvard & Smithsonian is not formally an independent legal organization, but rather an institutional entity operated under a Memorandum of Understanding between Harvard University and the Smithsonian Institution. This collaboration was formalized on July 1, 1973, with the goal of coordinating the related research activities of the Harvard College Observatory (HCO) and the Smithsonian Astrophysical Observatory (SAO) under the leadership of a single Director, and housed within the same complex of buildings on the Harvard campus in Cambridge, Massachusetts. The CfA’s history is therefore also that of the two fully independent organizations that comprise it. With a combined lifetime of more than 300 years, HCO and SAO have been host to major milestones in astronomical history that predate the CfA’s founding.

    History of the Smithsonian Astrophysical Observatory (SAO)

    Samuel Pierpont Langley, the third Secretary of the Smithsonian, founded the Smithsonian Astrophysical Observatory on the south yard of the Smithsonian Castle (on the U.S. National Mall) on March 1,1890. The Astrophysical Observatory’s initial, primary purpose was to “record the amount and character of the Sun’s heat”. Charles Greeley Abbot was named SAO’s first director, and the observatory operated solar telescopes to take daily measurements of the Sun’s intensity in different regions of the optical electromagnetic spectrum. In doing so, the observatory enabled Abbot to make critical refinements to the Solar constant, as well as to serendipitously discover Solar variability. It is likely that SAO’s early history as a solar observatory was part of the inspiration behind the Smithsonian’s “sunburst” logo, designed in 1965 by Crimilda Pontes.

    In 1955, the scientific headquarters of SAO moved from Washington, D.C. to Cambridge, Massachusetts to affiliate with the Harvard College Observatory (HCO). Fred Lawrence Whipple, then the chairman of the Harvard Astronomy Department, was named the new director of SAO. The collaborative relationship between SAO and HCO therefore predates the official creation of the CfA by 18 years. SAO’s move to Harvard’s campus also resulted in a rapid expansion of its research program. Following the launch of Sputnik (the world’s first human-made satellite) in 1957, SAO accepted a national challenge to create a worldwide satellite-tracking network, collaborating with the United States Air Force on Project Space Track.

    With the creation of National Aeronautics and Space Administration(US) the following year and throughout the space race, SAO led major efforts in the development of orbiting observatories and large ground-based telescopes, laboratory and theoretical astrophysics, as well as the application of computers to astrophysical problems.

    History of Harvard College Observatory (HCO)

    Partly in response to renewed public interest in astronomy following the 1835 return of Halley’s Comet, the Harvard College Observatory was founded in 1839, when the Harvard Corporation appointed William Cranch Bond as an “Astronomical Observer to the University”. For its first four years of operation, the observatory was situated at the Dana-Palmer House (where Bond also resided) near Harvard Yard, and consisted of little more than three small telescopes and an astronomical clock. In his 1840 book recounting the history of the college, then Harvard President Josiah Quincy III noted that “…there is wanted a reflecting telescope equatorially mounted…”. This telescope, the 15-inch “Great Refractor”, opened seven years later (in 1847) at the top of Observatory Hill in Cambridge (where it still exists today, housed in the oldest of the CfA’s complex of buildings). The telescope was the largest in the United States from 1847 until 1867. William Bond and pioneer photographer John Adams Whipple used the Great Refractor to produce the first clear Daguerrotypes of the Moon (winning them an award at the 1851 Great Exhibition in London). Bond and his son, George Phillips Bond (the second Director of HCO), used it to discover Saturn’s 8th moon, Hyperion (which was also independently discovered by William Lassell).

    Under the directorship of Edward Charles Pickering from 1877 to 1919, the observatory became the world’s major producer of stellar spectra and magnitudes, established an observing station in Peru, and applied mass-production methods to the analysis of data. It was during this time that HCO became host to a series of major discoveries in astronomical history, powered by the Observatory’s so-called “Computers” (women hired by Pickering as skilled workers to process astronomical data). These “Computers” included Williamina Fleming; Annie Jump Cannon; Henrietta Swan Leavitt; Florence Cushman; and Antonia Maury, all widely recognized today as major figures in scientific history. Henrietta Swan Leavitt, for example, discovered the so-called period-luminosity relation for Classical Cepheid variable stars, establishing the first major “standard candle” with which to measure the distance to galaxies. Now called “Leavitt’s Law”, the discovery is regarded as one of the most foundational and important in the history of astronomy; astronomers like Edwin Hubble, for example, would later use Leavitt’s Law to establish that the Universe is expanding, the primary piece of evidence for the Big Bang model.

    Upon Pickering’s retirement in 1921, the Directorship of HCO fell to Harlow Shapley (a major participant in the so-called “Great Debate” of 1920). This era of the observatory was made famous by the work of Cecelia Payne-Gaposchkin, who became the first woman to earn a Ph.D. in astronomy from Radcliffe College (a short walk from the Observatory). Payne-Gapochkin’s 1925 thesis proposed that stars were composed primarily of hydrogen and helium, an idea thought ridiculous at the time. Between Shapley’s tenure and the formation of the CfA, the observatory was directed by Donald H. Menzel and then Leo Goldberg, both of whom maintained widely recognized programs in solar and stellar astrophysics. Menzel played a major role in encouraging the Smithsonian Astrophysical Observatory to move to Cambridge and collaborate more closely with HCO.

    Joint history as the Center for Astrophysics (CfA)

    The collaborative foundation for what would ultimately give rise to the Center for Astrophysics began with SAO’s move to Cambridge in 1955. Fred Whipple, who was already chair of the Harvard Astronomy Department (housed within HCO since 1931), was named SAO’s new director at the start of this new era; an early test of the model for a unified Directorship across HCO and SAO. The following 18 years would see the two independent entities merge ever closer together, operating effectively (but informally) as one large research center.

    This joint relationship was formalized as the new Harvard–Smithsonian Center for Astrophysics on July 1, 1973. George B. Field, then affiliated with UC Berkeley(US), was appointed as its first Director. That same year, a new astronomical journal, the CfA Preprint Series was created, and a CfA/SAO instrument flying aboard Skylab discovered coronal holes on the Sun. The founding of the CfA also coincided with the birth of X-ray astronomy as a new, major field that was largely dominated by CfA scientists in its early years. Riccardo Giacconi, regarded as the “father of X-ray astronomy”, founded the High Energy Astrophysics Division within the new CfA by moving most of his research group (then at American Sciences and Engineering) to SAO in 1973. That group would later go on to launch the Einstein Observatory (the first imaging X-ray telescope) in 1976, and ultimately lead the proposals and development of what would become the Chandra X-ray Observatory. Chandra, the second of NASA’s Great Observatories and still the most powerful X-ray telescope in history, continues operations today as part of the CfA’s Chandra X-ray Center. Giacconi would later win the 2002 Nobel Prize in Physics for his foundational work in X-ray astronomy.

    Shortly after the launch of the Einstein Observatory, the CfA’s Steven Weinberg won the 1979 Nobel Prize in Physics for his work on electroweak unification. The following decade saw the start of the landmark CfA Redshift Survey (the first attempt to map the large scale structure of the Universe), as well as the release of the Field Report, a highly influential Astronomy & Astrophysics Decadal Survey chaired by the outgoing CfA Director George Field. He would be replaced in 1982 by Irwin Shapiro, who during his tenure as Director (1982 to 2004) oversaw the expansion of the CfA’s observing facilities around the world.

    CfA-led discoveries throughout this period include canonical work on Supernova 1987A, the “CfA2 Great Wall” (then the largest known coherent structure in the Universe), the best-yet evidence for supermassive black holes, and the first convincing evidence for an extrasolar planet.

    The 1990s also saw the CfA unwittingly play a major role in the history of computer science and the internet: in 1990, SAO developed SAOImage, one of the world’s first X11-based applications made publicly available (its successor, DS9, remains the most widely used astronomical FITS image viewer worldwide). During this time, scientists at the CfA also began work on what would become the Astrophysics Data System (ADS), one of the world’s first online databases of research papers. By 1993, the ADS was running the first routine transatlantic queries between databases, a foundational aspect of the internet today.

    The CfA Today

    Research at the CfA

    Charles Alcock, known for a number of major works related to massive compact halo objects, was named the third director of the CfA in 2004. Today Alcock overseas one of the largest and most productive astronomical institutes in the world, with more than 850 staff and an annual budget in excess of $100M. The Harvard Department of Astronomy, housed within the CfA, maintains a continual complement of approximately 60 Ph.D. students, more than 100 postdoctoral researchers, and roughly 25 undergraduate majors in astronomy and astrophysics from Harvard College. SAO, meanwhile, hosts a long-running and highly rated REU Summer Intern program as well as many visiting graduate students. The CfA estimates that roughly 10% of the professional astrophysics community in the United States spent at least a portion of their career or education there.

    The CfA is either a lead or major partner in the operations of the Fred Lawrence Whipple Observatory, the Submillimeter Array, MMT Observatory, the South Pole Telescope, VERITAS, and a number of other smaller ground-based telescopes. The CfA’s 2019-2024 Strategic Plan includes the construction of the Giant Magellan Telescope as a driving priority for the Center.

    CFA Harvard Smithsonian Submillimeter Array on MaunaKea, Hawaii, USA, Altitude 4,205 m (13,796 ft).

    South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including The University of Chicago (US); The University of California Berkeley (US); Case Western Reserve University (US); Harvard/Smithsonian Astrophysical Observatory (US); The University of Colorado, Boulder; McGill(CA) University, The University of Illinois, Urbana-Champaign;The University of California, Davis; Ludwig Maximilians Universität München(DE); DOE’s Argonne National Laboratory; and The National Institute for Standards and Technology. The University of California, Davis; Ludwig Maximilians Universität München(DE); DOE’s Argonne National Laboratory; and The National Institute for Standards and Technology. It is funded by the National Science Foundation(US).

    Along with the Chandra X-ray Observatory, the CfA plays a central role in a number of space-based observing facilities, including the recently launched Parker Solar Probe, Kepler Space Telescope, the Solar Dynamics Observatory (SDO), and HINODE. The CfA, via the Smithsonian Astrophysical Observatory, recently played a major role in the Lynx X-ray Observatory, a NASA-Funded Large Mission Concept Study commissioned as part of the 2020 Decadal Survey on Astronomy and Astrophysics (“Astro2020”). If launched, Lynx would be the most powerful X-ray observatory constructed to date, enabling order-of-magnitude advances in capability over Chandra.

    NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker.

    SAO is one of the 13 stakeholder institutes for the Event Horizon Telescope Board, and the CfA hosts its Array Operations Center. In 2019, the project revealed the first direct image of a black hole.

    The result is widely regarded as a triumph not only of observational radio astronomy, but of its intersection with theoretical astrophysics. Union of the observational and theoretical subfields of astrophysics has been a major focus of the CfA since its founding.

    In 2018, the CfA rebranded, changing its official name to the “Center for Astrophysics | Harvard & Smithsonian” in an effort to reflect its unique status as a joint collaboration between Harvard University and the Smithsonian Institution. Today, the CfA receives roughly 70% of its funding from NASA, 22% from Smithsonian federal funds, and 4% from the National Science Foundation. The remaining 4% comes from contributors including the United States Department of Energy, the Annenberg Foundation, as well as other gifts and endowments.

     
  • richardmitnick 11:12 pm on July 7, 2021 Permalink | Reply
    Tags: "Quantum particles- Pulled and compressed", , , phys.org, , ,   

    From University of Vienna [Universität Wien] (AT) and From Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich] (CH) via phys.org : “Quantum particles- Pulled and compressed” 

    From University of Vienna [Universität Wien] (AT)

    and

    From Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich] (CH)

    via

    phys.org

    July 7, 2021

    1
    The quantum motion of a nanoparticle can be extended beyond the size of the particle using the new technique developed by. physicists in Austria. Credit: Marc Montagut.

    Very recently, researchers led by Markus Aspelmeyer at the University of Vienna and Lukas Novotny at ETH Zürich cooled a glass nanoparticle into the quantum regime for the first time. To do this, the particle is deprived of its kinetic energy with the help of lasers. What remains are movements, so-called quantum fluctuations, which no longer follow the laws of classical physics but those of quantum physics. The glass sphere with which this has been achieved is significantly smaller than a grain of sand, but still consists of several hundred million atoms. In contrast to the microscopic world of photons and atoms, nanoparticles provide an insight into the quantum nature of macroscopic objects. In collaboration with experimental physicist Markus Aspelmeyer, a team of theoretical physicists led by Oriol Romero-Isart of the University of Innsbruck [Leopold-Franzens-Universität Innsbruck] (AT) and the Institute of Quantum Optics and Quantum Information of the Austrian Academy of Sciences [Österreichische Akademie der Wissenschaften](AT) is now proposing a way to harness the quantum properties of nanoparticles for various applications.

    Briefly delocalized

    “While atoms in the motional ground state bounce around over distances larger than the size of the atom, the motion of macroscopic objects in the ground state is very, very small,” explain Talitha Weiss and Marc Roda-Llordes from the Innsbruck team. “The quantum fluctuations of nanoparticles are smaller than the diameter of an atom.” To take advantage of the quantum nature of nanoparticles, the wave function of the particles must be greatly expanded. In the Innsbruck quantum physicists’ scheme, nanoparticles are trapped in optical fields and cooled to the ground state. By rhythmically changing these fields, the particles now succeed in briefly delocalizing over exponentially larger distances. “Even the smallest perturbations may destroy the coherence of the particles, which is why by changing the optical potentials, we only briefly pull apart the wave function of the particles and then immediately compress it again,” explains Oriol Romero-Isart. By repeatedly changing the potential, the quantum properties of the nanoparticle can thus be harnessed.

    Many applications

    With the new technique, the macroscopic quantum properties can be studied in more detail. It also turns out that this state is very sensitive to static forces. Thus, the method could enable highly sensitive instruments that can be used to determine forces such as gravity very precisely. Using two particles expanded and compressed simultaneously by this method, it would also be possible to entangle them via a weak interaction and explore entirely new areas of the macroscopic quantum world.

    Together with other proposals, the new concept forms the basis for the ERC Synergy Grant project Q-Xtreme, which was granted last year. In this project, the research groups of Markus Aspelmeyer and Oriol Romero-Isart, together with Lukas Novotny and Romain Quidant of ETH Zürich, are pushing one of the most fundamental principles of quantum physics to the extreme limit by positioning a solid body of billions of atoms in two places at the same time.

    Science paper:
    Physical Review Letters

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    ETH Zurich campus
    Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich] (CH) is a public research university in the city of Zürich, Switzerland. Founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists, the school focuses exclusively on science, technology, engineering and mathematics. Like its sister institution Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne](CH) , it is part of the Swiss Federal Institutes of Technology Domain (ETH Domain)) , part of the Swiss Federal Department of Economic Affairs, Education and Research [EAER][Eidgenössisches Departement für Wirtschaft, Bildung und Forschung] [Département fédéral de l’économie, de la formation et de la recherche] (CH).

    The university is an attractive destination for international students thanks to low tuition fees of 809 CHF per semester, PhD and graduate salaries that are amongst the world’s highest, and a world-class reputation in academia and industry. There are currently 22,200 students from over 120 countries, of which 4,180 are pursuing doctoral degrees. In the 2021 edition of the QS World University Rankings ETH Zürich is ranked 6th in the world and 8th by the Times Higher Education World Rankings 2020. In the 2020 QS World University Rankings by subject it is ranked 4th in the world for engineering and technology (2nd in Europe) and 1st for earth & marine science.

    As of November 2019, 21 Nobel laureates, 2 Fields Medalists, 2 Pritzker Prize winners, and 1 Turing Award winner have been affiliated with the Institute, including Albert Einstein. Other notable alumni include John von Neumann and Santiago Calatrava. It is a founding member of the IDEA League and the International Alliance of Research Universities (IARU) and a member of the CESAER network.

    ETH Zürich was founded on 7 February 1854 by the Swiss Confederation and began giving its first lectures on 16 October 1855 as a polytechnic institute (eidgenössische polytechnische Schule) at various sites throughout the city of Zurich. It was initially composed of six faculties: architecture, civil engineering, mechanical engineering, chemistry, forestry, and an integrated department for the fields of mathematics, natural sciences, literature, and social and political sciences.

    It is locally still known as Polytechnikum, or simply as Poly, derived from the original name eidgenössische polytechnische Schule, which translates to “federal polytechnic school”.

    ETH Zürich is a federal institute (i.e., under direct administration by the Swiss government), whereas the University of Zürich [Universität Zürich ] (CH) is a cantonal institution. The decision for a new federal university was heavily disputed at the time; the liberals pressed for a “federal university”, while the conservative forces wanted all universities to remain under cantonal control, worried that the liberals would gain more political power than they already had. In the beginning, both universities were co-located in the buildings of the University of Zürich.

    From 1905 to 1908, under the presidency of Jérôme Franel, the course program of ETH Zürich was restructured to that of a real university and ETH Zürich was granted the right to award doctorates. In 1909 the first doctorates were awarded. In 1911, it was given its current name, Eidgenössische Technische Hochschule. In 1924, another reorganization structured the university in 12 departments. However, it now has 16 departments.

    ETH Zürich, EPFL (Swiss Federal Institute of Technology in Lausanne) [École polytechnique fédérale de Lausanne](CH), and four associated research institutes form the Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles polytechniques fédérales] (CH) with the aim of collaborating on scientific projects.

    Reputation and ranking

    ETH Zürich is ranked among the top universities in the world. Typically, popular rankings place the institution as the best university in continental Europe and ETH Zürich is consistently ranked among the top 1-5 universities in Europe, and among the top 3-10 best universities of the world.

    Historically, ETH Zürich has achieved its reputation particularly in the fields of chemistry, mathematics and physics. There are 32 Nobel laureates who are associated with ETH Zürich, the most recent of whom is Richard F. Heck, awarded the Nobel Prize in chemistry in 2010. Albert Einstein is perhaps its most famous alumnus.

    In 2018, the QS World University Rankings placed ETH Zürich at 7th overall in the world. In 2015, ETH Zürich was ranked 5th in the world in Engineering, Science and Technology, just behind the Massachusetts Institute of Technology(US), Stanford University(US) and University of Cambridge(UK). In 2015, ETH Zürich also ranked 6th in the world in Natural Sciences, and in 2016 ranked 1st in the world for Earth & Marine Sciences for the second consecutive year.

    In 2016, Times Higher Education WorldUniversity Rankings ranked ETH Zürich 9th overall in the world and 8th in the world in the field of Engineering & Technology, just behind the Massachusetts Institute of Technology(US), Stanford University(US), California Institute of Technology(US), Princeton University(US), University of Cambridge(UK), Imperial College London(UK) and University of Oxford(UK).

    In a comparison of Swiss universities by swissUP Ranking and in rankings published by CHE comparing the universities of German-speaking countries, ETH Zürich traditionally is ranked first in natural sciences, computer science and engineering sciences.

    In the survey CHE ExcellenceRanking on the quality of Western European graduate school programs in the fields of biology, chemistry, physics and mathematics, ETH Zürich was assessed as one of the three institutions to have excellent programs in all the considered fields, the other two being Imperial College London(UK) and the University of Cambridge(UK), respectively.

    Universität Wien Campus

    University of Vienna [Universität Wien](AT) is a public university located in Vienna, Austria.It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich history, the University of Vienna has developed into one of the largest universities in Europe, and also one of the most renowned, especially in the Humanities. It is associated with 21 Nobel prize winners and has been the academic home to many scholars of historical as well as of academic importance.

    From the Middle Ages to the Enlightenment

    The University was founded on 12 March 1365 by Rudolf IV, Duke of Austria, and his two brothers, Dukes Albert III and Leopold III, hence the additional name “Alma Mater Rudolphina”. After the Charles University in Prague [Univerzita Karlova](CZ) and Jagiellonian University [Uniwersytet Jagielloński](PL), the University of Vienna is the third oldest university in Central Europe and the oldest university in the contemporary German-speaking world; it remains a question of definition as the Charles University in Prague [Univerzita Karlova](CZ) was German-speaking when founded, too.

    The University of Vienna was modelled after the University of Paris [Université de Paris](FR). However, Pope Urban V did not ratify the deed of foundation that had been sanctioned by Rudolf IV, specifically in relation to the department of theology. This was presumably due to pressure exerted by Charles IV, Holy Roman Emperor, who wished to avoid competition for the Charles University in Prague. Approval was finally received from the Pope in 1384 and the University of Vienna was granted the status of a full university, including the Faculty of Catholic Theology. The first university building opened in 1385. It grew into the biggest university of the Holy Roman Empire, and during the advent of Humanism in the mid-15th century was home to more than 6,000 students.

    In its early years, the university had a partly hierarchical, partly cooperative structure, in which the Rector was at the top, while the students had little say and were settled at the bottom. The Magister and Doctors constituted the four faculties and elected the academic officials from amidst their ranks. The students, but also all other Supposita (university members), were divided into four Academic Nations. Their elected board members, mostly graduates themselves, had the right to elect the Rector. He presided over the Consistory which included procurators of each of the nations and the faculty deans, as well as over the University Assembly, in which all university teachers participated. Complaints or appeals against decisions of faculty by the students had to be brought forward by a Magister or Doctor.

    Being considered a Papal Institution, the university suffered quite a setback during the Reformation. In addition, the first Siege of Vienna by Ottoman forces had devastating effects on the city, leading to a sharp decline, with only 30 students enrolled at the lowest point. For King Ferdinand I, this meant that the university should be tied to the church to an even stronger degree, and in 1551 he installed the Jesuit Order there. With the enacting of the Sanctio Pragmatica edict by emperor Ferdinand II in 1623, the Jesuits took over teaching at the theological and philosophical faculty, and thus the university became a stronghold of Catholicism for over 150 years. It was only in the Mid-18th century that Empress Maria Theresa forced the university back under control of the monarchy. Her successor Joseph II helped in the further reform of the university, allowing both Protestants and Jews to enroll as well as introducing German as the compulsory language of instruction.

    From the 19th Century Onwards

    Big changes were instituted in the wake of the Revolution in 1848, with the Philosophical Faculty being upgraded into equal status as Theology, Law and Medicine. Led by the reforms of Leopold, Count von Thun und Hohenstein, the university was able to achieve a larger degree of academic freedom. The current main building on the Ringstraße was built between 1877 and 1884 by Heinrich von Ferstel. The previous main building was located close to the Stuben Gate (Stubentor) on Iganz Seipel Square, current home of the old University Church (Universitätskirche) and the Austrian Academy of Sciences [Österreichische Akademie der Wissenschaften(AT). Women were admitted as full students from 1897, although their studies were limited to Philosophy. The remaining departments gradually followed suit, although with considerable delay: Medicine in 1900, Law in 1919, Protestant Theology in 1923 and finally Roman Catholic Theology in 1946. Ten years after the admission of the first female students, Elise Richter became the first woman to receive habilitation, becoming professor of Romance Languages in 1907; she was also the first female distinguished professor.

    In the late 1920s, the university was in steady turmoil because of anti-democratic and anti-Semitic activity by parts of the student body. Professor Moritz Schlick was killed by a former student while ascending the steps of the University for a class. His murderer was later released by the Nazi Regime. Following the Anschluss, the annexation of Austria into Greater Germany by the Nazi regime, in 1938 the University of Vienna was reformed under political aspects and a huge number of teachers and students were dismissed for political and “racial” reasons. In April 1945, the then 22-year-old Kurt Schubert, later acknowledged doyen of Judaic Studies at the University of Vienna, was permitted by the Soviet occupation forces to open the university again for teaching, which is why he is regarded as the unofficial first rector in the post-war period. On 25 April 1945, however, the constitutional lawyer Ludwig Adamovich senior was elected as official rector of the University of Vienna. A large degree of participation by students and university staff was realized in 1975, however the University Reforms of 1993 and 2002 largely re-established the professors as the main decision makers. However, also as part of the last reform, the university after more than 250 years being largely under governmental control, finally regained its full legal capacity. The number of faculties and centers was increased to 18, and the whole of the medical faculty separated into the new Medical University of Vienna [Medizinische Universität Wien](AT).

     
  • richardmitnick 4:07 pm on July 7, 2021 Permalink | Reply
    Tags: "Like a molten pancake: A new model for shield volcano eruption", , , phys.org,   

    From GSI Helmholtz Association of German Research Centres [Helmholtz-Gemeinschaft Deutscher Forschungszentren GmbH] (DE) via phys.org : “Like a molten pancake: A new model for shield volcano eruption” 

    From GSI Helmholtz Association of German Research Centres [Helmholtz-Gemeinschaft Deutscher Forschungszentren GmbH] (DE)

    via

    phys.org

    July 7, 2021

    1
    Hawaii Volcanoes National Park. May 1954 eruption of Kilauea Volcano. Halemaumau fountains. Photo by J.P. Eaton, May 31, 1954.

    2
    Erta Ale is an active shield volcano located in the Afar Region of northeastern Ethiopia, within the Danakil Desert. It is the most active volcano in Ethiopia. Credit: filippo_jean

    There are some large shield volcanoes in the world’s oceans where the lava is usually not ejected from the crater in violent explosions, but flows slowly out of the ground from long fissures. In the recent eruption of the Sierra Negra volcano in the Galapagos Islands, which lie just under a thousand kilometers off South America in the Pacific Ocean, one of these fissures was fed through a curved pathway in June 2018.

    4
    Sierra Negra Volcano Eruption – June 2018. Credit: Allie Savage.

    This 15 kilometer-long pathway, including the kink, was created by the interaction of three different forces in the subsurface, Timothy Davis and Eleonora Rivalta from the GFZ German Research Centre for Geosciences in Potsdam, together with Marco Bagnardi and Paul Lundgren from NASA’s Jet Propulsion Laboratory (US) in Pasadena, now explain based on computer models in the journal Geophysical Research Letters.

    Even before the eruption, the geoscientists in California had seen in radar satellite data that the surface of the flank of the 1140-meter-high Sierra Negra volcano had bulged to a height of about two meters: this bulge, about five kilometers wide, stretched from the crater rim about ten kilometers in a west-northwest direction and turned at a right angle to the north-northeast near the coast. Timothy Davis and his team then found out what this structure and its perplexing bend were all about with the help of computer models.

    Driving Force 1: Hotspot beneath the Galapagos Islands

    As with many other volcanoes in the middle of the world’s oceans, a “hotspot” is hidden beneath the Galapagos Islands. For at least 20 million years, hot rock has been rising slowly from deep within the Earth’s interior, like a solid, but difficult-to-form plasticine. Like a blowtorch, this hotspot, up to 200 kilometers wide, melts its way through the solid crust of the Earth. This hot magma is a little lighter than the solid rock around it, so it keeps rising until it collects in a large cavity about two kilometers below the crater of the Sierra Negra volcano. “With a diameter of around six kilometers and a thickness of no more than one kilometer, this magma chamber resembles an oversized pancake of molten rock,” Timothy Davis describes this structure.

    Driving Force 2: The weight of the volcano rock

    In the almost 13 years since the last eruption in October 2005, more and more magma has flowed into the chamber from below. There, the pressure rose and lifted the crater floor up to 5.20 meters. However, the enormous force of the gathering magma masses sought another way out. Deep underground, the viscous rock slowly crawled in a west-northwest direction. Another force plays an important role here: the enormous weight of the volcano’s rock masses presses from above on the magma flow that is just forming. As the shield volcano becomes flatter and flatter towards the outside, the pressure there also decreases. As the molten rock is pressed in the direction with lower pressure, it slowly swells outwards in a magma flow that is four kilometers wide but only about two meters high.

    Driving Force 3: Buoyancy

    Near the coastline, the flattening shield volcano presses ever more weakly on the now almost ten-kilometer-long magma corridor deep below the surface. There, a third force gains the upper hand. The magma is much lighter than the rock around the passage and was previously only prevented from swelling by the overlying weight of the shield volcano. Near the coastline, however, this buoyancy becomes stronger than the pressure of the rock from above. On top of that, the magma slope there tilts about ten degrees into the depths. Together, these forces change the direction in which the viscous rock is pressed and the magma slope bends towards the north-northeast.

    The rock cracks, the volcano erupts

    Still, the magma swelling under the crater continues to increase the pressure until the upward-pressing molten mass begins to crack the rock around the magma passage. At no more than walking speed, this magma-filled crack (dyke) is traveling deep underground towards the coastline. “The magma rising from the crack reaches the surface after a few days and continues to flow there as lava, which solidifies after some time,” Timothy Davis explains the subsequent course of the volcanic eruption.

    Important prerequisite for prediction and hazard minimization

    For the first time, the geophysicist was able to simulate such a tortuous magma propagation pathway feeding an eruption and determine the forces that control this. Timothy Davis and Eleonora Rivalta, together with their colleagues in California, have thus laid important foundations for research into such fissure eruptions. And they have taken a decisive step towards predicting such eruptions and thus reducing the dangers they pose.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Helmholtz Zentrum München (DE) by numbers.

    The Helmholtz Association of German Research Centres [[Helmholtz-Gemeinschaft Deutscher Forschungszentren GmbH] (DE) is the largest scientific organization in Germany. It is a union of 18 scientific-technical and biological-medical research centers. The official mission of the Association is “solving the grand challenges of science, society and industry”. Scientists at Helmholtz therefore focus research on complex systems which affect human life and the environment. The namesake of the association is the German physiologist and physicist Hermann von Helmholtz.
    The annual budget of the Helmholtz Association amounts to €4.56 billion, of which about 72% is raised from public funds. The remaining 28% of the budget is acquired by the 19 individual Helmholtz Centres in the form of contract funding. The public funds are provided by the federal government (90%) and the rest by the States of Germany (10%).
    The Helmholtz Association was ranked #8 in 2015 and #7 in 2017 by the Nature Index, which measures the largest contributors to papers published in 82 leading journals.

    The laboratory performs basic and applied research in physics and related natural science disciplines. Main fields of study include plasma physics, atomic physics, nuclear structure and reactions research, biophysics and medical research. The lab is a member of the Helmholtz Association of German Research Centres.

     
  • richardmitnick 3:24 pm on July 7, 2021 Permalink | Reply
    Tags: "Nanosecond Plasmas in Liquids - How do they ignite?", , , , phys.org, , The in-liquid discharges are usually ignited in a pin-to-pin or pin-to-plate configuration using a high voltage (HV) pulse applied to an electrode.   

    From Ruhr-Universität Bochum (DE) via phys.org : “Nanosecond Plasmas in Liquids – How do they ignite?” 

    From Ruhr-Universität Bochum (DE)

    via

    phys.org

    July 7, 2021

    1
    The ignition of plasma under water. Credit: Damian Gorczany.

    2

    Discharges in liquids gained a huge interest over the last decades as they can be used for example for wastewater treatment, for nanoparticle formation as well as for biomedical applications . These types of discharges are appealing, because they produce a range of reactive species like OH and H2O2 inside water. The in-liquid discharges are usually ignited in a pin-to-pin or pin-to-plate configuration using a high voltage (HV) pulse applied to an electrode. The mechanism responsible for breakdown in liquids was initially associated with the breakdown of vapor in previously formed bubbles which are created at the tip of the powered electrode – such an the ignition environment is more gaseous than a direct liquid environment.

    In comparison to that, nanosecond (ns) pulsed discharges with short rising times of the voltage of a few ns in water are assumed to ignite directly inside water . The ignition may occur via the Townsend mechanisms in the gas phase of vapor that is trapped in small nanovoids. Such nanovoids, may be created by the high electric fields that cause ruptures in the liquid. Alternatively, ignition may also occur by field emission and/or field ionization at the liquid solid interface. Due to the high electric field at the electrode tip, the potential barrier between the metal and adjacent water molecules is modified so that electrons are able to tunnel through the potential barrier. In case of a positive potential, this tunneling causes the formation of positive water ions by field ionization. In case of a negative voltage, tunneling causes the acceleration of electrons into the liquid, that may cause impact ionization of water molecules.

    The understanding of the ignition process is crucial to understand the evolution of the chemistry of water dissociation. For example, if a bubble is present prior to ignition, a plasma from vapor is created and the dissociation products would then dissolve into the water at the end of the pulse. On the other hand, if the discharge is created directly inside water, aqueous electrons would be created and dissociation may occur directly in a very high pressure environment.

    Science paper:
    Journal of Applied Physics

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Ruhr-Universität Bochum (DE) is a public university located in the southern hills of the central Ruhr area in Bochum. It was founded in 1962 as the first new public university in Germany after World War II. Instruction began in 1965.

    The Ruhr-University Bochum is one of the largest universities in Germany and part of the Deutsche Forschungsgemeinschaft, the most important German research funding organization.

    The RUB was very successful in the Excellence Initiative of the German Federal and State Governments (2007), a competition between Germany’s most prestigious universities. It was one of the few institutions left competing for the title of an “elite university”, but did not succeed in the last round of the competition. There are currently nine universities in Germany that hold this title.

    The University of Bochum was one of the first universities in Germany to introduce international bachelor’s and master’s degrees, which replaced the traditional German Diplom and Magister. Except for a few special cases (for example in Law) these degrees are offered by all faculties of the Ruhr-University. Currently, the university offers a total of 184 different study programs from all academic fields represented at the university.

     
  • richardmitnick 4:49 pm on July 5, 2021 Permalink | Reply
    Tags: "Sculpted by starlight- A meteorite witness to the solar system's birth", Acfer 094 contains porous regions and tiny grains that formed around other stars., Acfer 094 is one of the most primitive meteorites in our collection., , Asteroids and planets formed from the same presolar material but they've been influenced by different natural processes., , , Neighboring massive stars were likely close enough that their light affected the solar system's formation., Oxygen isotopes in the sun differ from those found on Earth; the moon; and the other planets and satellites in the solar system., phys.org, Starlight had a profound effect on our origins., Sulfur's four isotopes would leave their marks in different ratios depending on the spectrum of ultraviolet light., The meteorite Acfer 094 found in Algeria in 1990, The scientists the idea of sulfur isotopes., The sulfur isotope measurements of cosmic symplectite were consistent with ultraviolet irradiation from a massive star but did not fit the UV spectrum from the young sun., Today we can look to the skies and see a similar origin story play out elsewhere in the galaxy., , We see nascent planetary systems called proplyds in the Orion nebula that are being photoevaporated by ultraviolet light from nearby massive O and B stars., With only three isotopes of oxygen simply finding the heavy oxygen isotopes wasn't enough to answer the question of the origin of the light.   

    From Washington University in St. Louis via phys.org : “Sculpted by starlight- A meteorite witness to the solar system’s birth” 

    Wash U Bloc

    From Washington University in St. Louis

    via

    phys.org

    July 5, 2021
    Brandie Jefferson, Washington University in St. Louis

    1
    Cosmic symplectite in the meteorite Acfer 094. Credit: Ryan Ogliore, Laboratory for Space Sciences.

    In 2011, scientists confirmed a suspicion: There was a split in the local cosmos. Samples of the solar wind brought back to Earth by the Genesis mission definitively determined oxygen isotopes in the sun differ from those found on Earth; the moon; and the other planets and satellites in the solar system.

    Early in the solar system’s history, material that would later coalesce into planets had been hit with a hefty dose of ultraviolet light, which can explain this difference. Where did it come from? Two theories emerged: Either the ultraviolet light came from our then-young sun, or it came from a large nearby star in the sun’s stellar nursery.

    Now, researchers from the lab of Ryan Ogliore, assistant professor of physics in Arts & Sciences at Washington University in St. Louis, have determined which was responsible for the split. It was most likely light from a long-dead massive star that left this impression on the rocky bodies of the solar system. The study was led by Lionel Vacher, a postdoctoral research associate in the physics department’s Laboratory for Space Sciences.

    Their results are published in the journal Geochimica et Cosmochimica Acta.

    “We knew that we were born of stardust: that is, dust created by other stars in our galactic neighborhood were part of the building blocks of the solar system,” Ogliore said.

    “But this study showed that starlight had a profound effect on our origins as well.”

    Tiny time capsule

    All of that profundity was packed into a mere 85 grams of rock, a piece of an asteroid found as a meteorite in Algeria in 1990, named Acfer 094. Asteroids and planets formed from the same presolar material but they’ve been influenced by different natural processes. The rocky building blocks that coalesced to form asteroids and planets were broken up and battered; vaporized and recombined; and compressed and heated. But the asteroid that Acfer 094 came from managed to survive for 4.6 billion years mostly unscathed.

    “This is one of the most primitive meteorites in our collection,” Vacher said. “It was not heated significantly. It contains porous regions and tiny grains that formed around other stars. It is a reliable witness to the solar system’s formation.”

    Acfer 094 is also the only meteorite that contains cosmic symplectite, an intergrowth of iron-oxide and iron-sulfide with extremely heavy oxygen isotopes—a significant finding.

    The sun contains about 6% more of the lightest oxygen isotope compared with the rest of the solar system. That can be explained by ultraviolet light shining on the solar system’s building blocks, selectively breaking apart carbon monoxide gas into its constituent atoms. That process also creates a reservoir of much heavier oxygen isotopes. Until cosmic symplectite, however, no one had found this heavy isotope signature in samples of solar system materials.

    With only three isotopes simply finding the heavy oxygen isotopes wasn’t enough to answer the question of the origin of the light. Different ultraviolet spectra could have created the same result.

    2
    181-825 is one of the bright proplyds — protoplanetary disks — that lies relatively close to the Orion nebula’s brightest star, Theta 1 Orionis C. Resembling a tiny jellyfish, this proplyd is surrounded by a shock wave that is caused by stellar wind from the massive Theta 1 Orionis C interacting with gas in the nebula. Credit: Credit: National Aeronautics Space Agency (US)/European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU) and L. Ricci [European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte] (EU) (CL)].

    “That’s when Ryan came up with the idea of sulfur isotopes,” Vacher said.

    Sulfur’s four isotopes would leave their marks in different ratios depending on the spectrum of ultraviolet light that irradiated hydrogen sulfide gas in the proto-solar system. A massive star and a young sun-like star have different ultraviolet spectra.

    Cosmic symplectite formed when ices on the asteroid melted and reacted with small pieces of iron-nickel metal. In addition to oxygen, cosmic symplectite contains sulfur in iron sulfide. If its oxygen witnessed this ancient astrophysical process—which led to the heavy oxygen isotopes—perhaps its sulfur did, too.

    “We developed a model,” Ogliore said. “If I had a massive star, what isotope anomalies would be created? What about for a young, sun-like star? The precision of the model depends on the experimental data. Fortunately, other scientists have done great experiments on what happens to isotope ratios when hydrogen sulfide is irradiated by ultraviolet light.”

    Sulfur and oxygen isotope measurements of cosmic symplectite in Acfer 094 proved another challenge. The grains, tens of micrometers in size and a mixture of minerals, required new techniques on two different in-situ secondary-ion mass spectrometers: the NanoSIMS in the physics department (with assistance from Nan Liu, research assistant professor in physics) and the 7f-GEO in the Department of Earth and Planetary Sciences, also in Arts & Sciences.

    Putting the puzzle together

    It helped to have friends in earth and planetary sciences, particularly David Fike, professor of earth and planetary sciences and director of Environmental Studies in Arts & Sciences as well as director of the International Center for Energy, Environment and Sustainability, and Clive Jones, research scientist in earth and planetary sciences.

    “They are experts in high-precision in-situ sulfur isotope measurements for biogeochemistry,” Ogliore said. “Without this collaboration, we would not have achieved the precision we needed to differentiate between the young sun and massive star scenarios.”

    The sulfur isotope measurements of cosmic symplectite were consistent with ultraviolet irradiation from a massive star but did not fit the UV spectrum from the young sun. The results give a unique perspective on the astrophysical environment of the sun’s birth 4.6 billion years ago. Neighboring massive stars were likely close enough that their light affected the solar system’s formation. Such a nearby massive star in the night sky would appear brighter than the full moon.

    Today we can look to the skies and see a similar origin story play out elsewhere in the galaxy.

    “We see nascent planetary systems called proplyds in the Orion nebula that are being photoevaporated by ultraviolet light from nearby massive O and B stars,” Vacher said.

    “If the proplyds are too close to these stars, they can be torn apart, and planets never form. We now know our own solar system at its birth was close enough to be affected by the light of these stars,” he said. “But thankfully, not too close.”This work was supported by the McDonnell Center for Space Sciences at Washington University in St. Louis and NASA grant NNX14AF22G.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Wash U campus

    Washington University in St. Louis is a private research university in Greater St. Louis with its main campus (Danforth) mostly in unincorporated St. Louis County, Missouri, and Clayton, Missouri. It also has a West Campus in Clayton, North Campus in the West End neighborhood of St. Louis, Missouri, and Medical Campus in the Central West End neighborhood of St. Louis, Missouri.

    Founded in 1853 and named after George Washington, the university has students and faculty from all 50 U.S. states and more than 120 countries. Washington University is composed of seven graduate and undergraduate schools that encompass a broad range of academic fields. To prevent confusion over its location, the Board of Trustees added the phrase “in St. Louis” in 1976. Washington University is a member of the Association of American Universities (US) and is classified among “R1: Doctoral Universities – Very high research activity”.

    As of 2020, 25 Nobel laureates in economics, physiology and medicine, chemistry, and physics have been affiliated with Washington University, ten having done the major part of their pioneering research at the university. In 2019, Clarivate Analytics ranked Washington University 7th in the world for most cited researchers. The university also received the 4th highest amount of National Institutes of Health (US) medical research grants among medical schools in 2019.

    Research

    Virtually all faculty members at Washington University engage in academic research, offering opportunities for both undergraduate and graduate students across the university’s seven schools. Known for its interdisciplinary and departmental collaboration, many of Washington University’s research centers and institutes are collaborative efforts between many areas on campus. More than 60% of undergraduates are involved in faculty research across all areas; it is an institutional priority for undergraduates to be allowed to participate in advanced research. According to the Center for Measuring University Performance, it is considered to be one of the top 10 private research universities in the nation. A dedicated Office of Undergraduate Research is located on the Danforth Campus and serves as a resource to post research opportunities, advise students in finding appropriate positions matching their interests, publish undergraduate research journals, and award research grants to make it financially possible to perform research.

    According to the National Science Foundation (US), Washington University spent $816 million on research and development in 2018, ranking it 27th in the nation. The university has over 150 National Institutes of Health funded inventions, with many of them licensed to private companies. Governmental agencies and non-profit foundations such as the NIH, Department of Defense (US), National Science Foundation, and National Aeronautics Space Agency (US) provide the majority of research grant funding, with Washington University being one of the top recipients in NIH grants from year-to-year. Nearly 80% of NIH grants to institutions in the state of Missouri went to Washington University alone in 2007. Washington University and its Medical School play a large part in the Human Genome Project, where it contributes approximately 25% of the finished sequence. The Genome Sequencing Center has decoded the genome of many animals, plants, and cellular organisms, including the platypus, chimpanzee, cat, and corn.

    NASA hosts its Planetary Data System Geosciences Node on the campus of Washington University. Professors, students, and researchers have been heavily involved with many unmanned missions to Mars. Professor Raymond Arvidson has been deputy principal investigator of the Mars Exploration Rover mission and co-investigator of the Phoenix lander robotic arm.

    Washington University professor Joseph Lowenstein, with the assistance of several undergraduate students, has been involved in editing, annotating, making a digital archive of the first publication of poet Edmund Spenser’s collective works in 100 years. A large grant from the National Endowment for the Humanities (US) has been given to support this ambitious project centralized at Washington University with support from other colleges in the United States.

    In 2019, Folding@Home (US), a distributed computing project for performing molecular dynamics simulations of protein dynamics, was moved to Washington University School of Medicine from Stanford University (US). The project, currently led by Dr. Greg Bowman, uses the idle CPU time of personal computers owned by volunteers to conduct protein folding research. Folding@home’s research is primarily focused on biomedical problems such as Alzheimer’s disease, Cancer, Coronavirus disease 2019, and Ebola virus disease. In April 2020, Folding@home became the world’s first exaFLOP computing system with a peak performance of 1.5 exaflops, making it more than seven times faster than the world’s fastest supercomputer, Summit, and more powerful than the top 100 supercomputers in the world, combined.

     
  • richardmitnick 1:15 pm on July 5, 2021 Permalink | Reply
    Tags: "Europa Clipper to determine whether icy moon has ingredients necessary for life", , Johns Hopkins University (US), phys.org,   

    From Johns Hopkins University (US) via phys.org : “Europa Clipper to determine whether icy moon has ingredients necessary for life” 

    From Johns Hopkins University (US)

    via

    phys.org

    July 5, 2021
    Ashley Stimpson, Johns Hopkins University

    1
    Credit: Eric Nyquist.

    In 1610, Galileo peered through his telescope and spotted four bright moons orbiting Jupiter, dispelling the long-held notion that all celestial bodies revolved around the Earth. In 2024, when scientists expect to send the Europa Clipper spacecraft to investigate one of those moons, they too may find evidence that fundamentally alters our understanding of the solar system.

    Europa is the sixth nearest moon to Jupiter and is roughly the same size as our own. Thanks to data retrieved by the Galileo space probe—launched in 1989 and named to honor the Italian astronomer—and the Hubble Space Telescope, scientists are almost sure that a salty, liquid ocean is hidden beneath Europa’s icy surface, one so large that astronomers believe it could contain two times the water in all of Earth’s oceans combined.

    Europa itself has been around for 4.5 billion years, but its surface is geologically young, only about 60 million years old, suggesting that it has been continually resurfaced, perhaps through a process much like Earth’s shifting plate tectonics. As Europa travels around Jupiter, its elliptical orbit and the planet’s strong gravitational pull cause the moon to flex like a rubber ball, producing heat that’s capable of maintaining an ocean’s liquid state. Hydrothermal energy at the moon’s core, left over from its formation, may also heat the ocean at the seafloor.

    These unique characteristics have led NASA to deem Europa “the most promising place in our solar system to find present-day environments suitable for some form of life beyond Earth.” But in order for life to exist, it needs more than just water and energy. It also needs essential chemicals like hydrogen, carbon, and oxygen. While Europa seems to check the first two boxes, its composition remains a mystery. Confirming all three of these ingredients for life will determine whether Europa is habitable.

    “That’s the $4 billion question,” says Haje Korth, a space physicist at the Johns Hopkins Applied Physics Lab and deputy project scientist for the Europa Clipper mission. He and his colleagues at NASA and its California-based Jet Propulsion Lab are gearing up to investigate whether Europa might contain the ingredients necessary for life somewhere in its vast ocean.

    In late 2024, they will send the orbiter into the skies above Cape Canaveral, where it will begin its five-and-a-half-year journey to Europa. During that time it will fly by both Mars and Earth, using the planets’ gravity to slingshot itself 484 million miles toward Jupiter, arriving by 2030. Kate Craft, one of the mission’s project staff scientists, warns the long journey will precede even greater challenges.

    “The radiation from Jupiter is really harsh,” she says. “Our instruments have to be able to survive that.”


    Alien Ocean: NASA’s Mission to Europa. Credit: JHU.

    Roughly the size of a basketball court, the Europa Clipper will carry an impressive suite of 10 separate instruments. Korth says getting all those gadgets to work simultaneously—in the frigid temperatures of outer space, no less—will be another test.

    Two cameras, so powerful they will be able to pick up features just a few feet long, will map the moon’s surface in color and from multiple angles. Spectrometers will study the chemical makeup of Europa’s surface as well as the particles that hover above it. A magnetometer will be able to determine the depth and salinity of Europa’s ocean.

    Two more instruments, a thermal emission imaging system and an ultraviolet spectrograph, will look for areas where Europa’s ocean may have spilled out onto the surface via eruptions or plumes. If scientists find such a location, they would be able to analyze the composition of Europa’s ocean without ever touching down on its surface.

    “These would be the most pristine samples of the ocean underneath,” Korth says. “This is not a plume-hunting mission, but we’ll certainly take that opportunity.”

    Clipper will spend three and a half years in orbit around Jupiter, performing a flyby of Europa every two to three weeks from as close as 16 miles away, sending back observations that will reach Earth in as little as a week. Between flybys, scientists will pore over this cache of data, adjusting the observations if they see something that sparks their interest—a plume, for example—or necessitates further investigation. Right now, the mission team has planned 45 flybys, but the tour could be extended if funding allows.

    While launch is still more than three years away, Craft is already part of multiple studies determining the feasibility and logistics of a Europa Lander mission, the next logical step if Europa Clipper finds the moon to be habitable. A lander could be delivered to Europa from a sky crane—much like the recent Mars Perseverance—and house a cryobot designed to drill through the icy shell and into the ocean below.

    Europa’s subsurface waters aren’t the only outer-space oceans that APL has its eyes on. In October 2020, the Lab announced it would pitch NASA on the Enceladus Orbilander, a spacecraft designed to orbit and land on Saturn’s sixth-largest moon to search for signs of life hidden in its ocean.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Johns Hopkins Unversity campus.

    The Johns Hopkins University (US) opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

    The Johns Hopkins University (US) is a private research university in Baltimore, Maryland. Founded in 1876, the university was named for its first benefactor, the American entrepreneur and philanthropist Johns Hopkins. His $7 million bequest (approximately $147.5 million in today’s currency)—of which half financed the establishment of the Johns Hopkins Hospital—was the largest philanthropic gift in the history of the United States up to that time. Daniel Coit Gilman, who was inaugurated as the institution’s first president on February 22, 1876, led the university to revolutionize higher education in the U.S. by integrating teaching and research. Adopting the concept of a graduate school from Germany’s historic Ruprecht Karl University of Heidelberg, [Ruprecht-Karls-Universität Heidelberg] (DE), Johns Hopkins University is considered the first research university in the United States. Over the course of several decades, the university has led all U.S. universities in annual research and development expenditures. In fiscal year 2016, Johns Hopkins spent nearly $2.5 billion on research. The university has graduate campuses in Italy, China, and Washington, D.C., in addition to its main campus in Baltimore.

    Johns Hopkins is organized into 10 divisions on campuses in Maryland and Washington, D.C., with international centers in Italy and China. The two undergraduate divisions, the Zanvyl Krieger School of Arts and Sciences and the Whiting School of Engineering, are located on the Homewood campus in Baltimore’s Charles Village neighborhood. The medical school, nursing school, and Bloomberg School of Public Health, and Johns Hopkins Children’s Center are located on the Medical Institutions campus in East Baltimore. The university also consists of the Peabody Institute, Applied Physics Laboratory, Paul H. Nitze School of Advanced International Studies, School of Education, Carey Business School, and various other facilities.

    Johns Hopkins was a founding member of the American Association of Universities (US). As of October 2019, 39 Nobel laureates and 1 Fields Medalist have been affiliated with Johns Hopkins. Founded in 1883, the Blue Jays men’s lacrosse team has captured 44 national titles and plays in the Big Ten Conference as an affiliate member as of 2014.

    Research

    The opportunity to participate in important research is one of the distinguishing characteristics of Hopkins’ undergraduate education. About 80 percent of undergraduates perform independent research, often alongside top researchers. In FY 2013, Johns Hopkins received $2.2 billion in federal research grants—more than any other U.S. university for the 35th consecutive year. Johns Hopkins has had seventy-seven members of the Institute of Medicine, forty-three Howard Hughes Medical Institute Investigators, seventeen members of the National Academy of Engineering, and sixty-two members of the National Academy of Sciences. As of October 2019, 39 Nobel Prize winners have been affiliated with the university as alumni, faculty members or researchers, with the most recent winners being Gregg Semenza and William G. Kaelin.

    Between 1999 and 2009, Johns Hopkins was among the most cited institutions in the world. It attracted nearly 1,222,166 citations and produced 54,022 papers under its name, ranking No. 3 globally [after Harvard University (US) and the Max Planck Society (DE)] in the number of total citations published in Thomson Reuters-indexed journals over 22 fields in America.

    In FY 2000, Johns Hopkins received $95.4 million in research grants from the National Aeronautics and Space Administration (US), making it the leading recipient of NASA research and development funding. In FY 2002, Hopkins became the first university to cross the $1 billion threshold on either list, recording $1.14 billion in total research and $1.023 billion in federally sponsored research. In FY 2008, Johns Hopkins University performed $1.68 billion in science, medical and engineering research, making it the leading U.S. academic institution in total R&D spending for the 30th year in a row, according to a National Science Foundation (US) ranking. These totals include grants and expenditures of JHU’s Applied Physics Laboratory in Laurel, Maryland.

    The Johns Hopkins University also offers the “Center for Talented Youth” program—a nonprofit organization dedicated to identifying and developing the talents of the most promising K-12 grade students worldwide. As part of the Johns Hopkins University, the “Center for Talented Youth” or CTY helps fulfill the university’s mission of preparing students to make significant future contributions to the world. The Johns Hopkins Digital Media Center (DMC) is a multimedia lab space as well as an equipment, technology and knowledge resource for students interested in exploring creative uses of emerging media and use of technology.

    In 2013, the Bloomberg Distinguished Professorships program was established by a $250 million gift from Michael Bloomberg. This program enables the university to recruit fifty researchers from around the world to joint appointments throughout the nine divisions and research centers. Each professor must be a leader in interdisciplinary research and be active in undergraduate education. Directed by Vice Provost for Research Denis Wirtz, there are currently thirty two Bloomberg Distinguished Professors at the university, including three Nobel Laureates, eight fellows of the American Association for the Advancement of Science (US), ten members of the American Academy of Arts and Sciences, and thirteen members of the National Academies.

     
  • richardmitnick 12:22 pm on July 5, 2021 Permalink | Reply
    Tags: "Astronomers discover an oversized black hole population in the star cluster Palomar 5", , , , , phys.org, University of Barcelona [Universitat de Barcelona](ES)   

    From University of Barcelona [Universitat de Barcelona](ES) via phys.org : “Astronomers discover an oversized black hole population in the star cluster Palomar 5” 

    From University of Barcelona [Universitat de Barcelona](ES)

    via

    phys.org

    July 5, 2021

    1
    Credit: CC0 Public Domain.

    Palomar 5 is a unique star cluster. In a paper published today in Nature Astronomy, an international team of astrophysicists led by the University of Barcelona show that distinguishing features of Palomar 5 are likely the result of an oversized black hole population of more than 100 of them in the center of the cluster.

    2

    “The number of black holes is roughly three times larger than expected from the number of stars in the cluster, and it means that more than 20% of the total cluster mass is made up of black holes. They each have a mass of about 20 times the mass of the Sun, and they formed in supernova explosions at the end of the lives of massive stars, when the cluster was still very young,” says Prof Mark Gieles, from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and lead author of the paper.

    Tidal streams are streams of stars that were ejected from disrupting star clusters or dwarf galaxies. In the last few years, nearly thirty thin streams have been discovered in the Milky Way halo. “We do not know how these streams form, but one idea is that they are disrupted star clusters. However, none of the recently discovered streams have a star cluster associated with them, hence we can not be sure. So, to understand how these streams formed, we need to study one with a stellar system associated with it. Palomar 5 is the only case, making it a Rosetta Stone for understanding stream formation and that is why we studied it in detail,” explains Gieles.

    The authors simulate the orbits and the evolution of each star from the formation of the cluster until the final dissolution. They varied the initial properties of the cluster until a good match with observations of the stream and the cluster was found. The team finds that Palomar 5 formed with a lower black hole fraction, but stars escaped more efficiently than black holes, such that the black hole fraction gradually increased. The black holes dynamically puffed up the cluster in gravitational slingshot interactions with stars, which led to even more escaping stars and the formation of the stream. Just before it completely dissolves—roughly a billion years from now—the cluster will consist entirely of black holes. “This work has helped us understand that even though the fluffy Palomar 5 cluster has the brightest and longest tails of any cluster in the Milky Way, it is not unique. Instead, we believe that many similarly puffed up, black hole-dominated clusters have already disintegrated in the Milky Way tides to form the recently discovered thin stellar streams,” says co-author Dr. Denis Erkal at the University of Surrey.

    Gieles says, “We have shown that the presence of a large black hole population may have been common in all the clusters that formed the streams.” This is important for our understanding of globular cluster formation, the initial masses of stars and the evolution of massive stars. This work also has important implications for gravitational waves. “It is believed that a large fraction of binary black hole mergers form in star clusters. A big unknown in this scenario is how many black holes there are in clusters, which is hard to constrain observationally because we can not see black holes. Our method gives us a way to learn how many BHs there are in a star cluster by looking at the stars they eject.'”, says Dr. Fabio Antonini from Cardiff University, a co-author of the paper.

    Palomar 5 is a globular cluster discovered in 1950 by Walter Baade. It is in the Serpens constellation at a distance of about 80,000 light-years, and it is one of the roughly 150 globular clusters that orbit around the Milky Way. It is older than 10 billion years, like most other globular clusters, meaning that it formed in the earliest phases of galaxy formation. It is about 10 times less massive and five times more extended than a typical globular cluster and in the final stages of dissolution.

    June 3, 2002

    Dr. Jakob Staude
    MPIA Public Information Office
    Phone: (+49) 6221-528-229
    Fax: (+49) 6221-528-246
    e-mail: staude@mpia.de

    Sky Survey Unveils Star Cluster Shredded By The Milky Way

    Albuquerque, N.M. — A team of astronomers from the Sloan Digital Sky Survey (SDSS) collaboration has discovered a spectacular stream of stellar debris emanating from a star cluster that is being torn apart by the Milky Way.

    Sloan Digital Sky Survey telescope (US) at Apache Point near Sunspot, New Mexico Altitude 2,788 meters (9,147 ft.)

    SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft).

    Dr. Michael Odenkirchen and Dr. Eva Grebel from the MPG Institute for Astronomy [MPG Institut für Astronomie](DE) in Heidelberg, Germany, are presenting these findings today at the American Astronomical Society (US) meeting in Albuquerque, New Mexico. The detection of this stream, the first of its kind, supports theorists’ view that star clusters get destroyed by the tidal forces of the Milky Way. Researchers say such extended streams of tidal debris provide a new way to determine the mass distribution of the dark matter halo of our Galaxy.

    The stars in the newly discovered stream are being torn from an ancient globular cluster named Palomar 5, which is located in the outer part of our Galaxy 75,000 light years away from the Sun. While typical globular clusters are massive, luminous concentrations of some hundred thousand stars, Palomar 5 by comparison looks faint and diffuse and contains only about ten thousand stars. This led astronomers to suspect that Palomar 5 might be a likely victim of the disruptive tides of the Milky Way. These “tides” arise because the Milky Way’s gravitational pull is stronger on the cluster’s near side than on the far side, thus tearing the cluster apart. However, the telltale debris from the disruption was difficult to find since it is hidden in a sea of foreground and background objects.

    Using data from the SDSS and a special filtering technique, Odenkirchen and his collaborators have succeeded in making the stream of debris from Palomar 5 directly visible. “The excellent homogeneity, resolution, depth, and multi-color information of the SDSS observations have allowed us to separate faint former members of Palomar 5 from contaminating field stars and background galaxies,” says Odenkirchen, who is a postdoctoral researcher at the MPIA.

    The SDSS is an international project that is creating a deep map of one quarter of the sky in five colors. The SDSS records objects up to 10 million times fainter than the faintest stars visible with the naked eye. The observations are carried out with a special wide-field camera on a dedicated 2.5-meter telescope at Apache Point Observatory, New Mexico. Team member Dr. Connie Rockosi of the University of Washington (US) was one of the builders of the camera.

    First direct evidence for the tidal disruption of Palomar 5 emerged two years ago from SDSS commissioning data that happened to include Palomar 5. Odenkirchen and collaborators were amazed to recover the characteristic S-shape signature of tidal debris from these data. “This was the first time that tidal tails of a star cluster were seen with convincing clarity”, says Grebel, an astronomer who leads the Galactic structure group at MPIA.

    Meanwhile the SDSS has scanned a much larger region on the sky. Analyzing the new data the researchers found that the two tails emanating from Palomar 5 extend over an arc of ten degrees on the sky. This vast area corresponds to 20 times the diameter of the full moon on the sky or to a length of 13,000 light years in space. “Remarkably, we now find more mass in the tails than in the remaining cluster. We expect to detect the stream over an even larger area as the survey progresses,” Odenkirchen said.

    The tails of Palomar~5 delineate the orbital path of this cluster and thus provide a unique opportunity to determine its motion around the Milky Way. “The motions of objects orbiting the Galactic halo are still poorly known. It normally takes decades to measure even only the instantaneous displacement of a globular cluster on the sky,” Grebel points out. “Finding additional coherent streams that extend over large portions of the sky we would be able to reconstruct Galactic orbits independent of a specific Galactic model,” says the MPIA’s Dr. Walter Dehnen, who carried out extensive numerical simulations on the disruption of Palomar~5. The researchers expect that the geometry and the velocities of those tidal streams will become important tools for determining the mass of the dark matter halo of the Milky Way.

    Together with the so-called Sagittarius stream, which emerges from a dwarf galaxy that is currently being accreted by the Milky Way, there are now two different examples of extended stream-like structures in the Galactic halo. Computer simulations suggest that globular clusters were much more numerous in the early days of the Milky Way, and that many of them have already been shredded by Galactic tides. As the survey proceeds the SDSS researchers will be able to test this prediction by searching for signs of tidal mass loss around other globular clusters. “The SDSS data base will ultimately allow us to estimate the total number of such streams,” says Professor Hans-Walter Rix, director of the MPIA. “This will clarify the role of tidal disruption in the build-up of the Galactic halo and provide a crucial test for galaxy formation models.

    The researchers participating in this work are Michael Odenkirchen, Eva Grebel, Walter Dehnen, and Hans-Walter Rix from the Max Planck Institute for Astronomy, Connie Rockosi of the University of Washington, Brian Yanny from DOE’s Fermi National Accelerator Laboratory (US), and Heidi Newberg from the Rensselaer Polytechnic Institute (US).
    The SDSS is a joint project of The University of Chicago (US), Fermilab, the Institute for Advanced Study (US), the Japan Participation Group, The Johns Hopkins University (US), DOE’s Los Alamos National Laboratory (US), the Max-Planck Institute for Astronomy (MPIA), the MPG Institute for Astrophysics [MPG Institut für Astrophysik](DE), New Mexico State University (US), Princeton University (US), the United States Naval Observatory, the University of Pittsburgh (US), and the University of Washington.
    Funding for the SDSS has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society.

    3
    Fig. 1: Color-coded map of the distribution of stars emerging from the star cluster Palomar 5 (white blob). The two long tidal tails (orange) contain 1.3 times the mass of the cluster and delineate its orbit around the Milky Way (yellow line).

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Welcome to the University of Barcelona [Universitat de Barcelona] (ES)

    The University of Barcelona is the most formidable public institution of higher education in Catalonia, catering to the needs of the greatest number of students and delivering the broadest and most comprehensive offering in higher educational courses. The UB is also the principal centre of university research in Spain and has become a European benchmark for research activity, both in terms of the number of research programmes it conducts and the excellence these have achieved.

    Its own history closely tied to the history of Barcelona and of Catalonia, our university combines the values of tradition with its position as an institution dedicated to innovation and teaching excellence: a university that is as outward-looking and cosmopolitan as the city from which it takes its name.

    Welcome to the University of Barcelona. We hope to see you very soon!

    The University of Barcelona [Universidad de Barcelona] is a public university located in the city of Barcelona, Catalonia in Spain. With 73 undergraduate programs, 273 graduate programs and 48 doctorate programs to over 63,000 students, UB is considered to be the best university in Spain in the QS World University Rankings of 2018, which ranked the university 156th overall in the world. In the 2016-2017 ranking of University Ranking by Academic Performance, UB is considered the best university in Spain and 45th university in the world. Also, according to the yearly ranking made by US News, it is the 81st-best university in the world, and the best university in Spain.

     
  • richardmitnick 9:57 pm on June 30, 2021 Permalink | Reply
    Tags: "A fast-expanding Type Ia supernova exploded in NGC 474 study finds", , , , , , phys.org, Xinglong Observatory [兴隆观测站] (CN)   

    From Xinglong Observatory [兴隆观测站] (CN) via phys.org : “A fast-expanding Type Ia supernova exploded in NGC 474, study finds” 

    LAMOST telescope located in Xinglong Station, Hebei Province, China.

    From Xinglong Observatory [兴隆观测站] (CN)

    Chinese Academy of Sciences [中国科学院] (CN)

    via

    phys.org

    June 30, 2021
    Tomasz Nowakowski

    1
    The left panel shows a color image which is synthesized from observations in gr bands obtained by the CFHT
    before the discovery of SN 2017fgc. The red circle marks the position of SN 2017fgc and the gas bridge can be clearly seen here. The right panel shows a color image synthesized from TNT observations in the gri bands after the explosion of SN 2017fgc, and the SN is marked with a red circle while the reference stars are labeled by numbers. Credit: Zeng et al., 2021.


    Using ground-based facilities, astronomers from China and elsewhere have conducted extensive optical photometric and spectroscopic observations of the supernova SN 2017fgc, which exploded in the galaxy NGC 474. Results of the study, published June 23, indicate that this explosion is a fast-expanding Type Ia supernova.

    Type Ia supernovae (SN Ia) are found in binary systems in which one of the stars is a white dwarf. Stellar explosions of this type are important for the scientific community, as they offer essential clues into the evolution of stars and galaxies.

    SN 2017fgc was detected on July 9, 2017 by the Distance Less Than 40 Mpc (DLT40) survey. Further studies of SN 2017fgc classified it as a normal supernova of Type Ia and found that it exploded in the nearby shell galaxy NGC 474 at a distance of some 96.2 million light years.

    Now, new observations of SN 2017fgc conducted by a team of astronomers led by Xiangyun Zeng of the Xinjiang Astronomical Observatory in China, shed more light on the properties of this SN. The team used a set of various observatories for their study, including the 0.8 m Tsinghua NAOC telescope (TNT).

    2
    Tsinghua NAOC telescope (TNT)

    The researchers monitored SN 2017fgc from 12 days before to around 389 days after its maximum brightness. The observations found that the SN has an absolute peak magnitude of about −19.32 mag and a post-peak decline at a level of 1.05 mag. Its peak luminosity was measured to be approximately 13.2 tredecillion erg/s, what indicates a synthesized nickel mass of about 0.51 solar masses.

    The spectral evolution of SN 2017fgc suggests that it is a high-velocity (HV) SN Ia. It was noted that it has a maximum-light Si II velocity of about 15,000 km/s and a post-peak velocity gradient at a level of some 120 km/s/d. Moreover, the light curve and color curve evolution of SN 2017fgc turned out to be similar to those of other fast-expanding HV SNe Ia such as SN 2002bo and SN 2006X.

    However, the study found that SN 2017fgc is located far away (about 61,600 light years) from the center of its host galaxy, while HV SNe Ia usually explode near the center of their hosts.

    “It seems that SN 2017fgc is an outlier and does not follow this trend of HV SNe Ia. However, closer inspection of the host galaxy NGC 474 reveals that it is a massive lenticular galaxy that experienced a merger ∼ 2 Gyr ago. (…) We speculate that SN 2017fgc could be ejected from the inner part of the companion galaxy NGC 470 during the merger that took place at ∼2 Gyr ago, or formed as a result of some cold gas remaining in the companion disk,” the astronomers write.

    They added that more observations, focused on the host environment of SN 2017fgc, are needed to confirm this assumption.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Chinese Academy of Sciences-National Astronomical Observatories Xinglong Observatory Station, located in Xinglong Station, Hebei Province, China.

    The Xinglong Observatory [兴隆观测站] (CN) of the National Astronomical Observatories, Chinese Academy of Sciences (NAOC) (IAU code: 327, coordinates: 40°23′39′′ N, 117°34′30′′ E) was founded in 1968. At present, it is one of most primary observing stations of NAOC. As the largest optical astronomical observatory site in the continent of Asia, it has 9 telescopes with effective aperture larger than 50 cm. These are the Guo Shoujing Telescope, also called the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), the 2.16-m Telescope, a 1.26-m optical & near-infrared telescope, a 1-m Alt-Az telescope, an 85-cm telescope (NAOC-Beijing Normal University Telescope, NBT), an 80-cm telescope (Tsinghua University-NAOC Telescope, TNT), a 60-cm telescope, a 50-cm telescope and a 60/90-cm Schmidt telescope.

    The average altitude of the Xinglong Observatory is about 900 m. The Xinglong Observatory is located at the south of the main peak of the Yanshan Mountains, in the Xinglong County, Hebei Province, which lies about 120 km (about 2 hours’ drive) to the northeast of Beijing. A shuttle bus runs between NAOC campus and Xinglong Observatory every Tuesday and Friday. The mean and media seeing values of the Xinglong Observatory are 1.9′′ and 1.7′′, respectively. On average, there are 117 photometric nights and 230 observable nights per year based on the data of 2007-2014. Most of the time, the wind speed is less than 4 m/s (the mean value is 2 m/s), and the sky brightness is about 21.1 mag arcsec2 in V band at the zenith.

    Each year, more than a hundred astronomers use the telescopes of the Xinglong Observatory to perform the observations for the studies on Galactic sciences (stellar parameters, extinction measurements, Galactic structures, exoplanets, etc.) and extragalactic sciences (including nearby galaxies, AGNs, high-redshift quasars), as well as time-domain astronomy (supernovae, gamma-ray bursts, stellar tidal disruption events, and different types of variable stars). In recent years, besides the basic daily maintenance of the telescopes, new techniques and methods have been explored by the engineers and technicians of the Xinglong Observatory to improve the efficiency of observations. Meanwhile, the Xinglong Observatory is also a National populscience and education base of China for training students from graduate schools, colleges, high schools and other education institutes throughout China, and it has hosted a number of international workshops and summer schools.

    The Chinese Academy of Sciences [中国科学院] (CN) is the linchpin of China’s drive to explore and harness high technology and the natural sciences for the benefit of China and the world. Comprising a comprehensive research and development network, a merit-based learned society and a system of higher education, CAS brings together scientists and engineers from China and around the world to address both theoretical and applied problems using world-class scientific and management approaches.

    Since its founding, CAS has fulfilled multiple roles — as a national team and a locomotive driving national technological innovation, a pioneer in supporting nationwide S&T development, a think tank delivering S&T advice and a community for training young S&T talent.

    Now, as it responds to a nationwide call to put innovation at the heart of China’s development, CAS has further defined its development strategy by emphasizing greater reliance on democratic management, openness and talent in the promotion of innovative research. With the adoption of its Innovation 2020 programme in 2011, the academy has committed to delivering breakthrough science and technology, higher caliber talent and superior scientific advice. As part of the programme, CAS has also requested that each of its institutes define its “strategic niche” — based on an overall analysis of the scientific progress and trends in their own fields both in China and abroad — in order to deploy resources more efficiently and innovate more collectively.

    As it builds on its proud record, CAS aims for a bright future as one of the world’s top S&T research and development organizations.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: