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  • richardmitnick 11:18 am on July 31, 2021 Permalink | Reply
    Tags: "Magnetic fields implicated in the mysterious midlife crisis of stars", , , , Royal Astronomical Society (UK),   

    From Royal Astronomical Society (UK) : “Magnetic fields implicated in the mysterious midlife crisis of stars” 

    From Royal Astronomical Society (UK)

    28/07/2021

    Media contacts

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

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

    Science contacts

    Prof. Dibyendu Nandy
    Center of Excellence in Space Sciences India & Department of Physical Sciences
    Indian Institute of Science Education and Research (IISER) Kolkata
    Tel: (+91) 9748 606 215
    dnandi@iiserkol.ac.in

    Bindesh Tripathi
    Graduate Research Assistant, Plasma Physics
    University of Wisconsin-Madison
    Tel: (+1) 6086 402 059
    btripathi@wisc.edu

    1
    Magnetic fields are produced by a dynamo mechanism inside stars and emerge through the surface to the outer atmosphere, where they generate stellar magnetic storms, energetic radiation fluxes, and govern the strength of escaping plasma winds. Studying these magnetic fields can shed light on the stellar midlife crisis – a sudden switch to a low activity phase and the existence of inactive phases such as the Maunder Minimum when hardly any sunspots are observed on the Sun. Credit: National Aeronautics Space Agency (US) /NASA Goddard Space Flight Center (US) / Solar Dynamics Observatory. Licence type Attribution (CC BY 4.0)

    Middle-aged stars can experience their own kind of midlife crisis, experiencing dramatic breaks in their activity and rotation rates at about the same age as our Sun, according to new research published today in MNRAS:Letters. The study provides a new theoretical underpinning for the unexplained breakdown of established techniques for measuring ages of stars past their middle age, and the transition of solar-like stars to a magnetically inactive future.

    Astronomers have long known that stars experience a process known as ‘magnetic braking’: a steady stream of charged particles, known as the solar wind, escapes from the star over time, carrying away small amounts of the star’s angular momentum. This slow drain causes stars like our Sun to gradually slow down their rotation over billions of years.

    In turn, the slower rotation leads to altered magnetic fields and less stellar activity – the numbers of sunspots, flares, outbursts, and similar phenomena in the atmospheres of stars, which are intrinsically linked to the strengths of their magnetic fields.

    This decrease in activity and rotation rate over time is expected to be smooth and predictable because of the gradual loss of angular momentum. The idea gave birth to the tool known as ‘stellar gyrochronology’, which has been widely used over the past two decades to estimate the age of a star from its rotation period.

    However recent observations indicate that this intimate relationship breaks down around middle age. The new work, carried out by Bindesh Tripathi, Prof. Dibyendu Nandy, and Prof. Soumitro Banerjee at the INDIAN INSTITUTE OF SCIENCE EDUCATION AND RESEARCH KOLKATA[भारतीय विज्ञान शिक्षा एवं अनुसंधान संस्थान कोलकाता] (IN), India, provides a novel explanation for this mysterious ailment.

    Using dynamo models of magnetic field generation in stars, the team show that at about the age of the Sun the magnetic field generation mechanism of stars suddenly becomes sub-critical or less efficient. This allows stars to exist in two distinct activity states – a low activity mode and an active mode. A middle aged star like the Sun can often switch to the low activity mode resulting in drastically reduced angular momentum losses by magnetized stellar winds.

    Prof. Nandy comments: “This hypothesis of sub-critical magnetic dynamos of solar-like stars provides a self-consistent, unifying physical basis for a diversity of solar-stellar phenomena, such as why stars beyond their midlife do not spin down as fast as in their youth, the breakdown of stellar gyrochronology relations, and recent findings suggesting that the Sun may be transitioning to a magnetically inactive future.”

    The new work provides key insights into the existence of low activity episodes in the recent history of the Sun known as grand minima – when hardly any sunspots are seen. The best known of these is perhaps the Maunder Minimum around 1645 to 1715, when very few sunspots were observed.

    The team hope that it will also shed light on recent observations indicating that the Sun is comparatively inactive, with crucial implications for the potential long-term future of our own stellar neighbour.

    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 6:03 am on July 21, 2021 Permalink | Reply
    Tags: "Tail without a comet-the dusty remains of Comet ATLAS", , , , , Royal Astronomical Society (UK),   

    From Royal Astronomical Society (UK) : “Tail without a comet-the dusty remains of Comet ATLAS” 

    From Royal Astronomical Society (UK)

    7.20.21

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

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

    Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243
    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 contact:
    Dr. Lorenzo Matteini
    Space and Atmospheric Physics group
    Imperial College London
    l.matteini@imperial.ac.uk

    A serendipitous flythrough of the tail of a disintegrated comet has offered scientists a unique opportunity to study these remarkable structures, in new research presented today at the National Astronomy Meeting 2021.

    3
    Hubble Space Telescope image of comet C/2019 Y4 (ATLAS), taken on April 20 2020, providing the sharpest view to date of the breakup of the solid nucleus of the comet. Hubble’s eagle-eye view identifies as many as 30 separate fragments, and distinguishes pieces that are roughly the size of a house. Before the breakup, the entire nucleus of the comet may have been the length of one or two football fields. The comet was approximately 91 million miles (146 million kilometres) from Earth when the image was taken. Credit: National Aeronautics Space Agency (US) / European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU) / Space Telescope Science Institute (US) / D. Jewitt (University of California-Los Angeles (US)). Licence type Attribution (CC BY 4.0)

    Comet ATLAS fragmented just before its closest approach to the Sun last year, leaving its former tail trailing through space in the form of wispy clouds of dust and charged particles. The disintegration was observed by the Hubble Space Telescope in April 2020 [see story below], but more recently the ESA spacecraft Solar Orbiter has flown close to the tail remnants in the course of its ongoing mission.
    ______________________________________________________________________________________________________________

    ESA-United Space for Europe

    European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU)
    “Solar Orbiter to pass through the tails of Comet ATLAS”
    29/05/2020

    ESA’s Solar Orbiter will cross through the tails of Comet ATLAS during the next few days. Although the recently launched spacecraft was not due to be taking science data at this time, mission experts have worked to ensure that the four most relevant instruments will be switched on during the unique encounter.

    Solar Orbiter was launched on 10 February 2020. Since then, and with the exception of a brief shutdown due to the coronavirus pandemic, scientists and engineers have been conducting a series of tests and set-up routines known as commissioning.

    The completion date for this phase was set at 15 June, so that the spacecraft could be fully functional for its first close pass of the Sun, or perihelion, in mid-June. However, the discovery of the chance encounter with the comet made things more urgent.

    Serendipitously flying through a comet’s tail is a rare event for a space mission, something scientists know to have happened only six times before for missions that were not specifically chasing comets. All such encounters have been discovered in the spacecraft data after the event. Solar Orbiter’s upcoming crossing is the first to be predicted in advance.

    It was noticed by Geraint Jones of the UCL Mullard Space Science Laboratory (UK), who has a 20-year history of investigating such encounters. He discovered the first accidental tail crossing in 2000, while investigating a strange disturbance in data recorded by the ESA/NASA Ulysses Sun-studying spacecraft in 1996. This study revealed that the spacecraft had passed through the tail of Comet Hyakutake, also known as ‘The Great Comet of 1996’. Soon after the announcement, Ulysses crossed the tail of another comet, and then a third one in 2007.

    Earlier this month, realising that Solar Orbiter was going to be 44 million kilometres downstream of Comet C/2019 Y4 (ATLAS) in just a matter of weeks, Geraint immediately alerted the ESA team.

    Solar Orbiter is equipped with a suite of 10 in-situ and remote-sensing instruments to investigate the Sun and the flow of charged particles it releases into space – the solar wind. Fortuitously, the four in-situ instruments are also perfect for detecting the comet’s tails because they measure the conditions around the spacecraft, and so they could return data about the dust grains and the electrically charged particles given off by the comet. These emissions create the comet’s two tails: the dust tail that is left behind in the comet’s orbit and the ion tail that points straight away from the Sun.

    Solar Orbiter will cross the ion tail of Comet ATLAS on 31 May–1 June, and the dust tail on 6 June. If the ion tail is dense enough, Solar Orbiter’s magnetometer (MAG) might detect the variation of the interplanetary magnetic field because of its interaction with ions in the comet’s tail, while the Solar Wind Analyser (SWA) could directly capture some of the tail particles.

    When Solar Orbiter crosses the dust tail, depending on its density – which is extremely difficult to predict – it is possible that one or more tiny dust grains may hit the spacecraft at speeds of tens of kilometres per second. While there is no significant risk to the spacecraft from this, the dust grains themselves will be vaporised on impact, forming tiny clouds of electrically charged gas, or plasma, which could be detected by the Radio and Plasma Waves (RPW) instrument.

    “An unexpected encounter like this provides a mission with unique opportunities and challenges, but that’s good! Chances like this are all part of the adventure of science,” says Günther Hasinger, ESA Director of Science.

    One of those challenges was that the instruments seemed unlikely to all be ready in time because of the commissioning. Now, thanks to a special effort by the instrument teams and ESA’s mission operations team, all four in-situ instruments will be on and collecting data, even though at certain times the instruments will need to be switched back into commissioning mode to ensure that the 15 June deadline is met.

    “With these caveats, we are ready for whatever Comet ATLAS has to tell us,” says Daniel Müller, ESA Project Scientist for Solar Orbiter.

    Expect the unexpected

    3
    Hubble captures breakup of Comet ATLAS in April 2020.

    Another challenge entails the comet’s behaviour. Comet ATLAS was discovered on 28 December 2019. During the next few months, it brightened so much that astronomers wondered whether it would become visible to the naked eye in May.

    Unfortunately, in early April the comet fragmented. As a result, its brightness dropped significantly too, robbing sky watchers of the view. A further fragmentation in mid-May has diminished the comet even more, making it less likely to be detectable by Solar Orbiter.

    Although the chances of detection have reduced, the effort is still worth making according to Geraint.

    “With each encounter with a comet, we learn more about these intriguing objects. If Solar Orbiter detects Comet ATLAS’s presence, then we’ll learn more about how comets interact with the solar wind, and we can check, for example, whether our expectations of dust tail behaviour agree with our models,” he explains. “All missions that encounter comets provide pieces of the jigsaw puzzle.”

    Geraint is the principal investigator of ESA’s future Comet Interceptor mission, which consists of three spacecraft and is scheduled for launch in 2028. It will make a much closer flyby of an as yet unknown comet that will be selected from the newly discovered comets nearer the time of launch (or even after that).

    Grazing the Sun

    4
    Solar Orbiter: journey around the Sun.

    Solar Orbiter is currently circling our parent star between the orbits of Venus and Mercury, with its first perihelion to take place on 15 June, around 77 million kilometres from the Sun. In coming years, it will get much closer, within the orbit of Mercury, around 42 million kilometres from the solar surface. Meanwhile, Comet ATLAS is already there, approaching its own perihelion, which is expected on 31 May, around 37 million kilometres from the Sun.

    “This tail crossing is also exciting because it will happen for the first time at such close distances from the Sun, with the comet nucleus being inside the orbit of Mercury,” says Yannis Zouganelis, ESA Deputy Project Scientist for Solar Orbiter.

    Understanding the dust environment in the innermost region of the Solar System is one of Solar Orbiter’s scientific objectives.

    “Near-Sun comets like Comet ATLAS are sources of dust in the inner heliosphere and so this study will not only help us understand the comet, but also the dust environment of our star,” adds Yannis.

    Looking at an icy object rather than the scorching Sun is certainly an exciting – and unexpected – way for Solar Orbiter to start its scientific mission, but that’s the nature of science.

    “Scientific discovery is built on good planning and serendipity. In the three months since launch, the Solar Orbiter team has already proved that it’s ready for both,” says Daniel.

    Science paper:
    Research Notes of the AAS

    See the full article here .
    ______________________________________________________________________________________________________________

    National Aeronautics and Space Administration(US)/European Space Agency [Agence spatiale européenne] [Europäische Weltraumorganisation] (EU) Hubble Space Telescope

    European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU)/National Aeronautics and Space Administration (US) Solar Orbiter

    His lucky encounter has presented researchers with a unique opportunity to investigate the structure of an isolated cometary tail. Using combined measurements from all of Solar Orbiter’s in-situ instruments, the scientists have reconstructed the encounter with ATLAS’s tail. The resulting model indicates that the ambient interplanetary magnetic field carried by the solar wind ‘drapes’ around the comet, and surrounds a central tail region with a weaker magnetic field.

    Comets are typically characterized by two separate tails; one is the well-known bright and curved dust tail, the other – typically fainter – is the ion tail. The ion tail originates from the interaction between the cometary gas and the surrounding solar wind, the hot gas of charged particles that constantly blows from the Sun and permeates the whole Solar System.

    When the solar wind interacts with a solid obstacle, like a comet, its magnetic field is thought to bend and ‘drape’ around it. The simultaneous presence of magnetic field draping and cometary ions released by the melting of the icy nucleus then produces the characteristic second ion tail, which can extend for large distances downstream from the comet’s nucleus.

    Lorenzo Matteini, a solar physicist at Imperial College London and leader of the work, says: “This is quite a unique event, and an exciting opportunity for us to study the makeup and structure of comet tails in unprecedented detail. Hopefully with the Parker Solar Probe and Solar Orbiter now orbiting the Sun closer than ever before, these events may become much more common in future!”

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

    This is the first comet tail detection occurring so close to the Sun – well inside the orbit of Venus. It is also one of the very few cases where scientists have been able to make direct measurements from a fragmented comet. Data from this encounter is expected to contribute greatly to our understanding of the interaction of comets with the solar wind and the structure and formation of their ion tails.

    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 4:56 pm on July 19, 2021 Permalink | Reply
    Tags: "Cosmic rays help supernovae explosions pack a bigger punch", , , , , Royal Astronomical Society (UK),   

    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 9:47 am on July 8, 2021 Permalink | Reply
    Tags: "Earth-like biospheres on other planets may be rare", , , , , Royal Astronomical Society (UK)   

    From Royal Astronomical Society (UK) : “Earth-like biospheres on other planets may be rare” 

    From Royal Astronomical Society

    7.8.21

    Media contacts

    Dr Robert Massey
    Royal Astronomical Society
    United Kingdom
    Tel: +44 (0)20 7292 3979
    Mob: +44 (0)7802 877 699
    press@ras.ac.uk

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

    Science contacts

    Prof. Giovanni Covone
    Università di Napoli Federico II
    Naples, Italy
    giovanni.covone@unina.it

    1
    An artistic representation of the potentially habitable planet Kepler 422-b (left), compared with Earth (right). Credit: Ph03nix1986 / Wikimedia Commons. Licence type Attribution-ShareAlike (CC BY-SA 4.0)

    A new analysis of known exoplanets has revealed that Earth-like conditions on potentially habitable planets may be much rarer than previously thought. The work focuses on the conditions required for oxygen-based photosynthesis to develop on a planet, which would enable complex biospheres of the type found on Earth. The study is published today in MNRAS.

    The number of confirmed planets in our own Milky Way galaxy now numbers into the thousands. However planets that are both Earth-like and in the habitable zone – the region around a star where the temperature is just right for liquid water to exist on the surface – are much less common.

    At the moment, only a handful of such rocky and potentially habitable exoplanets are known. However the new research indicates that none of these has the theoretical conditions to sustain an Earth-like biosphere by means of ‘oxygenic’ photosynthesis – the mechanism plants on Earth use to convert light and carbon dioxide into oxygen and nutrients.

    Only one of those planets comes close to receiving the stellar radiation necessary to sustain a large biosphere: Kepler−442b, a rocky planet about twice the mass of the Earth, orbiting a moderately hot star around 1,200 light years away.

    The study looked in detail at how much energy is received by a planet from its host star, and whether living organisms would be able to efficiently produce nutrients and molecular oxygen, both essential elements for complex life as we know it, via normal oxygenic photosynthesis.

    By calculating the amount of photosynthetically active radiation (PAR) that a planet receives from its star, the team discovered that stars around half the temperature of our Sun cannot sustain Earth-like biospheres because they do not provide enough energy in the correct wavelength range. Oxygenic photosynthesis would still be possible, but such planets could not sustain a rich biosphere.

    Planets around even cooler stars known as red dwarfs, which smoulder at roughly a third of our Sun’s temperature, could not receive enough energy to even activate photosynthesis. Stars that are hotter than our Sun are much brighter, and emit up to ten times more radiation in the necessary range for effective photosynthesis than red dwarfs, however generally do not live long enough for complex life to evolve.

    “Since red dwarfs are by far the most common type of star in our galaxy, this result indicates that Earth-like conditions on other planets may be much less common than we might hope,” comments Prof. Giovanni Covone of the University of Naples, lead author of the study.

    He adds: “This study puts strong constraints on the parameter space for complex life, so unfortunately it appears that the “sweet spot” for hosting a rich Earth-like biosphere is not so wide.”

    Future missions such as the James Webb Space Telescope (JWST), due for launch later this year, will have the sensitivity to look to distant worlds around other stars and shed new light on what it really takes for a planet to host life as we know it.

    See the full article here.

    See also from From University of Naples Federico II [Università degli Studi di Napoli Federico II] (IT) via EarthSky here.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Royal Astronomical Society (RAS)(UK) 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 RAS publishes the scientific journals MNRAS and Geophysical Journal International, along with the trade magazine Astronomy & Geophysics.

    The RAS 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.

    Publications

    One of the major activities of the RAS is publishing refereed journals. It publishes two primary research journals, the Monthly Notices of the Royal Astronomical Society in astronomy and (in association with the Deutsche Geophysikalische Gesellschaft) the Geophysical Journal International in geophysics. It also publishes the magazine A&G which includes reviews and other articles of wide scientific interest in a ‘glossy’ format. The full list of journals published (both currently and historically) by the RAS, with abbreviations as used for the NASA ADS bibliographic codes is:

    Memoirs of the Royal Astronomical Society (MmRAS): 1822–1977[3]
    Monthly Notices of the Royal Astronomical Society (MNRAS): Since 1827
    Geophysical Supplement to Monthly Notices (MNRAS): 1922–1957
    Geophysical Journal (GeoJ): 1958–1988
    Geophysical Journal International (GeoJI): Since 1989 (volume numbering continues from GeoJ)
    Quarterly Journal of the Royal Astronomical Society (QJRAS): 1960–1996
    Astronomy & Geophysics (A&G): Since 1997 (volume numbering continues from QJRAS)

    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 10:54 am on May 5, 2021 Permalink | Reply
    Tags: "Mysterious hydrogen-free supernova sheds light on stars’ violent death throes", , , , , , Royal Astronomical Society (UK)   

    From Royal Astronomical Society (UK) and Northwestern University(US) : “Mysterious hydrogen-free supernova sheds light on stars’ violent death throes” 

    From Royal Astronomical Society (UK)

    and

    Northwestern U bloc

    Northwestern University(US)

    Media contacts

    Amanda Morris
    Science and Engineering Editor
    Northwestern University
    United States
    Tel: +1 847 467 6790
    amandamo@northwestern.edu

    Morgan Hollis
    Deputy Press Officer
    Royal Astronomical Society
    United Kingdom
    Mob: +44 (0)7802 877 700
    press@ras.ac.uk

    Science contacts

    Charles Kilpatrick
    Center for Interdisciplinary Exploration and Research in Astrophysics
    Northwestern University
    United States
    ckilpatrick@northwestern.edu

    1
    Artist’s impression of a yellow supergiant in a close binary with a blue, main sequence companion star.
    Credit: Aya Tsuboi/Kavli IPMU (JP). Licence type Attribution (CC BY 4.0).

    A curiously yellow pre-supernova star has caused astrophysicists to re-evaluate what’s possible at the deaths of our Universe’s most massive stars. The team describe the peculiar star and its resulting supernova in a new study published today in MNRAS.

    At the end of their lives, cool, yellow stars are typically shrouded in hydrogen, which conceals the star’s hot, blue interior. But this yellow star, located 35 million light years from Earth in the Virgo galaxy cluster, was mysteriously lacking this crucial hydrogen layer at the time of its explosion.

    “We haven’t seen this scenario before,” said Charles Kilpatrick, postdoctoral fellow at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), who led the study. “If a star explodes without hydrogen, it should be extremely blue — really, really hot. It’s almost impossible for a star to be this cool without having hydrogen in its outer layer. We looked at every single stellar model that could explain a star like this, and every single model requires that the star had hydrogen, which, from its supernova, we know it did not. It stretches what’s physically possible.”

    Kilpatrick is also a member of the Young Supernova Experiment, which uses the Pan-STARRS telescope at Haleakalā, Hawaii to catch supernovae right after they explode.

    After the Young Supernova Experiment spotted supernova 2019yvr in the relatively nearby spiral galaxy NGC 4666, the team used deep space images captured by NASA’s Hubble Space Telescope, which fortunately already observed this section of the sky two and a half years before the star exploded.

    “What massive stars do right before they explode is a big unsolved mystery,” Kilpatrick said. “It’s rare to see this kind of star right before it explodes into a supernova.”

    The Hubble images show the source of the supernova, a massive star imaged just a couple of years before the explosion. Several months after the explosion however, Kilpatrick and his team discovered that the material ejected in the star’s final explosion seemed to collide with a large mass of hydrogen. This led the team to hypothesize that the progenitor star might have expelled the hydrogen within a few years before its death.

    “Astronomers have suspected that stars undergo violent eruptions or death throes in the years before we see supernovae,” Kilpatrick said. “This star’s discovery provides some of the most direct evidence ever found that stars experience catastrophic eruptions, which cause them to lose mass before an explosion. If the star was having these eruptions, then it likely expelled its hydrogen several decades before it exploded.”

    In the new study, Kilpatrick’s team also presents another possibility: a less massive companion star might have stripped away hydrogen from the supernova’s progenitor star. However, the team will not be able to search for the companion star until after the supernova’s brightness fades, which could take up to a decade.

    “Unlike its normal behaviour right after it exploded, the hydrogen interaction revealed it’s kind of this oddball supernova,” Kilpatrick said. “But it’s exceptional that we were able to find its progenitor star in Hubble data. In four or five years, I think we will be able to learn more about what happened.”

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Northwestern South Campus
    South Campus

    Northwestern University(US) is a private research university in Evanston, Illinois. Founded in 1851 to serve the former Northwest Territory, the university is a founding member of the Big Ten Conference.

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is known for its focus on interdisciplinary education, extensive research output, and student traditions. The university provides instruction in over 200 formal academic concentrations, including various dual degree programs. The university is composed of eleven undergraduate, graduate, and professional schools, which include the Kellogg School of Management, the Pritzker School of Law, the Feinberg School of Medicine, the Weinberg College of Arts and Sciences, the Bienen School of Music, the McCormick School of Engineering and Applied Science, the Medill School of Journalism, the School of Communication, the School of Professional Studies, the School of Education and Social Policy, and The Graduate School. As of fall 2019, the university had 21,946 enrolled students, including 8,327 undergraduates and 13,619 graduate students.

    Valued at $12.2 billion, Northwestern’s endowment is among the largest university endowments in the United States. Its numerous research programs bring in nearly $900 million in sponsored research each year.

    Northwestern’s main 240-acre (97 ha) campus lies along the shores of Lake Michigan in Evanston, 12 miles north of Downtown Chicago. The university’s law, medical, and professional schools, along with its nationally ranked Northwestern Memorial Hospital, are located on a 25-acre (10 ha) campus in Chicago’s Streeterville neighborhood. The university also maintains a campus in Doha, Qatar and locations in San Francisco, California, Washington, D.C. and Miami, Florida.

    As of October 2020, Northwestern’s faculty and alumni have included 1 Fields Medalist, 22 Nobel Prize laureates, 40 Pulitzer Prize winners, 6 MacArthur Fellows, 17 Rhodes Scholars, 27 Marshall Scholars, 23 National Medal of Science winners, 11 National Humanities Medal recipients, 84 members of the American Academy of Arts and Sciences, 10 living billionaires, 16 Olympic medalists, and 2 U.S. Supreme Court Justices. Northwestern alumni have founded notable companies and organizations such as the Mayo Clinic, The Blackstone Group, Kirkland & Ellis, U.S. Steel, Guggenheim Partners, Accenture, Aon Corporation, AQR Capital, Booz Allen Hamilton, and Melvin Capital.

    The foundation of Northwestern University can be traced to a meeting on May 31, 1850, of nine prominent Chicago businessmen, Methodist leaders, and attorneys who had formed the idea of establishing a university to serve what had been known from 1787 to 1803 as the Northwest Territory. On January 28, 1851, the Illinois General Assembly granted a charter to the Trustees of the North-Western University, making it the first chartered university in Illinois. The school’s nine founders, all of whom were Methodists (three of them ministers), knelt in prayer and worship before launching their first organizational meeting. Although they affiliated the university with the Methodist Episcopal Church, they favored a non-sectarian admissions policy, believing that Northwestern should serve all people in the newly developing territory by bettering the economy in Evanston.

    John Evans, for whom Evanston is named, bought 379 acres (153 ha) of land along Lake Michigan in 1853, and Philo Judson developed plans for what would become the city of Evanston, Illinois. The first building, Old College, opened on November 5, 1855. To raise funds for its construction, Northwestern sold $100 “perpetual scholarships” entitling the purchaser and his heirs to free tuition. Another building, University Hall, was built in 1869 of the same Joliet limestone as the Chicago Water Tower, also built in 1869, one of the few buildings in the heart of Chicago to survive the Great Chicago Fire of 1871. In 1873 the Evanston College for Ladies merged with Northwestern, and Frances Willard, who later gained fame as a suffragette and as one of the founders of the Woman’s Christian Temperance Union (WCTU), became the school’s first dean of women (Willard Residential College, built in 1938, honors her name). Northwestern admitted its first female students in 1869, and the first woman was graduated in 1874.

    Northwestern fielded its first intercollegiate football team in 1882, later becoming a founding member of the Big Ten Conference. In the 1870s and 1880s, Northwestern affiliated itself with already existing schools of law, medicine, and dentistry in Chicago. Northwestern University Pritzker School of Law is the oldest law school in Chicago. As the university’s enrollments grew, these professional schools were integrated with the undergraduate college in Evanston; the result was a modern research university combining professional, graduate, and undergraduate programs, which gave equal weight to teaching and research. By the turn of the century, Northwestern had grown in stature to become the third largest university in the United States after Harvard University(US) and the University of Michigan(US).

    Under Walter Dill Scott’s presidency from 1920 to 1939, Northwestern began construction of an integrated campus in Chicago designed by James Gamble Rogers, noted for his design of the Yale University(US) campus, to house the professional schools. The university also established the Kellogg School of Management and built several prominent buildings on the Evanston campus, including Dyche Stadium, now named Ryan Field, and Deering Library among others. In the 1920s, Northwestern became one of the first six universities in the United States to establish a Naval Reserve Officers Training Corps (NROTC). In 1939, Northwestern hosted the first-ever NCAA Men’s Division I Basketball Championship game in the original Patten Gymnasium, which was later demolished and relocated farther north, along with the Dearborn Observatory, to make room for the Technological Institute.

    After the golden years of the 1920s, the Great Depression in the United States (1929–1941) had a severe impact on the university’s finances. Its annual income dropped 25 percent from $4.8 million in 1930-31 to $3.6 million in 1933-34. Investment income shrank, fewer people could pay full tuition, and annual giving from alumni and philanthropists fell from $870,000 in 1932 to a low of $331,000 in 1935. The university responded with two salary cuts of 10 percent each for all employees. It imposed hiring and building freezes and slashed appropriations for maintenance, books, and research. Having had a balanced budget in 1930-31, the university now faced deficits of roughly $100,000 for the next four years. Enrollments fell in most schools, with law and music suffering the biggest declines. However, the movement toward state certification of school teachers prompted Northwestern to start a new graduate program in education, thereby bringing in new students and much needed income. In June 1933, Robert Maynard Hutchins, president of the University of Chicago(US), proposed a merger of the two universities, estimating annual savings of $1.7 million. The two presidents were enthusiastic, and the faculty liked the idea; many Northwestern alumni, however, opposed it, fearing the loss of their Alma Mater and its many traditions that distinguished Northwestern from Chicago. The medical school, for example, was oriented toward training practitioners, and alumni feared it would lose its mission if it were merged into the more research-oriented University of Chicago Medical School. The merger plan was ultimately dropped. In 1935, the Deering family rescued the university budget with an unrestricted gift of $6 million, bringing the budget up to $5.4 million in 1938-39. This allowed many of the previous spending cuts to be restored, including half of the salary reductions.

    Like other American research universities, Northwestern was transformed by World War II (1939–1945). Regular enrollment fell dramatically, but the school opened high-intensity, short-term programs that trained over 50,000 military personnel, including future president John F. Kennedy. Northwestern’s existing NROTC program proved to be a boon to the university as it trained over 36,000 sailors over the course of the war, leading Northwestern to be called the “Annapolis of the Midwest.” Franklyn B. Snyder led the university from 1939 to 1949, and after the war, surging enrollments under the G.I. Bill drove dramatic expansion of both campuses. In 1948, prominent anthropologist Melville J. Herskovits founded the Program of African Studies at Northwestern, the first center of its kind at an American academic institution. J. Roscoe Miller’s tenure as president from 1949 to 1970 saw an expansion of the Evanston campus, with the construction of the Lakefill on Lake Michigan, growth of the faculty and new academic programs, and polarizing Vietnam-era student protests. In 1978, the first and second Unabomber attacks occurred at Northwestern University. Relations between Evanston and Northwestern became strained throughout much of the post-war era because of episodes of disruptive student activism, disputes over municipal zoning, building codes, and law enforcement, as well as restrictions on the sale of alcohol near campus until 1972. Northwestern’s exemption from state and municipal property-tax obligations under its original charter has historically been a source of town-and-gown tension.

    Although government support for universities declined in the 1970s and 1980s, President Arnold R. Weber was able to stabilize university finances, leading to a revitalization of its campuses. As admissions to colleges and universities grew increasingly competitive in the 1990s and 2000s, President Henry S. Bienen’s tenure saw a notable increase in the number and quality of undergraduate applicants, continued expansion of the facilities and faculty, and renewed athletic competitiveness. In 1999, Northwestern student journalists uncovered information exonerating Illinois death-row inmate Anthony Porter two days before his scheduled execution. The Innocence Project has since exonerated 10 more men. On January 11, 2003, in a speech at Northwestern School of Law’s Lincoln Hall, then Governor of Illinois George Ryan announced that he would commute the sentences of more than 150 death-row inmates.

    In the 2010s, a 5-year capital campaign resulted in a new music center, a replacement building for the business school, and a $270 million athletic complex. In 2014, President Barack Obama delivered a seminal economics speech at the Evanston campus.

    Organization and administration

    Governance

    Northwestern is privately owned and governed by an appointed Board of Trustees, which is composed of 70 members and, as of 2011, has been chaired by William A. Osborn ’69. The board delegates its power to an elected president who serves as the chief executive officer of the university. Northwestern has had sixteen presidents in its history (excluding interim presidents). The current president, economist Morton O. Schapiro, succeeded Henry Bienen whose 14-year tenure ended on August 31, 2009. The president maintains a staff of vice presidents, directors, and other assistants for administrative, financial, faculty, and student matters. Kathleen Haggerty assumed the role of interim provost for the university in April 2020.

    Students are formally involved in the university’s administration through the Associated Student Government, elected representatives of the undergraduate students, and the Graduate Student Association, which represents the university’s graduate students.

    The admission requirements, degree requirements, courses of study, and disciplinary and degree recommendations for each of Northwestern’s 12 schools are determined by the voting members of that school’s faculty (assistant professor and above).

    Undergraduate and graduate schools

    Evanston Campus:

    Weinberg College of Arts and Sciences (1851)
    School of Communication (1878)
    Bienen School of Music (1895)
    McCormick School of Engineering and Applied Science (1909)
    Medill School of Journalism (1921)
    School of Education and Social Policy (1926)
    School of Professional Studies (1933)

    Graduate and professional

    Evanston Campus

    Kellogg School of Management (1908)
    The Graduate School

    Chicago Campus

    Feinberg School of Medicine (1859)
    Kellogg School of Management (1908)
    Pritzker School of Law (1859)
    School of Professional Studies (1933)

    Northwestern University had a dental school from 1891 to May 31, 2001, when it closed.

    Endowment

    In 1996, Princess Diana made a trip to Evanston to raise money for the university hospital’s Robert H. Lurie Comprehensive Cancer Center at the invitation of then President Bienen. Her visit raised a total of $1.5 million for cancer research.

    In 2003, Northwestern finished a five-year capital campaign that raised $1.55 billion, exceeding its fundraising goal by $550 million.

    In 2014, Northwestern launched the “We Will” campaign with a fundraising goal of $3.75 billion. As of December 31, 2019, the university has received $4.78 billion from 164,026 donors.

    Sustainability

    In January 2009, the Green Power Partnership (sponsored by the EPA) listed Northwestern as one of the top 10 universities in the country in purchasing energy from renewable sources. The university matches 74 million kilowatt hours (kWh) of its annual energy use with Green-e Certified Renewable Energy Certificates (RECs). This green power commitment represents 30 percent of the university’s total annual electricity use and places Northwestern in the EPA’s Green Power Leadership Club. The Initiative for Sustainability and Energy at Northwestern (ISEN), supporting research, teaching and outreach in these themes, was launched in 2008.

    Northwestern requires that all new buildings be LEED-certified. Silverman Hall on the Evanston campus was awarded Gold LEED Certification in 2010; Wieboldt Hall on the Chicago campus was awarded Gold LEED Certification in 2007, and the Ford Motor Company Engineering Design Center on the Evanston campus was awarded Silver LEED Certification in 2006. New construction and renovation projects will be designed to provide at least a 20% improvement over energy code requirements where feasible. At the beginning of the 2008–09 academic year, the university also released the Evanston Campus Framework Plan, which outlines plans for future development of the university’s Evanston campus. The plan not only emphasizes sustainable building construction, but also focuses on reducing the energy costs of transportation by optimizing pedestrian and bicycle access. Northwestern has had a comprehensive recycling program in place since 1990. The university recycles over 1,500 tons of waste, or 30% of all waste produced on campus, each year. All landscape waste at the university is composted.

    Academics

    Education and rankings

    Northwestern is a large, residential research university, and is frequently ranked among the top universities in the United States. The university is a leading institution in the fields of materials engineering, chemistry, business, economics, education, journalism, and communications. It is also prominent in law and medicine. Accredited by the Higher Learning Commission and the respective national professional organizations for chemistry, psychology, business, education, journalism, music, engineering, law, and medicine, the university offers 124 undergraduate programs and 145 graduate and professional programs. Northwestern conferred 2,190 bachelor’s degrees, 3,272 master’s degrees, 565 doctoral degrees, and 444 professional degrees in 2012–2013. Since 1951, Northwestern has awarded 520 honorary degrees. Northwestern also has chapters of academic honor societies such as Phi Beta Kappa (Alpha of Illinois), Eta Kappa Nu, Tau Beta Pi, Eta Sigma Phi (Beta Chapter), Lambda Pi Eta, and Alpha Sigma Lambda (Alpha Chapter).

    The four-year, full-time undergraduate program comprises the majority of enrollments at the university. Although there is no university-wide core curriculum, a foundation in the liberal arts and sciences is required for all majors; individual degree requirements are set by the faculty of each school. The university heavily emphasizes interdisciplinary learning, with 72% of undergrads combining two or more areas of study. Northwestern’s full-time undergraduate and graduate programs operate on an approximately 10-week academic quarter system with the academic year beginning in late September and ending in early June. Undergraduates typically take four courses each quarter and twelve courses in an academic year and are required to complete at least twelve quarters on campus to graduate. Northwestern offers honors, accelerated, and joint degree programs in medicine, science, mathematics, engineering, and journalism. The comprehensive doctoral graduate program has high coexistence with undergraduate programs.

    Despite being a mid-sized university, Northwestern maintains a relatively low student to faculty ratio of 6:1.

    Research

    Northwestern was elected to the Association of American Universities (US) in 1917 and is classified as an R1 university, denoting “very high” research activity. Northwestern’s schools of management, engineering, and communication are among the most academically productive in the nation. The university received $887.3 million in research funding in 2019 and houses over 90 school-based and 40 university-wide research institutes and centers. Northwestern also supports nearly 1,500 research laboratories across two campuses, predominately in the medical and biological sciences.

    Northwestern is home to the Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern Institute for Complex Systems, Nanoscale Science and Engineering Center, Materials Research Center, Center for Quantum Devices, Institute for Policy Research, International Institute for Nanotechnology, Center for Catalysis and Surface Science, Buffet Center for International and Comparative Studies, the Initiative for Sustainability and Energy at Northwestern, and the Argonne/Northwestern Solar Energy Research Center among other centers for interdisciplinary research.

    Student body

    Northwestern enrolled 8,186 full-time undergraduate, 9,904 full-time graduate, and 3,856 part-time students in the 2019–2020 academic year. The freshman retention rate for that year was 98%. 86% of students graduated after four years and 92% graduated after five years. These numbers can largely be attributed to the university’s various specialized degree programs, such as those that allow students to earn master’s degrees with a one or two year extension of their undergraduate program.

    The undergraduate population is drawn from all 50 states and over 75 foreign countries. 20% of students in the Class of 2024 were Pell Grant recipients and 12.56% were first-generation college students. Northwestern also enrolls the 9th-most National Merit Scholars of any university in the nation.

    In Fall 2014, 40.6% of undergraduate students were enrolled in the Weinberg College of Arts and Sciences, 21.3% in the McCormick School of Engineering and Applied Science, 14.3% in the School of Communication, 11.7% in the Medill School of Journalism, 5.7% in the Bienen School of Music, and 6.4% in the School of Education and Social Policy. The five most commonly awarded undergraduate degrees are economics, journalism, communication studies, psychology, and political science. The Kellogg School of Management’s MBA, the School of Law’s JD, and the Feinberg School of Medicine’s MD are the three largest professional degree programs by enrollment. With 2,446 students enrolled in science, engineering, and health fields, the largest graduate programs by enrollment include chemistry, integrated biology, material sciences, electrical and computer engineering, neuroscience, and economics.

    Athletics

    Northwestern is a charter member of the Big Ten Conference. It is the conference’s only private university and possesses the smallest undergraduate enrollment (the next-smallest member, the University of Iowa, is roughly three times as large, with almost 22,000 undergraduates).

    Northwestern fields 19 intercollegiate athletic teams (8 men’s and 11 women’s) in addition to numerous club sports. 12 of Northwestern’s varsity programs have had NCAA or bowl postseason appearances. Northwestern is one of five private AAU members to compete in NCAA Power Five conferences (the other four being Duke, Stanford, USC, and Vanderbilt) and maintains a 98% NCAA Graduation Success Rate, the highest among Football Bowl Subdivision schools.

    In 2018, the school opened the Walter Athletics Center, a $270 million state of the art lakefront facility for its athletics teams.

    Nickname and mascot

    Before 1924, Northwestern teams were known as “The Purple” and unofficially as “The Fighting Methodists.” The name Wildcats was bestowed upon the university in 1924 by Wallace Abbey, a writer for the Chicago Daily Tribune, who wrote that even in a loss to the University of Chicago, “Football players had not come down from Evanston; wildcats would be a name better suited to “[Coach Glenn] Thistletwaite’s boys.” The name was so popular that university board members made “Wildcats” the official nickname just months later. In 1972, the student body voted to change the official nickname to “Purple Haze,” but the new name never stuck.

    The mascot of Northwestern Athletics is “Willie the Wildcat”. Prior to Willie, the team mascot had been a live, caged bear cub from the Lincoln Park Zoo named Furpaw, who was brought to the playing field on game days to greet the fans. After a losing season however, the team decided that Furpaw was to blame for its misfortune and decided to select a new mascot. “Willie the Wildcat” made his debut in 1933, first as a logo and then in three dimensions in 1947, when members of the Alpha Delta fraternity dressed as wildcats during a Homecoming Parade.

    Traditions

    Northwestern’s official motto, “Quaecumque sunt vera,” was adopted by the university in 1890. The Latin phrase translates to “Whatsoever things are true” and comes from the Epistle of Paul to the Philippians (Philippians 4:8), in which St. Paul admonishes the Christians in the Greek city of Philippi. In addition to this motto, the university crest features a Greek phrase taken from the Gospel of John inscribed on the pages of an open book, ήρης χάριτος και αληθείας or “the word full of grace and truth” (John 1:14).
    Alma Mater is the Northwestern Hymn. The original Latin version of the hymn was written in 1907 by Peter Christian Lutkin, the first dean of the School of Music from 1883 to 1931. In 1953, then Director-of-Bands John Paynter recruited an undergraduate music student, Thomas Tyra (’54), to write an English version of the song, which today is performed by the Marching Band during halftime at Wildcat football games and by the orchestra during ceremonies and other special occasions.
    Purple became Northwestern’s official color in 1892, replacing black and gold after a university committee concluded that too many other universities had used these colors. Today, Northwestern’s official color is purple, although white is something of an official color as well, being mentioned in both the university’s earliest song, Alma Mater (1907) (“Hail to purple, hail to white”) and in many university guidelines.
    The Rock, a 6-foot high quartzite boulder donated by the Class of 1902, originally served as a water fountain. It was painted over by students in the 1940s as a prank and has since become a popular vehicle of self-expression on campus.
    Armadillo Day, commonly known as Dillo Day, is the largest student-run music festival in the country. The festival is hosted every Spring on Northwestern’s Lakefront.
    Primal Scream is held every quarter at 9 p.m. on the Sunday before finals week. Students lean out of windows or gather in courtyards and scream to help relieve stress.
    In the past, students would throw marshmallows during football games, but this tradition has since been discontinued.

    Philanthropy

    One of Northwestern’s most notable student charity events is Dance Marathon, the most established and largest student-run philanthropy in the nation. The annual 30-hour event is among the most widely-attended events on campus. It has raised over $1 million for charity ever year since 2011 and has donated a total of $13 million to children’s charities since its conception.

    The Northwestern Community Development Corps (NCDC) is a student-run organization that connects hundreds of student volunteers to community development projects in Evanston and Chicago throughout the year. The group also holds a number of annual community events, including Project Pumpkin, a Halloween celebration that provides over 800 local children with carnival events and a safe venue to trick-or-treat each year.

    Many Northwestern students participate in the Freshman Urban Program, an initiative for students interested in community service to work on addressing social issues facing the city of Chicago, and the university’s Global Engagement Studies Institute (GESI) programs, including group service-learning expeditions in Asia, Africa, or Latin America in conjunction with the Foundation for Sustainable Development.

    Several internationally recognized non-profit organizations were established at Northwestern, including the World Health Imaging, Informatics and Telemedicine Alliance, a spin-off from an engineering student’s honors thesis.

    Media

    Print

    Established in 1881, The Daily Northwestern is the university’s main student newspaper and is published on weekdays during the academic year. It is directed entirely by undergraduate students and owned by the Students Publishing Company. Although it serves the Northwestern community, the Daily has no business ties to the university and is supported wholly by advertisers.
    North by Northwestern is an online undergraduate magazine established in September 2006 by students at the Medill School of Journalism. Published on weekdays, it consists of updates on news stories and special events throughout the year. It also publishes a quarterly print magazine.
    Syllabus is the university’s undergraduate yearbook. It is distributed in late May and features a culmination of the year’s events at Northwestern. First published in 1885, the yearbook is published by Students Publishing Company and edited by Northwestern students.
    Northwestern Flipside is an undergraduate satirical magazine. Founded in 2009, it publishes a weekly issue both in print and online.
    Helicon is the university’s undergraduate literary magazine. Established in 1979, it is published twice a year: a web issue is released in the winter and a print issue with a web complement is released in the spring.
    The Protest is Northwestern’s quarterly social justice magazine.
    The Northwestern division of Student Multicultural Affairs supports a number of publications for particular cultural groups including Ahora, a magazine about Hispanic and Latino/a culture and campus life; Al Bayan, published by the Northwestern Muslim-cultural Student Association; BlackBoard Magazine, a magazine centered around African-American student life; and NUAsian, a magazine and blog on Asian and Asian-American culture and issues.
    The Northwestern University Law Review is a scholarly legal publication and student organization at Northwestern University School of Law. Its primary purpose is to publish a journal of broad legal scholarship. The Law Review publishes six issues each year. Student editors make the editorial and organizational decisions and select articles submitted by professors, judges, and practitioners, as well as student pieces. The Law Review also publishes scholarly pieces weekly on the Colloquy.
    The Northwestern Journal of Technology and Intellectual Property is a law review published by an independent student organization at Northwestern University School of Law.
    The Northwestern Interdisciplinary Law Review is a scholarly legal publication published annually by an editorial board of Northwestern undergraduates. Its mission is to publish interdisciplinary legal research, drawing from fields such as history, literature, economics, philosophy, and art. Founded in 2008, the journal features articles by professors, law students, practitioners, and undergraduates. It is funded by the Buffett Center for International and Comparative Studies and the Office of the Provost.

    Web-based

    Established in January 2011, Sherman Ave is a humor website that often publishes content on Northwestern student life. Most of its staff writers are current Northwestern undergraduates writing under various pseudonyms. The website is popular among students for its interviews of prominent campus figures, Freshman Guide, and live-tweeting coverage of football games. In Fall 2012, the website promoted a satiric campaign to end the Vanderbilt University football team’s custom of clubbing baby seals.
    Politics & Policy is dedicated to the analysis of current events and public policy. Established in 2010 by students at the Weinberg College of Arts and Sciences, School of Communication, and Medill School of Journalism, the publication reaches students on more than 250 college campuses around the world. Run entirely by undergraduates, it is published several times a week and features material ranging from short summaries of events to extended research pieces. The publication is financed in part by the Buffett Center.
    Northwestern Business Review is a campus source for business news. Founded in 2005, it has an online presence as well as a quarterly print schedule.
    TriQuarterly Online (formerly TriQuarterly) is a literary magazine published twice a year featuring poetry, fiction, nonfiction, drama, literary essays, reviews, blog posts, and art.
    The Queer Reader is Northwestern’s first radical feminist and LGBTQ+ publication.

    Radio, film, and television

    WNUR (89.3 FM) is a 7,200-watt radio station that broadcasts to the city of Chicago and its northern suburbs. WNUR’s programming consists of music (jazz, classical, and rock), literature, politics, current events, varsity sports (football, men’s and women’s basketball, baseball, softball, and women’s lacrosse), and breaking news on weekdays.
    Studio 22 is a student-run production company that produces roughly ten films each year. The organization financed the first film Zach Braff directed, and many of its films have featured students who would later go into professional acting, including Zach Gilford of Friday Night Lights.
    Applause for a Cause is currently the only student-run production company in the nation to create feature-length films for charity. It was founded in 2010 and has raised over $5,000 to date for various local and national organizations across the United States.
    Northwestern News Network is a student television news and sports network, serving the Northwestern and Evanston communities. Its studios and newsroom are located on the fourth floor of the McCormick Tribune Center on Northwestern’s Evanston campus. NNN is funded by the Medill School of Journalism.

    The Royal Astronomical Society (UK) , founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,400 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

    The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

    In 2020 the RAS is 200 years old. The Society is celebrating its bicentennial anniversary with a series of events around the UK, including public lectures, exhibitions, an organ recital, a pop-up planetarium, and the culmination of the RAS 200: Sky & Earth project.

     
  • richardmitnick 9:56 am on February 11, 2021 Permalink | Reply
    Tags: "Spectacular ‘honeycomb heart’ revealed in iconic stellar explosion", , , , , , Royal Astronomical Society (UK), The Crab Supernova Remnant   

    From Royal Astronomical Society (UK): “Spectacular ‘honeycomb heart’ revealed in iconic stellar explosion” 

    From Royal Astronomical Society (UK)

    09/02/2021

    Media contacts

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

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

    Science contacts

    Dr Thomas Martin
    Université Laval
    Quebec City (CN)
    thomas.martin.1@ulaval.ca

    Dr Dan Milisavljevic
    Purdue University
    Indiana (US)
    dmilisav@purdue.edu

    Dr Laurent Drissen
    Université Laval
    Quebec City (CN)
    ldrissen@phy.ulaval.ca

    1
    3D reconstruction of the Crab nebula remnant as seen from Earth (right), and from another point of view showing its heart-shaped morphology (left). Credit: Thomas Martin, Danny Milisavljevic and Laurent Drissen. Licence type: Attribution (CC BY 4.0).

    A unique ‘heart-shape’, with wisps of gas filaments showing an intricate honeycomb-like arrangement, has been discovered at the centre of the iconic supernova remnant, the Crab Nebula. Astronomers have mapped the void in unprecedented detail, creating a realistic three-dimensional reconstruction. The new work is published in MNRAS .

    The Crab, formally known as Messier 1, exploded as a dramatic supernova in 1054 CE, and was observed over the subsequent months and years by ancient astronomers across the world. The resulting nebula – the remnant of this enormous explosion – has been studied by amateur and professional astronomers for centuries. However, despite this rich history of investigation, many questions remain about what type of star was originally there and how the original explosion took place.

    Thomas Martin, the researcher at Université Laval (CA) who led the study, hopes to answer these questions using a new 3D reconstruction of the nebula. “Astronomers will now be able to move around and inside the Crab Nebula and study its filaments one by one,” said Martin.

    The team used the powerful SITELLE imaging spectrometer on the Canada-Hawaii-France Telescope (CFHT) in Mauna Kea, Hawaii (US), to compare the 3D shape of the Crab to two other supernova remnants.

    CFHT Sitelle optical imaging Fourier transform spectrometer (IFTS).


    CFHT Telescope, Maunakea, Hawaii, USA, at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level.

    Mauna Kea Observatory, Hawaii USA, altitude 4,213 m (13,822 ft).

    Remarkably, they found that all three remnants had ejecta arranged in large-scale rings, suggesting a history of turbulent mixing and radioactive plumes expanding from a collapsed iron core.

    Co-author Dan Milisavljevic, an assistant professor at Purdue University and supernova expert, concludes that the fascinating morphology of the Crab seems to go against the most popular explanation of the original explosion.

    “The Crab is often understood as being the result of an electron-capture supernova triggered by the collapse of an oxygen-neon-magnesium core, but the observed honeycomb structure may not be consistent with this scenario,” Milisavljevic said.

    The new reconstruction was made possible by the ground-breaking technology used by SITELLE, which incorporates a Michelson interferometer design allowing scientists to obtain over 300,000 high-resolution spectra of every single point of the nebula.

    “SITELLE was designed with objects like the Crab Nebula in mind; but its wide field of view and adaptability make it ideal to study nearby galaxies and even clusters of galaxies at large distances,” said co-author Laurent Drissen.

    Supernova explosions are among the most energetic and influential phenomena in the universe. Consequently, Milisavljevic adds: “It is vital that we understand the fundamental processes in supernovae which make life possible. SITELLE will play a new and exciting role in this understanding.”


    Flythrough of the Crab Nebula
    This 3D reconstruction of the Crab Nebula is made of 406,472 individual points where nebular emission has been detected in SITELLE spectra. The velocity of each element has been translated into a spatial position by assuming an unaccelerated outward motion. The glowing blue sphere at the centre is artificial and simulates the continuum emitted by the pulsar wind nebula. The Milky Way background (Credit: NASA / Goddard Space Flight Center Scientific Visualization Studio) simulates the perspective as observed when moving around the nebula. The soundtrack is a sonification of the data set: using the interferograms directly as a sound wave, multiple samples have been mixed and played at different rates. The sound volume is proportional to the distance to the nebula, and the playing speed simulates the Doppler effect. Credits: Thomas Martin, Danny Milisavljevic and Laurent Drissen.

    SITELLE is the result of a joint collaboration between Université Laval (CN), ABB Inc.-Québec (CN), Université de Montréal (CN) and the CFHT (US), under the scientific leadership of co-author Laurent Drissen.

    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 Royal Astronomical Society (UK), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,400 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

    The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

    In 2020 the RAS is 200 years old. The Society is celebrating its bicentennial anniversary with a series of events around the UK, including public lectures, exhibitions, an organ recital, a pop-up planetarium, and the culmination of the RAS 200: Sky & Earth project.

     
  • richardmitnick 3:40 pm on January 18, 2021 Permalink | Reply
    Tags: "Cosmic beasts and where to find them", , , , , , Royal Astronomical Society (UK),   

    From Royal Astronomical Society (UK): “Cosmic beasts and where to find them” 

    From Royal Astronomical Society (UK)

    15/01/2021

    Media contacts

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

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

    Science contact

    Dr Jacinta Delhaize
    Astronomy Department
    University of Cape Town
    jacinta@ast.uct.ac.za

    1
    Two giant radio galaxies found with the MeerKAT telescope. In the background is the sky as seen in optical light. Overlaid in red is the radio light from the enormous radio galaxies, as seen by MeerKAT. Left: MGTC J095959.63+024608.6. Right: MGTC J100016.84+015133.0. Credit:I. Heywood (Oxford/Rhodes/SARAO)
    Licence type Attribution (CC BY 4.0).

    Two giant radio galaxies have been discovered with South Africa’s powerful MeerKAT telescope. These galaxies are thought to be amongst the largest single objects in the Universe. The discovery has been published today in MNRAS.

    Whereas normal radio galaxies are fairly common, only a few hundred of these have radio jets exceeding 700 kilo-parsecs in size, or around 22 times the size of the Milky Way. These truly enormous systems are dubbed ‘giant radio galaxies’.

    Despite the scarcity of giant radio galaxies, the authors found two of these cosmic beasts in a remarkably small patch of sky.

    Dr Jacinta Delhaize, a Research Fellow at the University of Cape Town and lead author of the work, said: “We found these giant radio galaxies in a region of sky which is only about 4 times the area of the full Moon. Based on our current knowledge of the density of giant radio galaxies in the sky, the probability of finding two of them in this region is less than 0.0003 per cent.”

    “This means that giant radio galaxies are probably far more common than we thought!”

    Dr Matthew Prescott, a Research Fellow at the University of the Western Cape and co-author of the work, said, “These two galaxies are special because they are amongst the largest giants known, and in the top 10 per cent of all giant radio galaxies. They are more than 2 Mega-parsecs across, which is around 6.5 million light years or about 62 times the size of the Milky Way. Yet they are fainter than others of the same size.”

    “We suspect that many more galaxies like these should exist, because of the way we think galaxies grow and change over their lifetimes.”

    Why so few radio galaxies have such gigantic sizes remains something of a mystery. It is thought that the giants are the oldest radio galaxies, which have existed for long enough (several hundred million years) for their radio jets to grow outwards to these enormous sizes. If this is true, then many more giant radio galaxies should exist than are currently known.

    The giant radio galaxies were spotted in new radio maps of the sky created by the MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) survey. It is one of the large survey projects underway with South Africa’s impressive MeerKAT radio telescope, a precursor to the Square Kilometre Array (SKA), which is due to become fully operational in the mid-2020s.

    SKA- Square Kilometer Array

    SKA- South Africa.

    SKA SARAO Meerkat telescope, South African design.

    SKA Meerkat South Africa, SARAO, 90 km outside the small Northern Cape town of Carnarvon, SA.

    Dr Ian Heywood, a co-author at the University of Oxford, said “The MeerKAT telescope is the best of its kind in the world. We have managed to identify these giant radio galaxies for the first time because of MeerKAT’s unprecedented sensitivity to faint and diffuse radio light.”

    Dr Delhaize adds, “In the past, this population of galaxies has been hidden from our ‘sight’ by the technical limitations of radio telescopes. However, it is now being revealed thanks to the impressive capabilities of the new generation of telescopes.”

    Construction of the highly anticipated trans-continental SKA telescope is due to commence in South Africa and Australia in 2021, and continue until 2027. Science commissioning observations could begin as early as 2023, and it is hoped that the telescope will reveal larger populations of radio galaxies than ever before and revolutionise our understanding of galaxy evolution.

    See the full article here .

    Please help promote STEM in your local schools.


    Stem Education Coalition

    The Royal Astronomical Society (UK), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,400 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

    The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

    In 2020 the RAS is 200 years old. The Society is celebrating its bicentennial anniversary with a series of events around the UK, including public lectures, exhibitions, an organ recital, a pop-up planetarium, and the culmination of the RAS 200: Sky & Earth project.

     
  • richardmitnick 12:51 pm on November 13, 2020 Permalink | Reply
    Tags: "Family tree of the Milky Way deciphered", , , , , Royal Astronomical Society (UK)   

    From Royal Astronomical Society (UK): “Family tree of the Milky Way deciphered” 

    From Royal Astronomical Society (UK)

    11.13.20

    Media contacts

    Dr Guido Thimm
    Zentrum für Astronomie
    Heidelberg University
    Tel: +49 6221 54 1805
    thimm@ari.uni-heidelberg.de

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

    Science contacts

    Dr Diederik Kruijssen
    Zentrum für Astronomie
    Heidelberg University
    kruijssen@uni-heidelberg.de

    1
    Galaxy merger tree of the Milky Way inferred by applying the insights gained from the E-MOSAICS simulations to the Galactic globular cluster population. The main progenitor of the Milky Way is denoted by the trunk of the tree, coloured by its stellar mass. Black lines indicate the five identified satellites. Grey dotted lines illustrate other mergers that the Milky Way is predicted to have experienced, but could not be linked to a specific progenitor. From left to right, the six images along the top of the figure indicate the identified progenitor galaxies: Sagittarius, Sequoia, Kraken, the Milky Way’s Main progenitor, the progenitor of the Helmi streams, and Gaia-Enceladus-Sausage. Credit: D. Kruijssen / Heidelberg University (DE),Licence type Attribution (CC BY 4.0.

    Scientists have known for some time that galaxies can grow by the merging of smaller galaxies, but the ancestry of our own Milky Way galaxy has been a long-standing mystery. Now, an international team of astrophysicists has succeeded in reconstructing the first complete family tree of our home galaxy by analysing the properties of globular clusters orbiting the Milky Way with artificial intelligence. The work is published in MNRAS.

    Globular clusters are dense groups of up to a million stars that are almost as old as the Universe itself. The Milky Way hosts over 150 such clusters, many of which formed in the smaller galaxies that merged to form the galaxy that we live in today. Astronomers have suspected for decades that the old ages of globular clusters would mean that they could be used as “fossils” to reconstruct the early assembly histories of galaxies. However it is only with the latest models and observations that it has become possible to realise this promise.

    An international team of researchers led by Dr Diederik Kruijssen at the Center for Astronomy at the University of Heidelberg (ZAH) (DE) and Dr Joel Pfeffer at Liverpool John Moores University (UK) has now managed to infer the Milky Way’s merger history and reconstruct its family tree, using only its globular clusters.

    To achieve this, they developed a suite of advanced computer simulations of the formation of Milky Way-like galaxies. Their simulations, called E-MOSAICS, are unique because they include a complete model for the formation, evolution, and destruction of globular clusters.

    In the simulations, the researchers were able to relate the ages, chemical compositions, and orbital motions of globular clusters to the properties of the progenitor galaxies in which they formed, more than 10 billion years ago. By applying these insights to groups of globular clusters in the Milky Way, they could not only determine how many stars these progenitor galaxies contained, but also when they merged into the Milky Way.

    “The main challenge of connecting the properties of globular clusters to the merger history of their host galaxy has always been that galaxy assembly is an extremely messy process, during which the orbits of the globular clusters are completely reshuffled,” Kruijssen explains.

    “To make sense of the complex system that is left today, we therefore decided to use artificial intelligence. We trained an artificial neural network on the E-MOSAICS simulations to relate the globular cluster properties to the host galaxy merger history. We tested the algorithm tens of thousands of times on the simulations and were amazed at how accurately it was able to reconstruct the merger histories of the simulated galaxies, using only their globular cluster populations.”

    Inspired by this success, the researchers set out to decipher the merger history of the Milky Way. To achieve this, they used groups of globular clusters that are each thought to have formed in the same progenitor galaxy based on their orbital motion. By applying the neural network to these groups of globular clusters, the researchers could not only predict the stellar masses and merger times of the progenitor galaxies to high precision, but it also revealed a previously unknown collision between the Milky Way and an enigmatic galaxy, which the researchers named “Kraken”.

    “The collision with Kraken must have been the most significant merger the Milky Way ever experienced,” Kruijssen adds.

    “Before, it was thought that a collision with the Gaia-Enceladus-Sausage galaxy, which took place some 9 billion years ago, was the biggest collision event.

    2
    A visualization of the moment of impact between the MW’s progenitor and the Gaia Sausage (or Gaia-Enceladus) (credit: Instituto de Astrofísica de Canarias (ES)).

    However, the merger with Kraken took place 11 billion years ago, when the Milky Way was four times less massive. As a result, the collision with Kraken must have truly transformed what the Milky Way looked like at the time.”

    Taken together, these findings allowed the team of researchers to reconstruct the first complete merger tree of our Galaxy. Over the course of its history, the Milky Way canibalised about five galaxies with more than 100 million stars, and about fifteen with at least 10 million stars. The most massive progenitor galaxies collided with the Milky Way between 6 and 11 billion years ago.

    The researchers expect their predictions to stimulate future studies to search for the remains of these progenitor galaxies. “The debris of more than five progenitor galaxies has now been identified. With current and upcoming telescopes, it should be possible to find them all,” Kruijssen concludes.

    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 Royal Astronomical Society (RAS) (UK), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 3:50 pm on November 6, 2020 Permalink | Reply
    Tags: "Seeing dark matter in a new light", , , , , Royal Astronomical Society (UK), Weak gravitational lensing is already one of the most successful ways to map the dark matter content of the Universe.   

    From Royal Astronomical Society (UK): “Seeing dark matter in a new light” 

    From Royal Astronomical Society (UK)

    1
    Artist’s impression of a galaxy surrounded by gravitational distortions due to dark matter. Galaxies live inside larger concentrations of invisible dark matter (coloured purple in this image), however the dark matter’s effects can be seen by looking at the deformations of background galaxies. Credit: Swinburne Astronomy Productions – James Josephides.

    A small team of astronomers have found a new way to ‘see’ the elusive dark matter haloes that surround galaxies, with a new technique 10 times more precise than the previous-best method. The work is published in MNRAS.

    Scientists currently estimate that up to 85% of the mass in the universe is effectively invisible. This “dark matter” cannot be observed directly, because it does not interact with light in the same way as the ordinary matter that makes up stars, planets, and life on Earth.

    So how do we measure what cannot be seen? The key is to measure the effect of gravity that the dark matter produces.

    Pol Gurri, the Ph.D. student at Swinburne University of Technology who led the new research, explains: “It’s like looking at a flag to try to know how much wind there is. You cannot see the wind, but the flag’s motion tells you how strongly the wind is blowing.”

    The new research focuses on an effect called weak gravitational lensing, which is a feature of Einstein’s general theory of relativity.

    Weak gravitational lensing NASA/ESA Hubble.

    “The dark matter will very slightly distort the image of anything behind it,” says Associate Professor Edward Taylor, who was also involved in the research. “The effect is a bit like reading a newspaper through the base of a wine glass.”

    2
    Processed image of a spiral galaxy, as might be observed after lensing effects have distorted the galaxy’s true shape. By measuring the orbital motion of gas within a distant galaxy (seen here in pink), gravitational distortions can be measured much more precisely than was previously possible. Credit: Original image by ESA / Hubble & NASA / Flickr user Det58, image modification by Pol Gurri.

    Weak gravitational lensing is already one of the most successful ways to map the dark matter content of the Universe. Now, the Swinburne team has used the ANU 2.3m Telescope in Australia to map how gravitationally lensed galaxies are rotating. “Because we know how stars and gas are supposed to move inside galaxies, we know roughly what that galaxy should look like,” says Gurri. “By measuring how distorted the real galaxy images are, then we can figure out how much dark matter it would take to explain what we see.”

    The new research shows how this velocity information enables a much more precise measurement of the lensing effect than is possible using shape alone. “With our new way of seeing the dark matter,” Gurri says, “we hope to get a clearer picture of where the dark matter is, and what role it plays in how galaxies form.”

    ANU Siding Spring 2.3 meter telescope, Siding Spring Observatory, Coonabarabran, Warrumbungle National Park, NSW. Siding Spring Mountain [Mount Woorat] with Anglo-Australian Telescope dome visible near centre of image at an altitude of 1,165 m (3,822 ft).

    Future space missions such as NASA’s Nancy Grace Roman Space Telescope and the European Space Agency’s Euclid Space Telescope are designed, in part, to make these kinds of measurements based on the shapes of hundreds of millions of galaxies.

    NASA Nancy Grace Roman Space Telescope.

    ESA/Euclid spacecraft depiction

    “We have shown that we can make a real contribution to these global efforts with a relatively small telescope built in the 1980s, just by thinking about the problem in a different way,” adds Taylor.

    See the full article here .

    Please help promote STEM in your local schools.


    Stem Education Coalition

    The Royal Astronomical Society (UK), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,400 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

    The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

    In 2020 the RAS is 200 years old. The Society is celebrating its bicentennial anniversary with a series of events around the UK, including public lectures, exhibitions, an organ recital, a pop-up planetarium, and the culmination of the RAS 200: Sky & Earth project.

     
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