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  • richardmitnick 10:14 pm on July 21, 2021 Permalink | Reply
    Tags: "Planetary shields will buckle under stellar winds from their dying stars", All stars eventually run out of available hydrogen that fuels the nuclear fusion in their cores., Any life identified on planets orbiting white dwarf stars almost certainly evolved after the star’s death., , , , , In our solar system the habitable zone of the red giant sun would move from about 150 million km from the Sun-where Earth is currently positioned-up to 6 billion km or beyond Neptune., It is nearly impossible for life to survive cataclysmic stellar evolution unless the planet has an intensely strong magnetic field – or magnetosphere - that can shield it from the worst effects., Once the white dwarf star reaches this stage the danger to surviving planets has passed., Red Giant Stars, the loss of mass in the red giant star means it has a weaker gravitational pull so the remaining planets move further away., The process of stellar evolution also results in a shift in a star’s habitable zone which is the distance that would allow a planet to be the right temperature to support liquid water., The scientists found that the habitable zone moves outward more quickly than the planet posing additional challenges to any existing life hoping to survive the process., The Sun will then stretch to a diameter of tens of millions of kilometres as a red giant swallowing the inner planets possibly including the Earth., Two known gas giants are close enough to their white dwarf star’s habitable zone to suggest that life on such a planet could exist., ,   

    From University of Warwick (UK) : “Planetary shields will buckle under stellar winds from their dying stars” 

    From University of Warwick (UK)

    21 July 2021

    Peter Thorley
    Media Relations Manager (Warwick Medical School and Department of Physics) | Press & Media Relations | University of Warwick
    Email: peter.thorley@warwick.ac.uk
    Mob: +44 (0) 7824 540863

    1
    An illustration of material being ejected from the Sun (left) interacting with the magnetosphere of the Earth (right). When the Sun evolves to become a red giant star, the Earth may be swallowed by our star’s atmosphere, and with a much more unstable solar wind, even the resilient and protective magnetospheres of the giant outer planets may be stripped away.NASA Marshall Space Flight Center (US) / National Aeronautics Space Agency (US).

    Any life identified on planets orbiting white dwarf stars almost certainly evolved after the star’s death, says a new study led by the University of Warwick that reveals the consequences of the intense and furious stellar winds that will batter a planet as its star is dying.

    The research is published in MNRAS, and lead author Dr Dimitri Veras of the University of Warwick will present it today (21 July) at the online National Astronomy Meeting (NAM 2021).

    The research provides new insight for astronomers searching for signs of life around these dead stars by examining the impact that their winds will have on orbiting planets during the star’s transition to the white dwarf stage. The study concludes that it is nearly impossible for life to survive cataclysmic stellar evolution unless the planet has an intensely strong magnetic field – or magnetosphere – that can shield it from the worst effects.

    In the case of Earth, solar wind particles can erode the protective layers of the atmosphere that shield humans from harmful ultraviolet radiation. The terrestrial magnetosphere acts like a shield to divert those particles away through its magnetic field. Not all planets have a magnetosphere, but Earth’s is generated by its iron core, which rotates like a dynamo to create its magnetic field.

    All stars eventually run out of available hydrogen that fuels the nuclear fusion in their cores. In the Sun the core will then contract and heat up, driving an enormous expansion of the outer atmosphere of the star into a ‘red giant’. The Sun will then stretch to a diameter of tens of millions of kilometres, swallowing the inner planets, possibly including the Earth. At the same time the loss of mass in the star means it has a weaker gravitational pull so the remaining planets move further away.

    The Sun will then stretch to a diameter of tens of millions of kilometres, swallowing the inner planets, possibly including the Earth. At the same time the loss of mass in the star means it has a weaker gravitational pull, so the remaining planets move further away.

    During the red giant phase, the solar wind will be far stronger than today, and it will fluctuate dramatically. Veras and Vidotto modelled the winds from 11 different types of stars, with masses ranging from one to seven times the mass of our Sun.

    Their model demonstrated how the density and speed of the stellar wind, combined with an expanding planetary orbit, conspires to alternatively shrink and expand the magnetosphere of a planet over time. For any planet to maintain its magnetosphere throughout all stages of stellar evolution, its magnetic field needs to be at least one hundred times stronger than Jupiter’s current magnetic field.

    The process of stellar evolution also results in a shift in a star’s habitable zone which is the distance that would allow a planet to be the right temperature to support liquid water. In our solar system the habitable zone would move from about 150 million km from the Sun-where Earth is currently positioned-up to 6 billion km or beyond Neptune. Although an orbiting planet would also change position during the giant branch phases, the scientists found that the habitable zone moves outward more quickly than the planet posing additional challenges to any existing life hoping to survive the process.

    Eventually the red giant sheds its entire outer atmosphere, leaving behind the dense hot white dwarf remnant. These do not emit stellar winds, so once the star reaches this stage the danger to surviving planets has passed.

    Dr Dimitri Veras of the University of Warwick Department of Physics said: “This study demonstrates the difficulty of a planet maintaining its protective magnetosphere throughout the entirety of the giant branch phases of stellar evolution.”

    “One conclusion is that life on a planet in the habitable zone around a white dwarf would almost certainly develop during the white dwarf phase unless that life was able to withstand multiple extreme and sudden changes in its environment.”

    “We know that the solar wind in the past eroded the Martian atmosphere, which, unlike Earth, does not have a large-scale magnetosphere. What we were not expecting to find is that the solar wind in the future could be as damaging even to those planets that are protected by a magnetic field”, says Dr Aline Vidotto of Trinity College Dublin, the University of Dublin(IE), the co-author of the study.

    Future missions like the James Webb Space Telescope due to be launched later this year should reveal more about planets that orbit white dwarf stars, including whether planets within their habitable zones show biomarkers that indicate the presence of life, so the study provides valuable context to any potential discoveries.

    So far no terrestrial planet that could support life around a white dwarf has been found, but two known gas giants are close enough to their star’s habitable zone to suggest that such a planet could exist. These planets likely moved in closer to the white dwarf as a result of interactions with other planets further out.

    Dr Veras adds: “These examples show that giant planets can approach very close to the habitable zone. The habitable zone for a white dwarf is very close to the star because they emit much less light than a Sun-like star. However, white dwarfs are also very steady stars as they have no winds. A planet that’s parked in the white dwarf habitable zone could remain there for billions of years, allowing time for life to develop provided that the conditions are suitable.”

    See the full article here.

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    The establishment of the The University of Warwick (UK) was given approval by the government in 1961 and received its Royal Charter of Incorporation in 1965.

    The idea for a university in Coventry was mooted shortly after the conclusion of the Second World War but it was a bold and imaginative partnership of the City and the County which brought the University into being on a 400-acre site jointly granted by the two authorities. Since then, the University has incorporated the former Coventry College of Education in 1978 and has extended its land holdings by the purchase of adjoining farm land.

    The University initially admitted a small intake of graduate students in 1964 and took its first 450 undergraduates in October 1965. In October 2013, the student population was over 23,000 of which 9,775 are postgraduates. Around a third of the student body comes from overseas and over 120 countries are represented on the campus.

    The University of Warwick is a public research university on the outskirts of Coventry between the West Midlands and Warwickshire, England. The University was founded in 1965 as part of a government initiative to expand higher education. The Warwick Business School was established in 1967, the Warwick Law School in 1968, Warwick Manufacturing Group (WMG) in 1980, and Warwick Medical School in 2000. Warwick incorporated Coventry College of Education in 1979 and Horticulture Research International in 2004.

    Warwick is primarily based on a 290 hectares (720 acres) campus on the outskirts of Coventry, with a satellite campus in Wellesbourne and a central London base at the Shard. It is organised into three faculties — Arts, Science Engineering and Medicine, and Social Sciences — within which there are 32 departments. As of 2019, Warwick has around 26,531 full-time students and 2,492 academic and research staff. It had a consolidated income of £679.9 million in 2019/20, of which £131.7 million was from research grants and contracts. Warwick Arts Centre is a multi-venue arts complex in the university’s main campus and is the largest venue of its kind in the UK, which is not in London.

    Warwick has an average intake of 4,950 undergraduates out of 38,071 applicants (7.7 applicants per place).

    Warwick is a member of Association of Commonwealth Universities (UK), the Association of MBAs, EQUIS, the European University Association (EU), the Midlands Innovation group, the Russell Group (UK), Sutton 13. It is the only European member of the Center for Urban Science and Progress, a collaboration with New York University (US). The university has extensive commercial activities, including the University of Warwick Science Park and Warwick Manufacturing Group.

    Warwick’s alumni and staff include winners of the Nobel Prize, Turing Award, Fields Medal, Richard W. Hamming Medal, Emmy Award, Grammy, and the Padma Vibhushan, and are fellows to the British Academy, the Royal Society of Literature, the Royal Academy of Engineering, and the Royal Society. Alumni also include heads of state, government officials, leaders in intergovernmental organisations, and the current chief economist at the Bank of England. Researchers at Warwick have also made significant contributions such as the development of penicillin, music therapy, Washington Consensus, Second-wave feminism, computing standards, including ISO and ECMA, complexity theory, contract theory, and the International Political Economy as a field of study.

    Twentieth century

    The idea for a university in Warwickshire was first mooted shortly after World War II, although it was not founded for a further two decades. A partnership of the city and county councils ultimately provided the impetus for the university to be established on a 400-acre (1.6 km^2) site jointly granted by the two authorities. There was some discussion between local sponsors from both the city and county over whether it should be named after Coventry or Warwickshire. The name “University of Warwick” was adopted, even though Warwick, the county town, lies some 8 miles (13 km) to its southwest and Coventry’s city centre is only 3.5 miles (5.6 km) northeast of the campus. The establishment of the University of Warwick was given approval by the government in 1961 and it received its Royal Charter of Incorporation in 1965. Since then, the university has incorporated the former Coventry College of Education in 1979 and has extended its land holdings by the continuing purchase of adjoining farm land. The university also benefited from a substantial donation from the family of John ‘Jack’ Martin, a Coventry businessman who had made a fortune from investment in Smirnoff vodka, and which enabled the construction of the Warwick Arts Centre.

    The university initially admitted a small intake of graduate students in 1964 and took its first 450 undergraduates in October 1965. Since its establishment Warwick has expanded its grounds to 721 acres (2.9 km^2), with many modern buildings and academic facilities, lakes, and woodlands. In the 1960s and 1970s, Warwick had a reputation as a politically radical institution.

    Under Vice-Chancellor Lord Butterworth, Warwick was the first UK university to adopt a business approach to higher education, develop close links with the business community and exploit the commercial value of its research. These tendencies were discussed by British historian and then-Warwick lecturer, E. P. Thompson, in his 1970 edited book Warwick University Ltd.

    The Leicester Warwick Medical School, a new medical school based jointly at Warwick and University of Leicester (UK), opened in September 2000.

    On the recommendation of Tony Blair, Bill Clinton chose Warwick as the venue for his last major foreign policy address as US President in December 2000. Sandy Berger, Clinton’s National Security Advisor, explaining the decision in a press briefing on 7 December 2000, said that: “Warwick is one of Britain’s newest and finest research universities, singled out by Prime Minister Blair as a model both of academic excellence and independence from the government.”

    Twenty-first century
    The university was seen as a favoured institution of the Labour government during the New Labour years (1997 to 2010). It was academic partner for a number of flagship Government schemes including the National Academy for Gifted and Talented Youth and the NHS University (now defunct). Tony Blair described Warwick as “a beacon among British universities for its dynamism, quality and entrepreneurial zeal”. In a 2012 study by Virgin Media Business, Warwick was described as the most “digitally-savvy” UK university.

    In February 2001, IBM donated a new S/390 computer and software worth £2 million to Warwick, to form part of a “Grid” enabling users to remotely share computing power. In April 2004 Warwick merged with the Wellesbourne and Kirton sites of Horticulture Research International. In July 2004 Warwick was the location for an important agreement between the Labour Party and the trade unions on Labour policy and trade union law, which has subsequently become known as the “Warwick Agreement”.

    In June 2006 the new University Hospital Coventry opened, including a 102,000 sq ft (9,500 m^2) university clinical sciences building. Warwick Medical School was granted independent degree-awarding status in 2007, and the School’s partnership with the University of Leicester was dissolved in the same year. In February 2010, Lord Bhattacharyya, director and founder of the WMG unit at Warwick, made a £1 million donation to the university to support science grants and awards.

    In February 2012 Warwick and Melbourne-based Monash University (AU) announced the formation of a strategic partnership, including the creation of 10 joint senior academic posts, new dual master’s and joint doctoral degrees, and co-ordination of research programmes. In March 2012 Warwick and Queen Mary, University of London announced the creation of a strategic partnership, including research collaboration, some joint teaching of English, history and computer science undergraduates, and the creation of eight joint post-doctoral research fellowships.

    In April 2012 it was announced that Warwick would be the only European university participating in the Center for Urban Science and Progress, an applied science research institute to be based in New York consisting of an international consortium of universities and technology companies led by New York University and NYU Tandon School of Engineering (US). In August 2012, Warwick and five other Midlands-based universities — Aston University (UK), the University of Birmingham (UK), the University of Leicester (UK), Loughborough University (UK) and the University of Nottingham — formed the M5 Group, a regional bloc intended to maximise the member institutions’ research income and enable closer collaboration.

    In September 2013 it was announced that a new National Automotive Innovation Centre would be built by WMG at Warwick’s main campus at a cost of £100 million, with £50 million to be contributed by Jaguar Land Rover and £30 million by Tata Motors.

    In July 2014, the government announced that Warwick would be the host for the £1 billion Advanced Propulsion Centre, a joint venture between the Automotive Council and industry. The ten-year programme intends to position the university and the UK as leaders in the field of research into the next generation of automotive technology.

    In September 2015, Warwick celebrated its 50th anniversary (1965–2015) and was designated “University of the Year” by The Times and The Sunday Times.

    Research

    In 2013/14 Warwick had a total research income of £90.1 million, of which £33.9 million was from Research Councils; £25.9 million was from central government, local authorities and public corporations; £12.7 million was from the European Union; £7.9 million was from UK industry and commerce; £5.2 million was from UK charitable bodies; £4.0 million was from overseas sources; and £0.5 million was from other sources.

    In the 2014 UK Research Excellence Framework (REF), Warwick was again ranked 7th overall (as 2008) amongst multi-faculty institutions and was the top-ranked university in the Midlands. Some 87% of the University’s academic staff were rated as being in “world-leading” or “internationally excellent” departments with top research ratings of 4* or 3*.

    Warwick is particularly strong in the areas of decision sciences research (economics, finance, management, mathematics and statistics). For instance, researchers of the Warwick Business School have won the highest prize of the prestigious European Case Clearing House (ECCH: the equivalent of the Oscars in terms of management research).

    Warwick has established a number of stand-alone units to manage and extract commercial value from its research activities. The four most prominent examples of these units are University of Warwick Science Park; Warwick HRI; Warwick Ventures (the technology transfer arm of the University); and WMG.

     
  • richardmitnick 8:38 am on July 16, 2019 Permalink | Reply
    Tags: , , , , , , Red Giant Stars   

    From NASA/ESA Hubble Telescope: “New Hubble Constant Measurement Adds to Mystery of Universe’s Expansion Rate” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope


    From NASA/ESA Hubble Telescope

    July 16, 2019

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    Louise Lerner
    University of Chicago, Chicago, Illinois
    773-702-8366
    louise@uchicago.edu

    1
    About This Image

    These galaxies are selected from a Hubble Space Telescope program to measure the expansion rate of the universe, called the Hubble constant. The value is calculated by comparing the galaxies’ distances to the apparent rate of recession away from Earth (due to the relativistic effects of expanding space).

    By comparing the apparent brightnesses of the galaxies’ red giant stars with nearby red giants, whose distances were measured with other methods, astronomers are able to determine how far away each of the host galaxies are. This is possible because red giants are reliable milepost markers because they all reach the same peak brightness in their late evolution. And, this can be used as a “standard candle” to calculate distance. Hubble’s exquisite sharpness and sensitivity allowed for red giants to be found in the stellar halos of the host galaxies.

    The red giants were searched for in the halos of the galaxies. The center row shows Hubble’s full field of view. The bottom row zooms even tighter into the Hubble fields. The red giants are identified by yellow circles. Credits: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey

    ________________________________________________________
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    About This Image: Credits: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey

    ________________________________________________________

    3

    Red Giant Stars Used as Milepost Markers

    Astronomers have made a new measurement of how fast the universe is expanding, using an entirely different kind of star than previous endeavors. The revised measurement, which comes from NASA’s Hubble Space Telescope, falls in the center of a hotly debated question in astrophysics that may lead to a new interpretation of the universe’s fundamental properties.

    Scientists have known for almost a century that the universe is expanding, meaning the distance between galaxies across the universe is becoming ever more vast every second. But exactly how fast space is stretching, a value known as the Hubble constant, has remained stubbornly elusive.

    Now, University of Chicago professor Wendy Freedman and colleagues have a new measurement for the rate of expansion in the modern universe, suggesting the space between galaxies is stretching faster than scientists would expect. Freedman’s is one of several recent studies that point to a nagging discrepancy between modern expansion measurements and predictions based on the universe as it was more than 13 billion years ago, as measured by the European Space Agency’s Planck satellite.

    ESA/Planck 2009 to 2013

    As more research points to a discrepancy between predictions and observations, scientists are considering whether they may need to come up with a new model for the underlying physics of the universe in order to explain it.

    “The Hubble constant is the cosmological parameter that sets the absolute scale, size and age of the universe; it is one of the most direct ways we have of quantifying how the universe evolves,” said Freedman. “The discrepancy that we saw before has not gone away, but this new evidence suggests that the jury is still out on whether there is an immediate and compelling reason to believe that there is something fundamentally flawed in our current model of the universe.”

    In a new paper accepted for publication in The Astrophysical Journal, Freedman and her team announced a new measurement of the Hubble constant using a kind of star known as a red giant. Their new observations, made using Hubble, indicate that the expansion rate for the nearby universe is just under 70 kilometers per second per megaparsec (km/sec/Mpc). One parsec is equivalent to 3.26 light-years distance.

    This measurement is slightly smaller than the value of 74 km/sec/Mpc recently reported by the Hubble SH0ES (Supernovae H0 for the Equation of State) team using Cepheid variables, which are stars that pulse at regular intervals that correspond to their peak brightness. This team, led by Adam Riess of the Johns Hopkins University and Space Telescope Science Institute, Baltimore, Maryland, recently reported refining their observations to the highest precision to date for their Cepheid distance measurement technique.

    How to Measure Expansion

    A central challenge in measuring the universe’s expansion rate is that it is very difficult to accurately calculate distances to distant objects.

    In 2001, Freedman led a team that used distant stars to make a landmark measurement of the Hubble constant. The Hubble Space Telescope Key Project team measured the value using Cepheid variables as distance markers. Their program concluded that the value of the Hubble constant for our universe was 72 km/sec/Mpc.

    But more recently, scientists took a very different approach: building a model based on the rippling structure of light left over from the big bang, which is called the Cosmic Microwave Background [CMB].

    CMB per ESA/Planck

    The Planck measurements allow scientists to predict how the early universe would likely have evolved into the expansion rate astronomers can measure today. Scientists calculated a value of 67.4 km/sec/Mpc, in significant disagreement with the rate of 74.0 km/sec/Mpc measured with Cepheid stars.

    Astronomers have looked for anything that might be causing the mismatch. “Naturally, questions arise as to whether the discrepancy is coming from some aspect that astronomers don’t yet understand about the stars we’re measuring, or whether our cosmological model of the universe is still incomplete,” Freedman said. “Or maybe both need to be improved upon.”

    Freedman’s team sought to check their results by establishing a new and entirely independent path to the Hubble constant using an entirely different kind of star.

    Certain stars end their lives as a very luminous kind of star called a red giant, a stage of evolution that our own Sun will experience billions of years from now. At a certain point, the star undergoes a catastrophic event called a helium flash, in which the temperature rises to about 100 million degrees and the structure of the star is rearranged, which ultimately dramatically decreases its luminosity. Astronomers can measure the apparent brightness of the red giant stars at this stage in different galaxies, and they can use this as a way to tell their distance.

    The Hubble constant is calculated by comparing distance values to the apparent recessional velocity of the target galaxies — that is, how fast galaxies seem to be moving away. The team’s calculations give a Hubble constant of 69.8 km/sec/Mpc — straddling the values derived by the Planck and Riess teams.

    “Our initial thought was that if there’s a problem to be resolved between the Cepheids and the Cosmic Microwave Background, then the red giant method can be the tie-breaker,” said Freedman.

    But the results do not appear to strongly favor one answer over the other say the researchers, although they align more closely with the Planck results.

    NASA’s upcoming mission, the Wide Field Infrared Survey Telescope (WFIRST), scheduled to launch in the mid-2020s, will enable astronomers to better explore the value of the Hubble constant across cosmic time.

    NASA/WFIRST

    WFIRST, with its Hubble-like resolution and 100 times greater view of the sky, will provide a wealth of new Type Ia supernovae, Cepheid variables, and red giant stars to fundamentally improve distance measurements to galaxies near and far.

    More links at the full article.

    See the full article here .


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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

    AURA Icon

     
  • richardmitnick 2:28 pm on January 12, 2019 Permalink | Reply
    Tags: Astronomers find signatures of a ‘messy’ star that made its companion go supernova, , , , , , It takes many astronomers and a wide variety of types of telescopes working together to understand transient cosmic phenomena, Red Giant Stars, SN 2015cp, , ,   

    From University of Washington: “Astronomers find signatures of a ‘messy’ star that made its companion go supernova” 

    U Washington

    From University of Washington

    January 10, 2019
    James Urton

    1
    An X-ray/infrared composite image of G299, a Type Ia supernova remnant in the Milky Way Galaxy approximately 16,000 light years away.NASA/Chandra X-ray Observatory/University of Texas/2MASS/University of Massachusetts/Caltech/NSF

    NASA/Chandra X-ray Telescope


    Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, Altitude 2,606 m (8,550 ft) and at the Cerro Tololo Inter-American Observatory at an altitude of 2200 meters near La Serena, Chile.

    Many stars explode as luminous supernovae when, swollen with age, they run out of fuel for nuclear fusion. But some stars can go supernova simply because they have a close and pesky companion star that, one day, perturbs its partner so much that it explodes.

    These latter events can happen in binary star systems, where two stars attempt to share dominion. While the exploding star gives off lots of evidence about its identity, astronomers must engage in detective work to learn about the errant companion that triggered the explosion.

    On Jan. 10 at the 2019 American Astronomical Society meeting in Seattle, an international team of astronomers announced that they have identified the type of companion star that made its partner in a binary system, a carbon-oxygen white dwarf star, explode. Through repeated observations of SN 2015cp, a supernova 545 million light years away, the team detected hydrogen-rich debris that the companion star had shed prior to the explosion.

    “The presence of debris means that the companion was either a red giant star or similar star that, prior to making its companion go supernova, had shed large amounts of material,” said University of Washington astronomer Melissa Graham, who presented the discovery and is lead author on the accompanying paper accepted for publication in The Astrophysical Journal.

    The supernova material smacked into this stellar litter at 10 percent the speed of light, causing it to glow with ultraviolet light that was detected by the Hubble Space Telescope and other observatories nearly two years after the initial explosion. By looking for evidence of debris impacts months or years after a supernova in a binary star system, the team believes that astronomers could determine whether the companion had been a messy red giant or a relatively neat and tidy star.

    The team made this discovery as part of a wider study of a particular type of supernova known as a Type Ia supernova. These occur when a carbon-oxygen white dwarf star explodes suddenly due to activity of a binary companion. Carbon-oxygen white dwarfs are small, dense and — for stars — quite stable. They form from the collapsed cores of larger stars and, if left undisturbed, can persist for billions of years.

    Type Ia supernovae have been used for cosmological studies because their consistent luminosity makes them ideal “cosmic lighthouses,” according to Graham. They’ve been used to estimate the expansion rate of the universe and served as indirect evidence for the existence of dark energy.

    2
    An image of SN 1994D (lower left), a Type Ia supernova detected in 1994 at the edge of galaxy NGC 4526 (center).NASA/ESA/The Hubble Key Project Team/The High-Z Supernova Search Team.

    NASA/ESA Hubble Telescope

    Yet scientists are not certain what kinds of companion stars could trigger a Type Ia event. Plenty of evidence indicates that, for most Type Ia supernovae, the companion was likely another carbon-oxygen white dwarf, which would leave no hydrogen-rich debris in the aftermath. Yet theoretical models have shown that stars like red giants could also trigger a Type Ia supernova, which could leave hydrogen-rich debris that would be hit by the explosion. Out of the thousands of Type Ia supernovae studied to date, only a small fraction were later observed impacting hydrogen-rich material shed by a companion star. Prior observations of at least two Type Ia supernovae detected glowing debris months after the explosion. But scientists weren’t sure if those events were isolated occurrences, or signs that Type Ia supernovae could have many different kinds of companion stars.

    “All of the science to date that has been done using Type Ia supernovae, including research on dark energy and the expansion of the universe, rests on the assumption that we know reasonably well what these ‘cosmic lighthouses’ are and how they work,” said Graham. “It is very important to understand how these events are triggered, and whether only a subset of Type Ia events should be used for certain cosmology studies.”

    The team used Hubble Space Telescope observations to look for ultraviolet emissions from 70 Type Ia supernovae approximately one to three years following the initial explosion.

    “By looking years after the initial event, we were searching for signs of shocked material that contained hydrogen, which would indicate that the companion was something other than another carbon-oxygen white dwarf,” said Graham.

    In the case of SN 2015cp, a supernova first detected in 2015, the scientists found what they were searching for. In 2017, 686 days after the supernova exploded, Hubble picked up an ultraviolet glow of debris. This debris was far from the supernova source — at least 100 billion kilometers, or 62 billion miles, away. For reference, Pluto’s orbit takes it a maximum of 7.4 billion kilometers from our sun.

    3
    In 2017, 686 days after the initial explosion, the Hubble Space Telescope recorded an ultraviolet emission (blue circle) from SN 2015cp, which was caused by supernova material impacting hydrogen-rich material previously shed by a companion star. Yellow circles indicate cosmic ray strikes, which are unrelated to the supernova. NASA/Hubble Space Telescope/Graham et al. 2019.

    By comparing SN 2015cp to the other Type Ia supernovae in their survey, the researchers estimate that no more than 6 percent of Type Ia supernovae have such a litterbug companion. Repeated, detailed observations of other Type Ia events would help cement these estimates, Graham said.

    The Hubble Space Telescope was essential for detecting the ultraviolet signature of the companion star’s debris for SN 2015cp. In the fall of 2017, the researchers arranged for additional observations of SN 2015cp by the W.M. Keck Observatory in Hawaii, the Karl G. Jansky Very Large Array in New Mexico, the European Southern Observatory’s Very Large Telescope and NASA’s Neil Gehrels Swift Observatory, among others. These data proved crucial in confirming the presence of hydrogen and are presented in a companion paper lead by Chelsea Harris, a research associate at Michigan State University.

    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level,

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo, with an elevation of 2,635 metres (8,645 ft) above sea level,

    NASA Neil Gehrels Swift Observatory

    “The discovery and follow-up of SN 2015cp’s emission really demonstrates how it takes many astronomers, and a wide variety of types of telescopes, working together to understand transient cosmic phenomena,” said Graham. “It is also a perfect example of the role of serendipity in astronomical studies: If Hubble had looked at SN 2015cp just a month or two later, we wouldn’t have seen anything.”

    Graham is also a senior fellow with the UW’s DIRAC Institute and a science analyst with the Large Synoptic Survey Telescope, or LSST.

    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes, altitude 2,663 m (8,737 ft),

    “In the future, as a part of its regularly scheduled observations, the LSST will automatically detect optical emissions similar to SN 2015cp — from hydrogen impacted by material from Type Ia supernovae,” said Graham said. “It’s going to make my job so much easier!”

    Co-authors are Harris; Peter Nugent at the University of California, Berkeley and the Lawrence Berkeley National Laboratory; Kate Maguire at Queen’s University Belfast; Mark Sullivan and Mathew Smith at the University of Southampton; Stefano Valenti at the University of California, Davis; Ariel Goobar at Stockholm University; Ori Fox at the Space Telescope Science Institute; Ken Shen, Tom Brink and Alex Filippenko at the University of California, Berkeley; Patrick Kelly at the University of Minnesota; and Curtis McCully at the University of California, Santa Barbara and the Las Cumbres Observatory. The research was funded by the National Science Foundation, NASA, the European Research Council and the U.K.’s Science and Technology Facilities Council.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    u-washington-campus
    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
    So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 2:52 pm on August 30, 2018 Permalink | Reply
    Tags: , , , , Nothing left but hot rocky ashes, Red Giant Stars, Which Worlds Will Survive When The Sun Dies?   

    From Ethan Siegel: “Which Worlds Will Survive When The Sun Dies?” 

    From Ethan Siegel
    Aug 30, 2018

    For the Pluto fans, another sad state of affairs: your favorite world won’t make it.

    1
    When our Sun runs out of fuel, it will become a red giant, followed by a planetary nebula with a white dwarf at the center. The Cat’s Eye nebula is a visually spectacular example of this potential fate, with the intricate, layered, asymmetrical shape of this particular one suggesting a binary companion. (NASA, ESA, HEIC, AND THE HUBBLE HERITAGE TEAM (STSCI/AURA); ACKNOWLEDGMENT: R. CORRADI (ISAAC NEWTON GROUP OF TELESCOPES, SPAIN) AND Z. TSVETANOV (NASA))

    NASA/ESA Hubble Telescope

    Isaac Newton Group telescopes, at Roque de los Muchachos Observatory on La Palma in the Canary Islands, Spain, at an altitude of 2400m

    Nothing on Earth lasts forever, and that’s a truth that even extends to all the objects we can see in our sky. The Sun, giver of light and heat to every world in our Solar System, shines on borrowed time. Currently fusing hydrogen into helium in its core, the Sun gets its energy by converting small amounts of mass into pure energy — via Einstein’s E = mc² — with every nuclear reaction that takes place.

    This cannot last forever, as the core’s fuel is finite. The Sun has already lost the equivalent of the mass of Saturn through this process, and in 5-to-7 billion years, will run out of its core fuel entirely. After swelling into a red giant, it will eventually blow off its outer layers, creating a planetary nebula, with its core contracting down to a white dwarf. It will be a beautiful, spectacular sight to an outsider. But inside our Solar System, it will lead to catastrophe everywhere.

    White dwarf star by Miriam Nielsen

    3
    The Sun, today, is very small compared to giants, but will grow to the size of Arcturus in its red giant phase, some 250 times its current size. A monstrous supergiant like Antares will be forever beyond our Sun’s reach. (ENGLISH WIKIPEDIA AUTHOR SAKURAMBO)

    The first thing to know about a red giant is that it’s huge. We think of our Sun as large: some 1.4 million kilometers across and weighing in at 300,000 times the mass of our Earth, but that size is nothing compared to a red giant. With the same mass, our Sun will grow to over 100 times its present size, engulfing both Mercury and Venus. Earth will likely be pushed out as the Sun expands and loses mass, and although it may be engulfed, scientists are split about the possibility of whether it will survive or not [even if Earth survives, it will be uninhabitable, fried].

    4
    The Earth, if calculations are correct, should not be engulfed by the Sun when it swells into a red giant. It should, however, become very, very hot, and will experience catastrophic changes [I think I just said that]. (WIKIMEDIA COMMONS USER FSGREGS)

    If it does, though, both Earth and Mars will become charred, barren worlds. The oceans and atmospheres of these planets will boil and be stripped away, and we will become airless, roasting worlds just like Mercury is today. These effects will extend far beyond the inner, rocky worlds of the Solar System.

    You see, red giants aren’t just large, they’re still many thousands of degrees, while shining thousands of times as luminous as our Sun does today. Much of the ejected material — between a third and half the mass of the Sun — will make its way at extreme temperatures into the outer portions of our Solar System. The asteroids will melt, losing all of their volatile components, leaving only their rocky nuclei behind.

    But the gas giant worlds are massive enough to continue to hold onto their gas envelopes, perhaps destined to even grow as the Sun enters this phase. The planets we find around red giant stars today, for example, are all gas giants and are much larger than even Jupiter is. This may be a selection effect — meaning that we see these worlds because they’re the easiest type to see — but it may also be something that will inevitably occur.

    As huge amounts of mass leave the Sun, they will encounter these giant worlds, all of which have large gravitational fields. Much of the matter that encounters these atmospheres will make a cosmic “splat,” causing the size and masses of these worlds to increase. When all is said and done, Jupiter, Saturn, Uranus and Neptune may all be larger and more massive than they are today.

    5
    While a visual inspection shows a large gap between Earth-size and Neptune-size worlds, the transformation of the Sun into a red giant will increase this disparity. Earth and Mars will lose their atmospheres and potentially even parts of their surfaces, while the gas giants will grow, accreting more and more matter as the Sun expels its outer layers. (LUNAR AND PLANETARY INSTITUTE)

    But the Sun will be so hot and so bright that much of the outer Solar System will be absolutely destroyed. Each of the gas giants has a ringed system; although Saturn’s is the most famous, all four of them have rings. These rings are mostly made of various ices, such as water ice, methane ice, and carbon dioxide. With the extreme energies given off by the Sun, not only will these ices melt/boil away, but the individual molecules will be so energetic that they will be ejected from the Solar System.

    6
    The rings of Neptune, taken with Voyager 2’s wide-angle camera and overexposed. You can see how continuous the rings are in this photo. The rings of Neptune, like the rings of all the gas giants, are made of volatile, icy compounds, and will melt/boil/sublimate away when the Sun becomes a red giant. (NASA / JPL)

    Ditto for water-rich moons around these worlds. Europa’s frozen surface with water-ice beneath it will boil away completely. Same deal for Enceladus, which should see the entire world except for the rock-and-metal core evaporate. Practically all of the moons around Jupiter, Saturn, Uranus and Neptune will see a significant reduction in size, as their atmospheres boil away, their outer layers melt and disappear, and only the rock-and-metal cores of these satellite worlds remain. Some moons, if made completely of volatiles, may wind up extinguished entirely.

    Even the largest, best-known objects from the Kuiper belt aren’t immune to this trouble. Even at their tremendous distances, worlds like Triton, Eris, and Pluto will receive more than four times the energy at their surface that Earth receives today. Their atmospheres and surfaces, currently laden with various types of ices and likely subsurface oceans, will also boil away entirely. When the Sun becomes a red giant and the inner worlds become charred and/or engulfed by the Sun, worlds like Pluto won’t become planets or potentially habitable; they’ll fry. They’ll become a barren core of rock-and-metal, like miniature versions of how Mercury is today.

    7
    The geologic structure beneath the surface of Sputnik Planitia. On Pluto, it is possible that the thinned crust is overlying a liquid water ocean. When the Sun becomes a red giant, all of the outer layers will sublimate and boil away, leaving only the metal/rock core behind. (JAMES T. KEANE)

    For a few tens or hundreds of millions of years, there may be hope for more temperature conditions out in the outer Kuiper belt: about 80-to-100 Earth-Sun distances away. For this brief amount of cosmic time, objects at that distance will receive roughly the same amount of sunlight that Earth does at its surface. It takes a lot more than sunlight to make a habitable world, though; you need enough mass, the right size, and the right ingredients. The Moon and Earth fare very differently for habitability despite receiving practically identical amounts of energy-per-square-meter.

    8
    The orbits of the known Sednoids, along with the proposed Planet Nine. Even with the Sun as a red giant, Planet Nine — whose existence is very controversial to begin with — will not reach sufficient temperatures to become potentially habitable. The other worlds in the Kuiper belt, even the ones at the right distances, are far too small to be interesting from that perspective, too. (K. BATYGIN AND M. E. BROWN ASTRONOM. J. 151, 22 (2016), WITH MODIFICATIONS/ADDITIONS BY E. SIEGEL)

    However, even a hypothetical Planet Nine would be too far away to become habitable, while everything at the right distance is far too small to possibly house life. The Solar System will become a melted catastrophe, with only the stripped cores of planets, moons, and other objects remaining. The gas giants may swell and grow, losing their rings and many of their satellites, but everything else will literally be nothing more than a metal-rich hunk of junk. If you were hoping that these frozen, outer worlds in our Solar System would finally get their chance to shine, you’re in for a big disappointment. When the Sun reaches the end of its life, those worlds, like our hopes for survival, will see everything meaningful about them melt away.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 9:36 am on March 12, 2018 Permalink | Reply
    Tags: , , , , , Carbon-based molecules are a by-product of red giants, Circumstellar envelopes, , , , Red Giant Stars,   

    From University of Hawaii Manoa via COSMOS: “Complex organic compounds from dying stars could be life precursors” 

    U Hawaii

    University of Hawaii Manoa

    COSMOS

    12 March 2018
    Richard A. Lovett

    Lab experiments reveal carbon-based molecules are a by-product of red giants.

    1
    A red giant star – the font, perhaps, of life… QAI Publishing/UIG via Getty Images

    Laboratory experiments designed to recreate conditions around carbon-rich red giant stars have revealed that startlingly complex organic compounds can form in the “circumstellar envelopes” created by stellar winds blowing off from them.

    The carbon is present because nuclear reactions in these dying stars have progressed to the point that much of their initial complement of hydrogen and helium has been converted into heavier elements such as carbon.

    “There is a lot of carbon in these circumstellar envelopes,” says Ralf Kaiser, a physical chemist at the University of Hawaii at Manoa, US.

    In research published in the journal Nature Astronomy, a team led by Kaiser used a high-temperature chemical reactor to simulate conditions inside these circumstellar envelopes.

    The goal, he says, is to demonstrate how complex compounds can be assembled a couple of carbon atoms at a time at temperatures of up to about 1200 degrees Celsius. Previous research found that a host of organic chemicals can indeed be formed, but the new study pushed the process farther, demonstrating that it is possible to create chemicals at least as complex as pyrene, a 16-carbon compound with a structure like four fused benzene rings.

    So far, pyrene is the most complex molecule constructed in this manner, but Kaiser thinks that it might be just the beginning. “We hope when we do further experiments that this can be extended,” he says.

    What this means, he explains, is that circumstellar envelopes might be able to create molecules with 60 or 70 carbons, or even nanoparticle-sized sheets of graphene, a material composed of a larger array of fused rings.

    Such materials, he says, can act as building blocks on which other molecules, such as water, methane, methanol, carbon monoxide, and ammonia can condense as they move away from the star and cool to temperatures as low as minu-263 degrees Celsius. When the resulting chemical stew is exposed to ionising radiation either from nearby sources or galactic cosmic rays, Kaiser says, they can form sugars, amino acids, and dipeptides.

    “These are molecules relevant to the origins of life,” he adds.

    Billions of years ago, such organic-rich particles may have found their way into asteroids that then rained down onto the primordial Earth, endowing us with the precursors for life.

    Pyrene is a member of a family of compounds called polycyclic aromatic hydrocarbons (PAHs), the simplest of which is naphthalene, the primary ingredient of mothballs. Simple PAHs have already been detected in space, but the holy grail, Kaiser says, will be if more complex ones, such as pyrene, are found by NASA’s OSIRIS-REx mission, now en route to asteroid 101955 Bennu, from which it is expected to send back a sample in 2023.

    NASA OSIRIS-REx Spacecraft

    “We do not know what this mission will find,” Kaiser says. But, “if they find carbonaceous materials such as PAHs, then our experiments say how this organic matter can be formed.”

    Humberto Campins, a planetary scientist from Central Florida University, Orlando, Florida, and member of the OSIRIS REx science team, agrees. Studying the chemical makeup of asteroids, he says, doesn’t just tell us about the composition of our own early solar system, but can also reveal information about “pre-solar” compounds.

    “One of the beauties of sample return missions is that the latest analytical techniques for chemical, mineralogical, and isotopic composition can be applied to very small components of the sample, such as pre-solar grains or molecules,” he says.

    “We know that the dust from these kinds of stars gets incorporated into meteorites, so they are absolutely contributing to the compounds that would be present within Bennu,” adds Chris Bennett, also of the University of Central Florida (and a former student of Kaiser’s, although he was not part of the present study team).

    Chris McKay, an astrobiologist at NASA Ames Research Centre in Moffett Field, California, adds that the paper supports the notion that that the universe contains a large amount of carbon in the form of organic molecules. “[That’s] not a new result,” he says, “but [it is] further support for this key idea in astrobiology.”

    Kaiser adds that the finding demonstrates the value of interdisciplinary studies.

    “Most of the scientists dealing with PAHs [in space] are astronomers,” he says. “They are excellent spectroscopists, but by nature, astronomy sometimes lacks fundamental knowledge about chemistry.”

    Laboratory studies are necessary to turn theories for how complex chemicals can form in space from “hand-waving” into something more definitive, he says.

    But the interdisciplinary impact goes beyond astronomy. Pyrene and other PAHs are common pollutants that can be incorporated into dangerous soot particles created by internal combustion engines and other industrial processes.

    Lessons from astrochemistry about how they can be formed, he says, says Kaiser, can therefore have the very practical side effect of helping us develop less-polluting automobile engines.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

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    The University of Hawai‘i System includes 10 campuses and dozens of educational, training and research centers across the Hawaiian Islands. As the public system of higher education in Hawai‘i, UH offers opportunities as unique and diverse as our Island home.

    The 10 UH campuses and educational centers on six Hawaiian Islands provide unique opportunities for both learning and recreation.

    UH is the State’s leading engine for economic growth and diversification, stimulating the local economy with jobs, research and skilled workers.

     
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