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  • richardmitnick 3:09 pm on September 13, 2015 Permalink | Reply
    Tags: , , Binary star, Queens U   

    From Queens: “Stellar discovery by Queen’s researcher” 

    Queens U bloc

    Queens University

    September 11, 2015
    Anne Craig

    PhD candidate Matt Shultz discovers massive binary star with unique properties.

    1
    The polarity of the star’s surface magnetic field, north or south, is indicated by red and blue respectively. Yellow lines indicate the magnetic field lines running from the stellar surfaces. Credit: Visualisation courtesy of Volkmar Holzwarth, KIS, Freiburg

    PhD candidate Matt Shultz has discovered the first massive binary star, epsilon Lupi, in which both stars have magnetic fields. A binary star is a star system consisting of two or more stars, orbiting around their common centre of mass.

    For the past few years, the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) collaboration, formed to study the magnetic properties of close binaries, has been trying to find such an object. They have now discovered one using the Canada-France-Hawaii Telescope [CFHT].

    CFHT
    CFHT Interior
    CFHT

    “The origin of magnetism amongst massive stars is something of a mystery,” says Mr. Shultz (Physics, Engineering Physics and Astronomy), “and this discovery may help to shed some light on the question of why these stars have magnetic fields.”

    In cool stars, such as the Sun, magnetic fields are generated by a convection in the outer portion of the star. However, there is no convection in the outer layers of massive star, so there is no support for a magnetic dynamo. Nevertheless, approximately 10 per cent of massive stars have strong magnetic fields.

    Two explanations have been proposed for the origin of massive star magnetic fields, both variants on the idea of a so-called “fossil” magnetic field, which is generated at some point in the star’s past and then locked in to the star’s outer portion.

    The first hypothesis is that the magnetic field is generated while the star is being formed; the second is that the magnetic field originates in dynamos driven by the violent mixing of stellar plasma when the two stars in a close binary merge.

    “This discovery doesn’t change the basic statistics that the BinaMIcS collaboration has assembled,” says Mr. Shultz, “and we still don’t know why there are so few magnetic, massive stars in close binaries.”

    The research shows the strengths of the magnetic fields are similar in the two stars, however, their magnetic axes are anti-aligned, with the south pole of one star pointing in approximately the same direction as the north pole of the other.

    “We’re not sure why that is yet, but it probably points to something significant about how the stars are interacting with one another. We’ll need to collect more data.”

    The research was published in the Monthly Notices of the Royal Astronomical Society.

    See the full article here .

    Please help promote STEM in your local schools .

    STEM Icon

    Stem Education Coalition

    Queens U Campus

    Queen’s University is a community, 170+ years of tradition, academic excellence, research, and beautiful waterfront campus made of limestone buildings and modern facilities. But more than anything Queen’s is people.

    We are researchers, scholars, artists, professors and students with an ambitious spirit who want to develop ideas that can make a difference in the world. People who imagine together what the future could be and work together to realize it.

    Queen’s is one of Canada’s oldest degree-granting institutions, and has influenced Canadian higher education since 1841 when it was established by Royal Charter of Queen Victoria.

    Located in Kingston, Ontario, Canada, it is a mid-sized university with several faculties, colleges and professional schools, as well as the Bader International Study Centre located in Herstmonceux, East Sussex, United Kingdom.

    Queen’s balances excellence in undergraduate studies with well-established and innovative graduate programs, all within a dynamic learning environment.

     
  • richardmitnick 8:40 pm on September 10, 2015 Permalink | Reply
    Tags: , , , Queens U   

    From Queens: “Monitoring magnetospheres” 

    Queens U bloc

    Queens University

    September 10, 2015
    Anne Craig

    Queen’s researcher works to debunk the theory behind massive stars.

    Queen’s University PhD student Matt Shultz is researching magnetic, massive stars, and his research has uncovered questions concerning the behaviour of plasma within their magnetospheres.

    1
    This image shows the magnetosphere of a massive star. (Image by Richard Townsend)

    Drawing upon the extensive dataset assembled by the international Magnetism in Massive Stars (MiMeS) collaboration, led by Mr. Shultz’s supervisor, Queen’s professor Gregg Wade, along with some of his own observations collected with both the Canada-France-Hawaii Telescope [CFHT] and the European Southern Observatory’s Very Large Telescope, Mr. Shultz is conducting the first systematic population study of magnetosphere-host stars.

    CFHT
    CFHT Interior
    CFHT

    ESO VLT Interferometer
    ESO VLT Interior
    ESO VLT

    “All massive stars have winds: supersonic outflows of plasma driven by the stars’ intense radiation. When you put this plasma inside a magnetic field you get a stellar magnetosphere,” explains Mr. Shultz (Physics, Engineering Physics and Astronomy). “Since the 1980s, theoretical models have generally found that the plasma should escape the magnetosphere in sporadic, violent eruptions called centrifugal breakout events, triggered when the density of plasma grows beyond the ability of the magnetic field to contain.

    “However, no evidence of this dramatic process has yet been observed, so the community has increasingly been calling that narrative into question.”

    Before now, obvious disagreements with theory had been noted primarily for a single, particularly well-studied star. Studying the full population of magnetic, massive stars with detectable magnetospheres, Mr. Shultz has determined that the plasma density within all such magnetospheres is far lower than the limiting value implied by the centrifugal breakout model. This suggests that plasma might be escaping gradually, maintaining magnetospheres in an essentially steady state.

    “We don’t know yet what is going on,” says Mr. Shultz. “But, when centrifugal breakout was first identified as the most likely process for mass escape, only the simplest diffusive mechanisms were ruled out. Our understanding of space plasmas has developed quite a bit since then. We now need to go back and look more closely at the full range of diffusive mechanisms and plasma instabilities. There are plenty to choose from: the real challenge is developing the theoretical tools that will be necessary to test them.”

    Mr. Shultz is presenting his research at the Canadian Astronomical Society Conference at McMaster University.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Queens U Campus

    Queen’s University is a community, 170+ years of tradition, academic excellence, research, and beautiful waterfront campus made of limestone buildings and modern facilities. But more than anything Queen’s is people.

    We are researchers, scholars, artists, professors and students with an ambitious spirit who want to develop ideas that can make a difference in the world. People who imagine together what the future could be and work together to realize it.

    Queen’s is one of Canada’s oldest degree-granting institutions, and has influenced Canadian higher education since 1841 when it was established by Royal Charter of Queen Victoria.

    Located in Kingston, Ontario, Canada, it is a mid-sized university with several faculties, colleges and professional schools, as well as the Bader International Study Centre located in Herstmonceux, East Sussex, United Kingdom.

    Queen’s balances excellence in undergraduate studies with well-established and innovative graduate programs, all within a dynamic learning environment.

     
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