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  • richardmitnick 6:07 am on June 15, 2017 Permalink | Reply
    Tags: A 3D View of a Supernova Remnant, , , , , , Tycho Supernova Remnant   

    From AAS NOVA: “A 3D View of a Supernova Remnant” 

    AASNOVA

    American Astronomical Society

    14 June 2017
    Susanna Kohler

    1
    A false-color X-ray image by Chandra of the Tycho supernova remnant, first discovered in 1572. [NASA/CXC/Rutgers/J.Warren & J.Hughes et al.]

    NASA/Chandra Telescope


    The Tycho supernova remnant was first observed in the year 1572. Nearly 450 years later, astronomers have now used X-ray observations of Tycho to build the first-ever 3D map of a Type Ia supernova remnant.

    Signs of Explosions

    Supernova remnants are spectacular structures formed by the ejecta of stellar explosions as they expand outwards into the surrounding interstellar medium.

    One peculiarity of these remnants is that they often exhibit asymmetries in their appearance and motion. Is this because the ejecta are expanding into a nonuniform interstellar medium? Or was the explosion itself asymmetric? The best way we can explore this question is with detailed observations of the remnants.

    2
    Histograms of the velocity in distribution of the knots in the X (green), Y (blue) and Z (red) directions (+Z is away from the observer). They show no evidence for asymmetric expansion of the knots. [Williams et al. 2017]

    Enter Tycho

    To this end, a team of scientists led by Brian Williams (Space Telescope Science Institute and NASA Goddard SFC) has worked to map out the 3D velocities of the ejecta in the Tycho supernova remnant. Tycho is a Type Ia supernova — thought to be caused by the thermonuclear explosion of a white dwarf in a binary system that was destabilized by mass transfer from its companion.

    After ~450 years of expansion, the remnant now has the morphological appearance of a roughly circular cloud of clumpy ejecta. The forward shock wave from the supernova, however, is known to have twice the velocity on one side of the shell as on the other.

    To better understand this asymmetry, Williams and collaborators selected a total of 57 knots in Tycho’s ejecta, spread out around the remnant. They then used 12 years of Chandra X-ray observations to measure both the knots’ proper motion in the plane of the sky and their line-of-sight velocity. These two measurements were then combined to build a full 3D map of the motion of the ejecta.

    3
    3D hydrodynamical simulations of Tycho, stopped at the current epoch. These show that both initially smooth (top) and initially clumpy (bottom) ejecta models are consistent with the current observations of the morphology and dynamics of Tycho’s ejecta. [Adapted from Williams et al. 2017]

    Symmetry and Clumps

    Williams and collaborators found that the knots have total velocities that range from 2400 to 6600 km/s. Unlike the forward shock of the supernova, Tycho’s ejecta display no asymmetries in their motion — which suggests that the explosion itself was symmetric. The more likely explanation is a density gradient in the interstellar medium, which could slow the shock wave on one side of the remnant without yet affecting the motion of the clumps of ejecta.

    As a final exploration, the authors attempt to address the origin of Tycho’s clumpiness. The fact that some of Tycho’s ejecta knots precede its outer edge has raised the question of whether the ejecta started out clumpy, or if they began smooth and only clumped during expansion. Williams and collaborators matched the morphological and dynamical data to simulations, demonstrating that neither scenario can be ruled out at this time.

    This first 3D map of a Type Ia supernova represents an important step in our ability to understand these stellar explosions. The authors suggest that we’ll be able to expand on this map in the future with additional observations from Chandra, as well as with new data from future X-ray observatories that will be able to detect fainter emission.

    Citation

    Brian J. Williams et al 2017 ApJ 842 28. doi:10.3847/1538-4357/aa7384

    Related Journal Articles
    See the full article for further references with links

    See the full article here .

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    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 10:46 am on May 18, 2017 Permalink | Reply
    Tags: , , , , , Tycho Supernova Remnant   

    From IAC Lee: ” The Chandra Observatory of NASA found new evidence about the origin of supernovas. The supernova remnant of Tycho” 

    IAC

    Instituto de Astrofísica de Canarias – IAC

    5.18.17
    Manu Garcia‎

    1
    The supernova remnant of Tycho. Credit: NASA / Cxc / Chinese Academy of sciences / f. Lu et al.

    NASA/Chandra Telescope

    This image is an image of the supernova remnant of Tycho, Tycho for short, contains new evidence of what was the mechanism that originated the supernova explosion in the skies of earth 1.572 CE. Tycho originated by a supernova explosion type 1a supernovae, these are used to measure the cosmic distance and the expansion of the universe due to his tremendous starshine.

    X-Rays of medium and low energy is represented in red showing us the remains of the debris from the supernova explosion, x-Rays of high-Energy Blue represented reveal the shockwave of the blast, a shell of high-energy electrons. Also shown in bottom left region of tycho a blue bow of x-Ray emission. Several lines of evidence supporting the conclusion that this bow is due to a shock wave created when a white dwarf exploded and blew the surface material from a companion star nearby. Previously, the studies with optical telescopes have revealed a star within the remnant that is moving much more quickly than their neighbours, indicating that it could be the companion of the white dwarf that erupted giving the supernova explosion a cosmic kick to this star who made That displace so abruptly.

    Other details of the arch support the idea of who was cast out away from the companion star. For example, the emission of x-Ray shows a remnant of the “Shadow” apparent next to the arch, consistent with the blocking of the remains of the explosion by the cone of expansion of the material he was robbed of his partner. This shadow is more obvious in x-Ray very high energy showing traces of iron.

    This evidence supported a popular scenario to be triggered a type ia supernova, where a white dwarf extracted material from a companion star “normal”, or similar to the sun, until it produces a thermonuclear explosion. In the other main competitive theory, happens a fusion of two white dwarfs, and in this case, no star partner or evidence of material ripped from a partner must exist. Both scenarios can happen really under different conditions, but the final result of Chandra of tycho supports the previous one.

    The shape of a bow is different from any other feature seen in the remnant. Other features inside the remnant include the stripes announced recently that have a different way and you think to be features in the wave of external explosion caused by the acceleration of the cosmic ray.

    See the full article here.

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    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

     
  • richardmitnick 8:03 pm on May 12, 2016 Permalink | Reply
    Tags: , , , Tycho Supernova Remnant   

    From Chandra: Tycho’s Supernova Remnant from Chandra 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    1
    Credit X-ray: NASA/CXC/GSFC/B.Williams et al; Optical: DSS
    Release Date May 12, 2016

    For the first time, a movie has been made of the evolution of Tycho’s supernova remnant.

    This sequence includes X-rays observations from Chandra spaced out over a decade and a half.

    Tycho belongs to a class of supernovas used to measure the expansion of the Universe so the details of these explosions are very important.

    By combining the Chandra data with 30 years worth of observations with the VLA, scientists have learned new things about this remnant and its history.


    Access mp4 video here .
    Video released in 2011

    When the star that created this supernova remnant exploded in 1572, it was so bright that it was visible during the day. And though he wasn’t the first or only person to observe this stellar spectacle, the Danish astronomer Tycho Brahe wrote a book about his extensive observations of the event, gaining the honor of it being named after him.

    In modern times, astronomers have observed the debris field from this explosion – what is now known as Tycho’s supernova remnant – using data from NASA’s Chandra X-ray Observatory, the NSF’s Karl G. Jansky Very Large Array (VLA) and many other telescopes.

    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, New Mexico.
    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, New Mexico

    Today, they know that the Tycho remnant was created by the explosion of a white dwarf star, making it part of the so-called Type Ia class of supernovas used to track the expansion of the Universe.

    Since much of the material being flung out from the shattered star has been heated by shock waves – similar to sonic booms from supersonic planes – passing through it, the remnant glows strongly in X-ray light. Astronomers have now used Chandra observations from 2000 through 2015 to create the longest movie of the Tycho remnant’s X-ray evolution over time, using five different images. This shows the expansion from the explosion is still continuing about 450 years later, as seen from Earth’s vantage point roughly 10,000 light years away.

    By combining the X-ray data with some 30 years of observations in radio waves with the VLA, astronomers have also produced a movie, using three different images. Astronomers have used these X-ray and radio data to learn new things about this supernova and its remnant.

    The researchers measured the speed of the blast wave at many different locations around the remnant. The large size of the remnant enables this motion to be measured with relatively high precision. Although the remnant is approximately circular, there are clear differences in the speed of the blast wave in different regions. The speed in the right and lower right directions is about twice as large as that in the left and the upper left directions. This difference was also seen in earlier observations.

    This range in speed of the blast wave’s outward motion is caused by differences in the density of gas surrounding the supernova remnant. This causes an offset in position of the explosion site from the geometric center, determined by locating the center of the circular remnant. The astronomers found that the size of the offset is about 10% of the remnant’s current radius, towards the upper left of the geometric center. The team also found that the maximum speed of the blast wave is about 12 million miles per hour.

    Offsets such as this between the explosion center and the geometric center could exist in other supernova remnants. Understanding the location of the explosion center for Type Ia supernovas is important because it narrows the search region for a surviving companion star. Any surviving companion star would help identify the trigger mechanism for the supernova, showing that the white dwarf pulled material from the companion star until it reached a critical mass and exploded. The lack of a companion star would favor the other main trigger mechanism, where two white dwarfs merge causing the critical mass to be exceeded, leaving no star behind.

    The significant offset from the center of the explosion to the remnant’s geometric center is a relatively recent phenomenon. For the first few hundred years of the remnant, the explosion’s shock was so powerful that the density of gas it was running into did not affect its motion. The density discrepancy from the left side to the right has increased as the shock moved outwards, causing the offset in position between the explosion center and the geometric center to grow with time. So, if future X-ray astronomers, say 1,000 years from now, do the same observation, they should find a much larger offset.

    A paper* describing these results has been accepted for publication in The Astrophysical Journal Letters and is available online*. The authors are Brian Williams (NASA’s Goddard Space Flight Center), Laura Chomiuk (Michigan State University), John Hewitt (University of North Florida), John Blondin (North Carolina State University), Kazimierz Borkowski (NCSU), Parviz Ghavamian (Towson University), Robert Petre (GSFC), and Stephen Reynolds (NCSU).

    *Science paper:
    An X-ray and Radio Study of the Varying Expansion Velocities in Tycho’s Supernova Remnant

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
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