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Thread: Astronomy

  1. #1651
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    The SOCIETY for POPULAR ASTRONOMY

    Electronic News Bulletin No. 463 2018 February 18

    GRAVITATIONAL LENS SETS NEW RECORD
    University of Hawaii at Manoa

    Extremely distant galaxies are mostly too faint to be seen, even by the
    largest telescopes. But nature has a solution: gravitational lensing,
    predicted by Einstein and observed many times by astronomers. Now, an
    international team of astronomers has discovered one of the most extreme
    instances of magnification by gravitational lensing. Using the Hubble
    Telescope to survey a sample of huge clusters of galaxies, the team found a
    distant galaxy, eMACSJ1341-QG-1, that is magnified 30 times thanks to the
    distortion of space-time created by the massive 'foreground' galaxy cluster
    dubbed eMACSJ1341.9-2441. The underlying physical effect of gravitational lensing was first confirmed during the solar eclipse of 1919, and can dramatically magnify images of distant celestial sources if a sufficiently massive object lies between the background source and the observers. Galaxy clusters, enormous concentrations of dark matter and hot gas surrounding hundreds or thousands of individual galaxies, all bound by the force of gravity, are valued by astronomers as powerful gravitational lenses. By magnifying the galaxies situated behind them, massive clusters act as natural telescopes that allow scientists to study faint and distant sources that would otherwise be beyond the reach of even the most powerful man-made telescopes. In the present instance, The high magnification of the image provides astronomers with a rare opportunity to investigate the stellar populations of that distant object and, ultimately, to reconstruct its undistorted shape and properties. Although similarly extreme magnifications have been observed before, the discovery sets a record for the magnification of a rare 'quiescent' background galaxy -- one that, unlike our Milky Way, is not forming new stars in giant clouds of cool gas. The team specializes in finding extremely massive clusters that act as natural telescopes and has already discovered many exciting cases of gravitational lensing. This discovery stands out, though, as the huge magnification provided by eMACSJ1341 allows us to study in detail a rare type of galaxy.

  2. #1652
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    I think I understand the concept of Gravitational lensing from the above post.

  3. #1653
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    By magnifying the galaxies situated behind them, massive clusters act as natural telescopes that allow scientists to study faint and distant sources that would otherwise be beyond the reach of even the most powerful man-made telescopes.
    This is not clear to me, how these massive clusters act as magnifying lenses.
    "You can always find something better than death."
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