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Re: [comets-ml] C/2011 L4's (PanSTARRS) Tail In Early 2013?

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  • jbortle@aol.com
    Further addressing the question of the appearance of C/2011 L4 s dust tail, in examining the viewing circumstance for this comet during its coming apparition
    Message 1 of 1 , Jul 24, 2012
      Further addressing the question of the appearance of C/2011 L4's dust tail,
      in examining the viewing circumstance for this comet during its coming
      apparition an interesting situation is apparent. For several weeks either side
      of the perihelion passage any dust tail will be presented nearly face-on
      to the Earth. This will cause its appearance to be essentially undistorted
      by projection circumstances and therefore displaying the maximum degree of
      real curvature.

      Thus, how the dust tail will look as viewed from Earth with the nakedeye
      can have many potential possibilities totally dependent on the distribution
      of mass/ejection velocities of dust particles from the nucleus. Likewise,
      if there happens to be a very broad distribution of these dust particle
      sizes, then the tail is likely to be very wide and have a lower surface
      brightness than might be otherwise anticipated for a comet of such high intrinsic
      brightness. To a degree, this was the case with P/Halley in 1986 shortly
      after its perihelion passage. Conversely, if a comet's dust tail happens to
      be seen nearly edge-on it can be very bright indeed, as many here are
      probably already aware.

      Regardless, a few things do seem fairly certain. Any nakedeye dust tail
      that is seen in all likelihood will be rather dramatically curved and lag the
      direction of the ion tail (the ERV) by many degrees. I would even speculate
      that Comet PANSTARRS' appearance next February/March - assuming that it
      evolves as currently hoped - could perhaps be somewhat like that of Comet
      Donati in September of 1858 (although not of such great length), if the range
      in dust particle size is fairly typical.

      J.Bortle



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