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Re: [sct-user] Re: M42 Emission Question

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  • John Mahony
    ... If the gas is dense enough, the gas could be partially shielding gas that s further from the trap stars, so the brightness would fall off faster than
    Message 1 of 17 , Apr 1, 2007
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      --- "ancient.sull" <ancient.sull@...> wrote:

      > --- In sct-user@yahoogroups.com, "Leo Taylor" <leotaylor@...> wrote:
      > > I not qualified to address the cosmology of the brightness gradient,
      > > though I suspect it is proportional to the distance from the
      > > illuminating star.
      >
      > That was my question (whcih I didn't express very clearly). The
      > brightness decrease is _not_ just proportional to distance from the
      > core. There is a very bright area near the core, which is fairly close
      > to the same brightness, then a sharp edge/sharp drop off and beyond
      > that the brightness decreases further, but more proportional to
      > distance.
      >
      > Does anyone else see that edge? Is that a real difference in the
      > density of gas in the cloud or an effect of excitation of the gas which
      > is not inversely proportional to the square of the distance?

      If the gas is dense enough, the gas could be partially shielding gas that's
      further from the trap stars, so the brightness would fall off faster than
      inverse square.

      -John



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    • wrhamblen@comcast.net
      The dark area of M42 is known as the Fish Mouth and is dust obscuring part of the emission nebula. The brightest area of M42 is known as the Huygenian Region.
      Message 2 of 17 , Apr 2, 2007
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        The dark area of M42 is known as the Fish Mouth and is dust obscuring part
        of the emission nebula. The brightest area of M42 is known as the
        Huygenian Region. It is pretty bright. You can crank up the power
        visually to see small details.

        Bud

        On Wed, 28 Mar 2007, Tom Rauschenbach wrote:

        > On Wednesday 28 March 2007 18:58, ancient.sull wrote:
        >> In looking at/imaging M42 I see a sharp, sudden decrease in
        >> brightness a short way from the Trapezium. I.e. (in images) there a
        >> _very_ bright area of the cloud near (within maybe 2-3 times the size
        >> of the trapezium itself) then the gas brightness becomes sharply much
        >> less (and after that continues for a long long way only slowly
        >> decreasing in brightness).
        >>
        >
        >
        > I see it visually and in my CCD camera and in my Webcam. I assumed it was
        > real and was an indication that my image processing technique was not as good
        > as it needed to be.
        >
        > I can't get any nebulosity beyond the immediate area of the Trapezuim without
        > seriously over exposing that central core.
        >
        > Be aware that I am a total newbie, but your experience matches mine.
        >
        >
        >
        >
        >
        > --
        > "The first responsibility of a leader is to define reality. The last is to
        > say thank you. In between, the leader is a servant."
        > [Max De Pree]
        >
        >
        > Visit the sct-user home page at:
        >
        >
        >
        > http://members.aol.com/RMOLLISE/index4.html
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        >
        >
        >
      • ancient.sull
        ... part ... Ah! That sounds like what I am looking (part does look like a fish s mouth). Thanks Drew S.
        Message 3 of 17 , Apr 4, 2007
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          --- In sct-user@yahoogroups.com, wrhamblen@... wrote:
          >
          > The dark area of M42 is known as the Fish Mouth and is dust obscuring
          part
          > of the emission nebula. The brightest area of M42 is known as the
          > Huygenian Region. It is pretty bright. You can crank up the power
          > visually to see small details.
          >
          > Bud

          Ah! That sounds like what I am looking (part does look like a fish's
          mouth).

          Thanks

          Drew S.
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