About Trappist-1

Discussion in 'Astronomy, Exobiology, & Cosmology' started by DaveC426913, Feb 27, 2017.

  1. DaveC426913 Valued Senior Member

    Messages:
    6,964
    Thanks yeah.
    Some of those comments I paraphrased from the announcement with little in the way of context.
     
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  3. nebel Registered Senior Member

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    370
    no, I am looking at a simpler bode-like radius analisis, planets b, d,e,f,g and h are within ~4 % of a grid that has .0008 AU spacings. Planet c is within 6.7% of halfway between it's neighbours, and there is no planet in the last gap between g and h, so:
    you have a pattern of a reasonable fit in the pattern of .0004 AU;-- b,c&d; .0008 AU: b,d,e,f,g,--; and .016 between g,f .*
    * numbers are given as in the theoretical .004, .008 and .016 grid. namely .0118; .o201 .0282 .o365 .0446 .o61 AU in equal .008 AU spacings.
    It looks clear on my measuring stick. and these simple orbital radius relations will translate into related velocities, timings.
    Janus got it right with his/her avatar, it is 5 equally spaced circling planets, plus 1 in a half and another in a doubling spacing. octaves all the way.
     
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  5. nebel Registered Senior Member

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    In the solar system. Earth and Jupiter are the ones most closely conforming to a bode-type sequence.
    in Trappist-1,
    e,: .7 % has deviation
    f,: 1.4 % "
    g,: 1.6 % "
    so if our home is any indication, life and stabilizing would be concentrated in those three, as Earth and Jupiter provide life and stability here.
     
    Last edited: Mar 7, 2017
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  7. Janus58 Valued Senior Member

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    1,801
    Here's a couple of images that give an idea of how outer planets could appear to someone on planets e, f and g.

    The first one shows how the apparent sizes of the planets change over the course of a synodic period. The apparent sizes are shown how they change over equal time periods. The red lines represent the rising and setting horizons for someone at the center of the night-side. These would shift as you moved towards one day-night terminator or the other.
    The first three line are Planets f,g and h as viewed from e. The time passage between images for each line is as follows:
    f: 14.46 hrs (total synodic period 18.07 days)
    g: 9.64 hrs (total synodic period 12.05 days)
    h: 7.02 hrs (total synodic period 8.78 days)

    The next two lines are g and h as viewed from f
    g: 28.92 hrs (total synodic period 36.15 days)
    h: 13.65 hrs (total synodic period 17.06 days)

    Then we have h as viewed from g
    h: 25.8 hrs (total synodic period 32.31 days)

    Last, we have the Moon's apparent size as seen from the Earth for comparison.

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    The spacing between the images does not represent the actual movement of these planets across the sky during the time intervals. For that we have the next image. It shows the planet's relative position with respect to horizons and zenith for our hypothetical mid night-side observer. The time passage between images are the same equal time periods as in the first image. Here we note that the apparent motion is at its greatest near the zenith and decreases as you near the horizons.

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