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Sirius - habitable orbit? (link)

  1. Jun 20, 2005 #1
    I thought this was an interesting idea, it's an animation of a theoretically habitable orbit around Sirius A.

    It's something *I* didn't expect. I always thought any planet pretty much anywhere in orbit of Sirius A would get baked by X-Rays from Sirius B every now and then.
    This site contends that that's not neccessarily true if a planet was found to have the right orbit around Sirius A.

    Any thoughts?

    The link:

  2. jcsd
  3. Jun 20, 2005 #2


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    I get a different result. Using that website's data for Sirius A & Sirius B mass, semi-major axes, and eccentricity, I find that a planet orbiting 4.76 AU from Sirius A is ejected from the system after only 1-2 orbits.

    If I put the planet 4.76 AU from the AB barycenter rather than from Sirius A, it doesn't even complete 1 orbit.

    Attached Files:

  4. Jun 23, 2005 #3
    If by _habitable_ you imply will be able to support life, then I think okay - if your calcs are right. If you imply has life, then I think difficult if not impossible, because sirius A is too young a system, and Sirius B will have gone through red giant phase relatively recently, disrupting all hopes for life.

    I digress from your dynamics, sorry!
  5. Jun 23, 2005 #4


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    what do you think (habitable or not) about this system 15 lightyears away?


    three planets have been detected
    the inner one is too hot
    the outer one is too cold
    but the middle one would be roughly same average temp as earth

    (I guess it would need to have satellites like the jovian system because the main planet is jupiter-size, but anyway temp seems right)

    for data relevant to temperature, see
  6. Jun 24, 2005 #5
    <<<three planets have been detected
    the inner one is too hot
    the outer one is too cold
    but the middle one would be roughly same average temp as earth>>>

    If that middle one is a _rocky_ planet then there is every hope for life. So they should steer the SETI dishes in this direction now...
  7. Jun 28, 2005 #6


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    If it's 'too hot', then not much hope. However, if it's 'too cold', there may be some ... the Earth gets hotter as you go deeper into the crust, and that heat has nothing to do with photons from the Sun. Too, we now know life is quite comfortable for a number of bacteria and archaea (and maybe even some eukaryotes?) ... even 20 km down, in 'solid' rock. Maybe in some Hadean pool, deep beneath the surface of Gliese 876c ...
  8. Jul 5, 2005 #7
    Supposing 4 a moment...

    That there WAS not only a habitable, but inhabited world in orbit of Sirius A.
    (This is for a SF story, so a bit of a stretch for artistic license here)
    Assuming that this world did lay in the orbit proposed in the link of my orig post i.e. :


    1) What would Sirius A look like from the surface of that world (color, size, brightness, etc.) if it were a more or less Earth like world?

    2) What would Sirius B look like?

    3) Would Sirius B have a strong influence of the seasons of such a world? Or would its influence in that regard be all but unnoticeable?
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