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Planet swapping

  1. Dec 19, 2004 #1
    "Computer simulations show a close encounter with a passing star about 4 billion years ago may have given our solar system its abrupt edge and put small, alien worlds into distant orbits around our sun."


    That's interesting. I've heard of people that exchage marbles, but exchanging planets seems more serious stuff :biggrin:
  2. jcsd
  3. Dec 19, 2004 #2


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    Actually, you don't need a supercomputer to do these kinds of simulations. I used a program I wrote called Gravity Simulator (www.gravitysimulator.com) to reproduce an experiment done by astronomers using a supercomputer to explore the orgin of Sedna's orbit. I got the exact same results they did.

    Astronomers Alessandro Morbidelli and Harold F. Levison investigated Sedna's origins by performing numerical integrations using the Swift_rmvs3 orbit integrator to explore the idea that Sedna may have once been gravitationally bound to another star or brown dwarf, and stripped away by the Sun, where it entered a highly eccentric solar orbit.

    Using Gravity Simulator, I reproduced their experiment. Morbidelli and Levison set up the following starting conditions: The visiting brown dwarf has a mass of 0.05 solar masses. It is has a velocity of 1 km/s relative to the Sun at infinity. Its approach distance to the Sun is 200 AU. The brown dwarf has a disk of test particles orbiting it in the plane of the encounter at random distances between 20-100 AU.

    In Morbidelli and Levison's experiment, 44% of the Brown Dwarf's objects were captured into Solar orbit. In Gravity Simulator, consistant with Morbidelli and Levison's experiment, 8 of 20 objects were captured into Solar orbit.

    As the simulation begins, the Brown Dwarf system is closing in on the Solar System
    from a distance of just under 1 trillion kilometers.

    The Brown Dwarf system closes its distance to the Sun.
    The green planet around the Sun is Neptune.

    As the Brown Dwarf system gets even closer,
    the Sun's gravity starts distorting the system.

    The Sun sends a strong gravitational tidal force through the Brown Dwarf system.
    Objects outside the Brown Dwarf's Hill sphere are stripped away.
    Some enter a Solar orbit.

    After all the dust has settled, 8 objects which originally orbited the Brown Dwarf
    are now orbiting the Sun, some in Sedna-like orbits.
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