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Thread: Could rogue planets and dwarfs have passed though the outer solar system in the past?

  1. #1
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    Could rogue planets and dwarfs have passed though the outer solar system in the past?

    While playing with Universe sandbox I discovered you can throw Jupiter and larger sized object though the outer solar system without any major (visible to me) affect on the planets so long as you don't get closer than either objects hills sphere. While an object's hills sphere radius grows the further you are from the sun, so does the volume of space and hence decreasing the probability of an encounter. Also realise that the effect of passing though another objects hills sphere also depends on the speed at which it occurs.

    Anyway, to the point of my question. My simulation with Universe sandbox doesn't include the huge number of asteroids, comets and other minor bodies in the solar system. Would the passage of a rogue planet or dwarf star have scattered a sufficient number of asteroids etc to have left a statistically verifiable signature? If not, could it be that this type of thing has happened many times in the past and not left any trace.

  2. #2
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    Interesting question! I've done simulations on single passes, and found no perceptible effect if in pre-history a Jupiter Mass rogue passed through the solar system. Now with recent estimates for rogue objects larger than about a quarter of the mass of the Moon being about 100,000 times as many as there are stars, it might be worth doing some statistical analysis to see how many asteroids and KBOs should have disturbed orbits from such encounters, and whether there is a way to tell those differences from perturbations from resonances with existing planets.
    Forming opinions as we speak

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    Quote Originally Posted by antoniseb View Post
    Interesting question! I've done simulations on single passes, and found no perceptible effect if in pre-history a Jupiter Mass rogue passed through the solar system. Now with recent estimates for rogue objects larger than about a quarter of the mass of the Moon being about 100,000 times as many as there are stars, it might be worth doing some statistical analysis to see how many asteroids and KBOs should have disturbed orbits from such encounters, and whether there is a way to tell those differences from perturbations from resonances with existing planets.
    Using the 100,000 figure, then it makes sense that for every 100,000 of these objects that pass through our solar system, 1 star should also pass through. I made a javascript calculator to determine how many times a star passes within a given distance of the sun during a given time period.

    http://orbitsimulator.com/formulas/cse.html

    Plugging in 40 AU (~Pluto's orbit) for distance and 4 billion years for time shows that we can expect 0.0005 stars to pass through our solar system every 4 billion years. Multiplying this by 100,000 gives about 50 objects 1/4 moon mass or greater that have passed through our solar system during the life of the solar system. Since objects with less mass than the Moon probably outnumber Jupiter-mass objects thousands to 1, its not likely that anything Jupiter-mass has ever ventured closer to the Sun than Pluto's orbit.

    The odds may have been higher during the first few hundred million years if the solar system began as part of a star cluster.

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    Quote Originally Posted by tony873004 View Post
    ... I made a javascript calculator to determine how many times a star passes within a given distance of the sun during a given time period. ...
    Excellent! Thanks.
    Forming opinions as we speak

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    Thanks. That's great!
    It kind of answers another question I had.
    Have we ever seen anything (comet or asteroid) that was proven to be of interstellar origin?

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    Quote Originally Posted by antoniseb View Post
    Interesting question! I've done simulations on single passes, and found no perceptible effect if in pre-history a Jupiter Mass rogue passed through the solar system. Now with recent estimates for rogue objects larger than about a quarter of the mass of the Moon being about 100,000 times as many as there are stars, it might be worth doing some statistical analysis to see how many asteroids and KBOs should have disturbed orbits from such encounters, and whether there is a way to tell those differences from perturbations from resonances with existing planets.
    That figure is unsupported by the evidence, but assuming it correct then we can apply previous estimates of the rate of stellar encounters to estimate the rate of encounters with smaller bodies. A&A 379, 634-659 (2001)
    DOI: 10.1051/0004-6361:20011330 Stellar encounters with the solar system estimate a stellar encounter rate of approx. 12 stars per Ma within 1pc. Applying the 1e5 nonsense we get 1e6 1 pc encounters with bodies massiver than a quarter moon per Ma. Rescaling volume and ignoring the effect of solar gravity we get 1 such object within 2000au per megayear or about 4000 since the formation of Earth. That doesn't seem very many and such small bodies would have a negligible effect unless they hit something.

  7. #7
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    Just as the Earth is a very small target compared to the scale of the solar system, so too is the solar system (the outer planets' orbits) a small area compared to just the stellar neighborhood.

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    It's also the same reason particle accelerators have to fire lots stuff at atoms to get reactions... there is lots and lots and lots of empty space in there and most just pass right on through....

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    Quote Originally Posted by Rhaedas View Post
    Just as the Earth is a very small target compared to the scale of the solar system, so too is the solar system (the outer planets' orbits) a small area compared to just the stellar neighborhood.
    Right. Being hit by interstellar debris is one of the things we don't have to worry about.

  10. #10
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    Could rogue planets or dwarfs...? well YES.. but we do not see ANY evidence of such ever have happening..

    The chances are... NO. and the chance of it happening are very slim.

    Any collisions and close passers were all or most certainly from objects of this system..

    Is that what this is really about ?

  11. #11
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    The sun orbits the galaxy once every 230 million years or so.
    It is currently passing though a small spiral arm.

    From http://curious.astro.cornell.edu/que...php?number=402
    "We pass through a major spiral arm about every 100 million years, taking about 10 million years to go through. During the transit, there would be a higher rate of 'nearby' supernova and possibly other so called 'environmental stresses' which could alter the climate of the Earth. "

    How much higher is the probabilities of an encounter while passing though a major spiral arm?
    Also my understanding is that globular clusters also orbit the galactic core. Does the sun pass though those every now and then?
    In "The universe" episode "The search for Cosmic Clusters" they mentioned a cluster than is know to pass though the galactic plane.
    I assume stars and dust block the viability of clusters orbiting with in the galactic plane.

    @astromark
    I was mostly interested that if this had occurred what visible evidence might it leave. (numbers of asteroids in highly elliptical orbits?)
    When the solar system first formed in a cluster, the probability would have been much much higher.

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