Star’s close approach 70,000 years ago pinned to cometary orbits


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Astronomers now think they have pinned the orbits of about 340 comets to another star’s close approach to our solar system 70,000 years ago.

About 70,000 years ago, when the human species was already on Earth, a small reddish star approached our solar system and gravitationally disturbed comets and asteroids. Astronomers from the Complutense University of Madrid and the University of Cambridge have verified that the movement of some of these objects is still marked by that stellar encounter. At a time when modern humans were beginning to leave Africa and the Neanderthals were living on our planet, Scholz’s star – named after the German astronomer who discovered it – approached less than a light-year from the Sun. Nowadays it is almost 20 light-years away, but 70,000 years ago it entered the Oort cloud, a reservoir of trans-Neptunian objects located at the confines of the solar system.

This discovery was made public in 2015 by a team of astronomers led by Professor Eric Mamajek of the University of Rochester (USA). The details of that stellar flyby, the closest documented so far, were presented in The Astrophysical Journal Letters.

Now two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time the nearly 340 objects of the solar system with hyperbolic orbits (very open V-shaped, not the typical elliptical), and in doing so they have detected that the trajectory of some of them is influenced by the passage of Scholz´s star.

It is likely that the close approach influenced a lot more objects, many of which might not have yet arrived in the inner solar system. Moreover, their computer models suggest that the star might have come closer to the Sun than 0.6 light years.

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8 comments

  • Localfluff

    It seems strange that such a very nearby star wasn’t discovered until a few years ago. A huge ball of plasma fusion nuking its way through billions of years, still almost invisible in our neighborhood. Is something else hiding out there?

  • geoffc

    That implies it is doing 1/3500th of light speed. Which is about 85 Km/s. 85,000m/s. Still faster than any human probe. Voyager is at 35,000 I think.

    Be fun to be able to accelerate a star even a small one to that kind of speed. Hmmm, how much energy would that take? (Way too much!)

  • Localfluff

    @geoffc Just 17 km/s, I’m afraid. And New Horizons is slower.

    Here is a graph that shows the huge influence of gravity assists on the Voyagers’ speed from the Sun. The fastest star known (to me) moves at a speed of 1,200 km/s relative to the Milky Way center and are concluded to be intergalactic. Just a couple of thousand years from Andromeda at that velocity.

  • Localfluff

    Well, please disregard my fake math in the post above. “Hyper”velocity stars are much more potent. Moving at real fractions of the speed of light. Or a thousand times faster than Voyager now leaving the building.

  • ken anthony

    It is a wondrous thing to think about.

  • Localfluff

    If a foreign star raced through our solar system at hypervelocity speeds, it would shake the Earth. And change our calendar. But at 1/10 of the speed of light, such a star would be “here” as in planetary distances, only for hours. Looking at distances and stuff, one realizes that this never has and never will happen.

  • wayne

    “How fast are we moving through the universe?”
    https://youtu.be/ZX0zcEZnIsA
    (2:03)

  • pzatchok

    I wonder if we could gravity assist a colony ship up to a speed fast enough to use something like this as the next step to getting to a viable solar system?

    Obviously this one is way to far away now.

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