English subtitles for clip: File:The Planet Around Beta Pictoris Makes Waves.webm

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[Music](the subtitle comes from svs.gsfc.nasa.gov)

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[Music]

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[Music]

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Erika Nesvold: Beta Pictoris is a star about 60 light years from the Earth.

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And it's surrounded by this huge disk of chunks of rock and ice

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that we call a debris disk. Marc Kuchner: Inside that disk is

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a central clearing in the larger planetesimals and inside that central

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clearing is a planet more massive than any in our solar system.

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Erika Nesvold: We see the Beta Pictoris debris disk edge-on, so we just see the

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thin strip of it from the edge. But there's an interesting feature that

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we can see just from that edge-on view. Marc Kuchner: When we view Beta Pictoris at

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longer wavelengths, people claim that there is a "warp" in the center of the

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disk. At shorter wavelengths, it looks more like an "X."

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And we haven't really understood until now, how those patterns were related.

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But Erika Nesvold and I created a new kind of 

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model, which shows us the connection between those patterns. Erika Nesvold: Our model is called

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SMACK, which stands for the Super-particle Method Algorithm for 

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Collisions in Kuiper Belts. We're creating a virtual solar system

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inside the computer, and by tweaking the parameters of the

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system, we can control what this virtual debris disk looks like.

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Then we can compare our results to the actual images of the debris

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disk we see and understand how the planet could be creating these

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different shapes in the disk. Marc Kuchner: The model painted one picture of Beta

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Pictoris that showed us the origin of the "X" pattern, the origin

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of the warp, and also a bunch of other details about the system.

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Erika Nesvold: Our simulation is the first model that can capture

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the 3D structure of the disk, as well as the collisions that are

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occurring between the planetesimals in the disk. And our simulation is the 

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first model that can explain these multiple different features that we 

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observe when we look at the Beta Pictoris Disk. So if we look at our simulation

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results edge-on--the same way that we see the real Beta Pictoris disk--

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then we see this warp structure that's created because the planet is

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orbiting tilted with respect to the disk. If we look at our

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simulation results face-on--which is a way we can't see the real disk--

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then this face-on simulation shows this spiral

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density structure of the planetesimals. And this spiral is created

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because the planet is on an eccentric orbit. It's not a perfect circle, it's an ellipse.

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When the spiral created by the eccentricity of the planet

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intersects with that vertical wave from the inclination of the 

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planet, the collisions are enhanced in some places and 

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damped out in others, which creates this clumpy collision structure.

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Marc Kuchner: If you look at our model in cross-section, you can see the crests and

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troughs of the wave where the collisions are enhanced. Like and ocean

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wave, in front of the wave it's calm, but then the crest comes

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along and lifts the planetesimals out of the plane. And then there's a trough

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and then the wave starts wrapping around tighter and tighter

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and then it's almost like foam on the backside of the wave. The planetesimals get all

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stirred up and start colliding with one another and breaking into dust.

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We've learned so much about Beta Pictoris over the years

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but all the little pieces of evidence didn't seem to fit together before.

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This model has tied together in a nice, neat

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package, the story of Beta Pictoris and its planet.

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Erika Nesvold: In the future, we'll be able to use our SMACK models to 

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study other debris disk systems and use our observations of

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those disks to predict the presence exoplanets that we

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otherwise wouldn't be able to detect.

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[Beeping]

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[Beeping]

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[Beeping]