WEBVTT FILE 1 00:00:00.020 --> 00:00:04.040 [Music] 2 00:00:04.060 --> 00:00:08.060 [Music] 3 00:00:08.080 --> 00:00:12.120 [Music] 4 00:00:12.140 --> 00:00:16.160 Erika Nesvold: Beta Pictoris is a star about 60 light years from the Earth. 5 00:00:16.180 --> 00:00:20.230 And it's surrounded by this huge disk of chunks of rock and ice 6 00:00:20.250 --> 00:00:24.330 that we call a debris disk. Marc Kuchner: Inside that disk is 7 00:00:24.350 --> 00:00:28.420 a central clearing in the larger planetesimals and inside that central 8 00:00:28.440 --> 00:00:32.440 clearing is a planet more massive than any in our solar system. 9 00:00:32.460 --> 00:00:36.520 Erika Nesvold: We see the Beta Pictoris debris disk edge-on, so we just see the 10 00:00:36.540 --> 00:00:40.600 thin strip of it from the edge. But there's an interesting feature that 11 00:00:40.620 --> 00:00:44.660 we can see just from that edge-on view. Marc Kuchner: When we view Beta Pictoris at 12 00:00:44.680 --> 00:00:48.670 longer wavelengths, people claim that there is a "warp" in the center of the 13 00:00:48.690 --> 00:00:52.730 disk. At shorter wavelengths, it looks more like an "X." 14 00:00:52.750 --> 00:00:56.740 And we haven't really understood until now, how those patterns were related. 15 00:00:56.760 --> 00:01:00.800 But Erika Nesvold and I created a new kind of 16 00:01:00.820 --> 00:01:04.860 model, which shows us the connection between those patterns. Erika Nesvold: Our model is called 17 00:01:04.880 --> 00:01:08.890 SMACK, which stands for the Super-particle Method Algorithm for 18 00:01:08.910 --> 00:01:12.930 Collisions in Kuiper Belts. We're creating a virtual solar system 19 00:01:12.950 --> 00:01:16.960 inside the computer, and by tweaking the parameters of the 20 00:01:16.980 --> 00:01:21.010 system, we can control what this virtual debris disk looks like. 21 00:01:21.030 --> 00:01:25.030 Then we can compare our results to the actual images of the debris 22 00:01:25.050 --> 00:01:29.050 disk we see and understand how the planet could be creating these 23 00:01:29.070 --> 00:01:33.140 different shapes in the disk. Marc Kuchner: The model painted one picture of Beta 24 00:01:33.160 --> 00:01:37.150 Pictoris that showed us the origin of the "X" pattern, the origin 25 00:01:37.170 --> 00:01:41.200 of the warp, and also a bunch of other details about the system. 26 00:01:41.220 --> 00:01:45.220 Erika Nesvold: Our simulation is the first model that can capture 27 00:01:45.240 --> 00:01:49.260 the 3D structure of the disk, as well as the collisions that are 28 00:01:49.280 --> 00:01:53.340 occurring between the planetesimals in the disk. And our simulation is the 29 00:01:53.360 --> 00:01:57.440 first model that can explain these multiple different features that we 30 00:01:57.460 --> 00:02:01.460 observe when we look at the Beta Pictoris Disk. So if we look at our simulation 31 00:02:01.480 --> 00:02:05.500 results edge-on--the same way that we see the real Beta Pictoris disk-- 32 00:02:05.520 --> 00:02:09.540 then we see this warp structure that's created because the planet is 33 00:02:09.560 --> 00:02:13.590 orbiting tilted with respect to the disk. If we look at our 34 00:02:13.610 --> 00:02:17.630 simulation results face-on--which is a way we can't see the real disk-- 35 00:02:17.650 --> 00:02:21.730 then this face-on simulation shows this spiral 36 00:02:21.750 --> 00:02:25.770 density structure of the planetesimals. And this spiral is created 37 00:02:25.790 --> 00:02:29.810 because the planet is on an eccentric orbit. It's not a perfect circle, it's an ellipse. 38 00:02:29.830 --> 00:02:33.880 When the spiral created by the eccentricity of the planet 39 00:02:33.900 --> 00:02:37.970 intersects with that vertical wave from the inclination of the 40 00:02:37.990 --> 00:02:42.060 planet, the collisions are enhanced in some places and 41 00:02:42.080 --> 00:02:46.110 damped out in others, which creates this clumpy collision structure. 42 00:02:46.130 --> 00:02:50.180 Marc Kuchner: If you look at our model in cross-section, you can see the crests and 43 00:02:50.200 --> 00:02:54.210 troughs of the wave where the collisions are enhanced. Like and ocean 44 00:02:54.230 --> 00:02:58.240 wave, in front of the wave it's calm, but then the crest comes 45 00:02:58.260 --> 00:03:02.290 along and lifts the planetesimals out of the plane. And then there's a trough 46 00:03:02.310 --> 00:03:06.380 and then the wave starts wrapping around tighter and tighter 47 00:03:06.400 --> 00:03:10.470 and then it's almost like foam on the backside of the wave. The planetesimals get all 48 00:03:10.490 --> 00:03:14.540 stirred up and start colliding with one another and breaking into dust. 49 00:03:14.560 --> 00:03:18.570 We've learned so much about Beta Pictoris over the years 50 00:03:18.590 --> 00:03:22.590 but all the little pieces of evidence didn't seem to fit together before. 51 00:03:22.610 --> 00:03:26.670 This model has tied together in a nice, neat 52 00:03:26.690 --> 00:03:30.760 package, the story of Beta Pictoris and its planet. 53 00:03:30.780 --> 00:03:34.770 Erika Nesvold: In the future, we'll be able to use our SMACK models to 54 00:03:34.790 --> 00:03:38.820 study other debris disk systems and use our observations of 55 00:03:38.840 --> 00:03:42.870 those disks to predict the presence exoplanets that we 56 00:03:42.890 --> 00:03:46.910 otherwise wouldn't be able to detect. 57 00:03:46.930 --> 00:03:50.950 [Beeping] 58 00:03:50.970 --> 00:03:54.980 [Beeping] 59 00:03:55.000 --> 00:04:01.288 [Beeping]