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]