1 00:00:00,010 --> 00:00:04,060 [Music] 2 00:00:04,080 --> 00:00:08,170 [Music] 3 00:00:08,190 --> 00:00:12,210 I'm Aki Roberge, 4 00:00:12,230 --> 00:00:16,250 an astronomer at NASA's Goddard Space Flight Center. I've been studying 5 00:00:16,270 --> 00:00:20,340 a young nearby planetary system around the bright star Beta Pictoris. 6 00:00:20,360 --> 00:00:24,350 Located 63 light-years away, and only about 7 00:00:24,370 --> 00:00:28,380 20 million years old, the star is surrounded by a vast disk of 8 00:00:28,400 --> 00:00:32,450 gas, dust and comet-like bodies that we view edgewise. 9 00:00:32,470 --> 00:00:36,470 We know of one planet in there too, it's a giant planet tracking along 10 00:00:36,490 --> 00:00:40,520 an orbit nearly as large as Saturn's. I'm part of a team 11 00:00:40,540 --> 00:00:44,570 studying Beta Pic's disk using the ALMA observatory in Chile. 12 00:00:44,590 --> 00:00:48,640 We've found something odd: a belt of carbon monoxide 13 00:00:48,660 --> 00:00:52,660 gas centered about three times farther from the star than Neptune's 14 00:00:52,680 --> 00:00:56,690 distance from the sun. The total amount of gas is about 15 00:00:56,710 --> 00:01:00,710 one-sixth the mass of all the water in Earth's oceans. What's 16 00:01:00,730 --> 00:01:04,720 interesting is that incoming ultraviolet light should break up the carbon 17 00:01:04,740 --> 00:01:08,760 monoxide molecules in little more than a century, on average. 18 00:01:08,780 --> 00:01:12,820 This means that the carbon monoxide must be resupplied by the breakup of icy 19 00:01:12,840 --> 00:01:16,890 comets. To produce the amount of gas we detect, we're looking at the 20 00:01:16,910 --> 00:01:21,030 equivalent of the total destruction of a large comet every 5 minutes. 21 00:01:21,050 --> 00:01:25,090 From our data, we can tell that much of the carbon monoxide 22 00:01:25,110 --> 00:01:29,110 is in one or two massive clumps, which was very surprising. 23 00:01:29,130 --> 00:01:33,170 Because we're viewing the disk edge-on, we can't be sure if its one or 24 00:01:33,190 --> 00:01:37,200 two. Regardless, the comets suppling the gas must also 25 00:01:37,220 --> 00:01:41,220 be concentrated into clumps. How could this happen? 26 00:01:41,240 --> 00:01:45,290 If there is one clump, we think we're seeing the aftermath of collision 27 00:01:45,310 --> 00:01:49,310 between two icy planets about the mass of Mars. 28 00:01:49,330 --> 00:01:53,350 Such a collision would have occurred about half a million years ago, releasing large 29 00:01:53,370 --> 00:01:57,370 quantities of gas and small, comet-like fragments. The second 30 00:01:57,390 --> 00:02:01,430 --and we think more likely--scenario is that the carbon monoxide 31 00:02:01,450 --> 00:02:05,460 exists in two clumps and is continually replenished by by collisions in 32 00:02:05,480 --> 00:02:09,510 huge comet swarms. We believe the comets are shepherded together 33 00:02:09,530 --> 00:02:13,570 by an as-yet-undetected second planet whose gravity confines 34 00:02:13,590 --> 00:02:17,610 the comets into a small region so the frequently collide. A planet 35 00:02:17,630 --> 00:02:21,650 with roughly Saturn's mass could do the job. Other observations 36 00:02:21,670 --> 00:02:25,720 hint that the brightest clump is moving in a way that makes the two clump 37 00:02:25,740 --> 00:02:29,770 scenario more likely. Further observations will track it in better detail 38 00:02:29,790 --> 00:02:33,820 and help us confirm this dramatic picture. 39 00:02:33,840 --> 00:02:37,880 [Music][Beeping] 40 00:02:37,900 --> 00:02:41,920 [Beeping] 41 00:02:41,940 --> 00:02:50,417 [Beeping]