1 00:00:00,790 --> 00:00:07,270 [Music] 2 00:00:13,129 --> 00:00:10,190 my name is Scott Soriano I'm a grad 3 00:00:15,169 --> 00:00:13,139 student at at UVA in the Astronomy 4 00:00:17,090 --> 00:00:15,179 Department I just want to thank the 5 00:00:18,320 --> 00:00:17,100 organizers quickly for having a 6 00:00:20,450 --> 00:00:18,330 conference in Charlottesville it's 7 00:00:22,279 --> 00:00:20,460 awesome it's so convenient okay 8 00:00:24,890 --> 00:00:22,289 I also want to thank our previous 9 00:00:26,599 --> 00:00:24,900 speaker Ryan for giving a bunch of 10 00:00:28,460 --> 00:00:26,609 background for for what my talk is gonna 11 00:00:31,400 --> 00:00:28,470 be about I'll just move to the next 12 00:00:32,810 --> 00:00:31,410 slide - awesome okay all right so you 13 00:00:36,350 --> 00:00:32,820 guys already you know all this I'm done 14 00:00:39,380 --> 00:00:36,360 I'll go now right so on the Left we have 15 00:00:45,680 --> 00:00:39,390 HL tau protoplanetary disc on the right 16 00:00:46,970 --> 00:00:45,690 - W Hydra and so again again more 17 00:00:49,430 --> 00:00:46,980 background because you just learned a 18 00:00:52,549 --> 00:00:49,440 bunch of this stuff but these are almond 19 00:00:54,020 --> 00:00:52,559 images around one millimeter continuum 20 00:00:55,700 --> 00:00:54,030 images so what you're actually what 21 00:00:57,470 --> 00:00:55,710 you're seeing is the emission of dust 22 00:00:57,889 --> 00:00:57,480 grains that are about that same size one 23 00:01:00,260 --> 00:00:57,899 milliliter 24 00:01:03,139 --> 00:01:00,270 and TW Hydra on the right is actually 25 00:01:07,010 --> 00:01:03,149 the closest gaseous protoplanetary disc 26 00:01:10,490 --> 00:01:07,020 to the earth so again just all the stuff 27 00:01:12,080 --> 00:01:10,500 but you can get you can get really 28 00:01:13,880 --> 00:01:12,090 resolve really small scales in these 29 00:01:16,760 --> 00:01:13,890 things right so in the top right you can 30 00:01:20,990 --> 00:01:16,770 see you're resolving the the disk 31 00:01:22,310 --> 00:01:21,000 structure down to about one au one thing 32 00:01:24,590 --> 00:01:22,320 that was just briefly mentioned however 33 00:01:27,499 --> 00:01:24,600 not in the previous talk was the fact 34 00:01:30,830 --> 00:01:27,509 that photo planetary discs launch 35 00:01:33,920 --> 00:01:30,840 bipolar outflows and so on the right so 36 00:01:36,140 --> 00:01:33,930 the left again HL tau the right is also 37 00:01:38,240 --> 00:01:36,150 an image of HL tau so they're in the 38 00:01:41,330 --> 00:01:38,250 bottom right of this picture but what 39 00:01:44,840 --> 00:01:41,340 you're seeing here is on a wide angle 40 00:01:46,580 --> 00:01:44,850 wind being launched close to the disc so 41 00:01:47,870 --> 00:01:46,590 it's like this and you see there's a 42 00:01:50,510 --> 00:01:47,880 wind being launched like this and then 43 00:01:53,080 --> 00:01:50,520 you have a very well collimated jet 44 00:01:55,160 --> 00:01:53,090 that's being launched and extends of 45 00:01:58,219 --> 00:01:55,170 quite a long distance actually it's 46 00:02:02,569 --> 00:01:58,229 interacting with the Jets from from 47 00:02:04,639 --> 00:02:02,579 other proto stars in the region and so 48 00:02:06,679 --> 00:02:04,649 just another example of this this is a 49 00:02:10,490 --> 00:02:06,689 pretty famous one this is HH 30 this is 50 00:02:12,110 --> 00:02:10,500 a Hubble image and so on the left 51 00:02:13,940 --> 00:02:12,120 against the disc diameter here is about 52 00:02:15,740 --> 00:02:13,950 200 au and 53 00:02:20,420 --> 00:02:15,750 you can see a very very well collimated 54 00:02:22,250 --> 00:02:20,430 jet being launched up right and then on 55 00:02:24,800 --> 00:02:22,260 the right so this is a over a six year 56 00:02:26,240 --> 00:02:24,810 period through just three images taken 57 00:02:27,500 --> 00:02:26,250 over six year period so you can sort of 58 00:02:30,080 --> 00:02:27,510 see the evolution of the jet you can 59 00:02:32,059 --> 00:02:30,090 even see specific knots in the jet 60 00:02:36,100 --> 00:02:32,069 moving outward as they're launched from 61 00:02:39,949 --> 00:02:36,110 the disk surface so even more recently 62 00:02:42,770 --> 00:02:39,959 another Alma observation one of the best 63 00:02:45,789 --> 00:02:42,780 examples of a wide-angle disc wind being 64 00:02:48,920 --> 00:02:45,799 launched from a protoplanetary disc so 65 00:02:50,300 --> 00:02:48,930 what's actually going on here is it's a 66 00:02:52,250 --> 00:02:50,310 magnetic phenomenon that's that's 67 00:02:58,180 --> 00:02:52,260 launching this extended disc wind up 68 00:03:02,509 --> 00:03:00,800 right what it's called it's called an MH 69 00:03:05,150 --> 00:03:02,519 d disc when MH d is magneto 70 00:03:08,390 --> 00:03:05,160 hydrodynamics the study of the dynamics 71 00:03:10,850 --> 00:03:08,400 of magnetized fluids and so this is a 72 00:03:15,710 --> 00:03:10,860 really good example of a protoplanetary 73 00:03:17,630 --> 00:03:15,720 disc launching a wide-angle wind through 74 00:03:19,670 --> 00:03:17,640 through this magnetic phenomenon that 75 00:03:23,990 --> 00:03:19,680 I'll discuss right now I'll give you 76 00:03:27,349 --> 00:03:24,000 just a quick overview of how the MHD 77 00:03:28,759 --> 00:03:27,359 disc wind disc winds are launched so 78 00:03:31,370 --> 00:03:28,769 here we have it just an edge-on view of 79 00:03:34,000 --> 00:03:31,380 a disc right here is the mid plane of 80 00:03:37,340 --> 00:03:34,010 the disc these solid black lines are 81 00:03:40,400 --> 00:03:37,350 right here they are magnetic field lines 82 00:03:42,080 --> 00:03:40,410 threading the disc vertically and so the 83 00:03:44,449 --> 00:03:42,090 simple concept is just if you have a 84 00:03:46,610 --> 00:03:44,459 magnetic field line threading the disc 85 00:03:49,000 --> 00:03:46,620 it's pointing outward away from the axis 86 00:03:52,309 --> 00:03:49,010 of rotation you can actually launch 87 00:03:53,960 --> 00:03:52,319 material Magneto's are centrifugal II 88 00:03:56,150 --> 00:03:53,970 right you just do force do a force 89 00:03:59,420 --> 00:03:56,160 balance along this line since it's 90 00:04:02,080 --> 00:03:59,430 rotating you actually you just if you've 91 00:04:06,129 --> 00:04:02,090 lift any parcel of gas up off the disc 92 00:04:10,520 --> 00:04:06,139 it can be launched along this field line 93 00:04:12,680 --> 00:04:10,530 and so the idea in ideal MHD so this the 94 00:04:15,349 --> 00:04:12,690 simplest set of equations you can write 95 00:04:19,270 --> 00:04:15,359 down to describe magnetized fluids the 96 00:04:21,500 --> 00:04:19,280 general idea is that the matter then the 97 00:04:23,029 --> 00:04:21,510 matter is completely tied to the 98 00:04:25,640 --> 00:04:23,039 magnetic field so they sort of move 99 00:04:27,409 --> 00:04:25,650 together at the same time and so if you 100 00:04:29,149 --> 00:04:27,419 relax that assumption 101 00:04:30,649 --> 00:04:29,159 equations get a little more complicated 102 00:04:33,140 --> 00:04:30,659 but what happens is you can have the 103 00:04:35,390 --> 00:04:33,150 matter flowing diffusing through the 104 00:04:37,129 --> 00:04:35,400 magnetic fields and so what you have is 105 00:04:39,379 --> 00:04:37,139 you can have a matter creating through 106 00:04:41,089 --> 00:04:39,389 the disk some fraction of the masses are 107 00:04:43,189 --> 00:04:41,099 created onto the central star some 108 00:04:47,659 --> 00:04:43,199 fraction of the mass is launched into 109 00:04:49,040 --> 00:04:47,669 into the disk wind and so how the disk 110 00:04:50,779 --> 00:04:49,050 win actually works like how much mass 111 00:04:53,689 --> 00:04:50,789 you actually lose in the wind compared 112 00:04:56,119 --> 00:04:53,699 to how much you accrete where it's 113 00:04:58,159 --> 00:04:56,129 launched from all depends on disk micro 114 00:05:02,209 --> 00:04:58,169 physics of specifically like the disk 115 00:05:05,149 --> 00:05:02,219 chemistry so it has to do a lot with the 116 00:05:07,820 --> 00:05:05,159 ionization fraction of the disk right so 117 00:05:09,379 --> 00:05:07,830 the low the more ionized the the matter 118 00:05:11,510 --> 00:05:09,389 is the more well couple it is to the 119 00:05:13,879 --> 00:05:11,520 magnetic field and so in the mid plane 120 00:05:15,860 --> 00:05:13,889 of the disk it's actually quite cold 121 00:05:17,990 --> 00:05:15,870 ionization fraction is very low you're 122 00:05:21,950 --> 00:05:18,000 not well coupled to them at a magnetic 123 00:05:24,589 --> 00:05:21,960 field and so as you move up towards the 124 00:05:27,860 --> 00:05:24,599 surface of the disk the stellar light 125 00:05:29,480 --> 00:05:27,870 cellar UV and x-ray photons illuminate 126 00:05:32,059 --> 00:05:29,490 can actually hit the surface of the disk 127 00:05:34,370 --> 00:05:32,069 heating it up therefore increasing your 128 00:05:36,439 --> 00:05:34,380 ionization fraction and that's actually 129 00:05:40,339 --> 00:05:36,449 where the the base of the wind is going 130 00:05:43,010 --> 00:05:40,349 to be launched and then you also have 131 00:05:45,260 --> 00:05:43,020 the disk will be truncated due to the 132 00:05:47,779 --> 00:05:45,270 dust sublimation temperature and also 133 00:05:51,230 --> 00:05:47,789 you might have some gas inside of the 134 00:05:52,249 --> 00:05:51,240 the dust dust disk and that's going to 135 00:05:54,830 --> 00:05:52,259 be truncated by the stellar 136 00:05:59,119 --> 00:05:54,840 magnetosphere so this is going to be 137 00:06:00,860 --> 00:05:59,129 around point 1 au and then maybe the the 138 00:06:05,450 --> 00:06:00,870 gas disc can extend even further to say 139 00:06:07,790 --> 00:06:05,460 0.01 au and so why our disk winds 140 00:06:14,390 --> 00:06:07,800 important well one thing is they they 141 00:06:16,999 --> 00:06:14,400 drive the angular momentum they sorry 142 00:06:19,790 --> 00:06:17,009 they they drive angular momentum 143 00:06:21,649 --> 00:06:19,800 transport in the disk so and in the 90s 144 00:06:24,619 --> 00:06:21,659 it was thought that I was more thought 145 00:06:26,869 --> 00:06:24,629 that um you sort of you can exchange 146 00:06:28,790 --> 00:06:26,879 angular momentum through the disk via 147 00:06:29,930 --> 00:06:28,800 something called the MRI which I want to 148 00:06:33,559 --> 00:06:29,940 talk about but it's just some sort of 149 00:06:35,420 --> 00:06:33,569 magnetized turbulence and so recently if 150 00:06:36,589 --> 00:06:35,430 you actually do some of the complicated 151 00:06:37,939 --> 00:06:36,599 chemistry stuff that I was just talking 152 00:06:40,700 --> 00:06:37,949 about well I didn't talk about the 153 00:06:42,590 --> 00:06:40,710 calculated stuff but if you do some more 154 00:06:45,230 --> 00:06:42,600 tailed models you actually find that the 155 00:06:47,660 --> 00:06:45,240 disc wind actually controls the angular 156 00:06:50,080 --> 00:06:47,670 momentum loss in the disc it controls 157 00:06:52,040 --> 00:06:50,090 the global evolution of the disc and 158 00:06:55,370 --> 00:06:52,050 specifically it controls the global 159 00:06:57,620 --> 00:06:55,380 evolution of the disc on the scales of 160 00:07:00,590 --> 00:06:57,630 the disc where planets are forming so on 161 00:07:02,480 --> 00:07:00,600 the right we can see so this is from 162 00:07:04,220 --> 00:07:02,490 exoplanets or gets pretty cool website I 163 00:07:05,420 --> 00:07:04,230 should check it out but so these are 164 00:07:07,850 --> 00:07:05,430 these are all the exoplanets we have 165 00:07:10,790 --> 00:07:07,860 observed as of last year July of last 166 00:07:13,460 --> 00:07:10,800 year and as you can see down here in the 167 00:07:15,740 --> 00:07:13,470 blue this is where we find most most 168 00:07:17,840 --> 00:07:15,750 exoplanets at least the ones we find 169 00:07:19,850 --> 00:07:17,850 with Kepler most known exoplanets our 170 00:07:22,550 --> 00:07:19,860 good ally in this region right so this 171 00:07:23,840 --> 00:07:22,560 is 0.1 au a tenth of the distance 172 00:07:25,460 --> 00:07:23,850 between the Earth and the Sun so closer 173 00:07:27,590 --> 00:07:25,470 to their host stars and the earth is and 174 00:07:29,210 --> 00:07:27,600 also they're going to be around point l1 175 00:07:31,460 --> 00:07:29,220 Jupiter masses which is like a few Earth 176 00:07:33,980 --> 00:07:31,470 masses so we call them super earth 177 00:07:37,430 --> 00:07:33,990 sometimes mini Neptune's if they have 178 00:07:40,100 --> 00:07:37,440 larger gas envelopes and so the disk 179 00:07:41,840 --> 00:07:40,110 winds are are very important in driving 180 00:07:44,000 --> 00:07:41,850 the global disk evolution right in the 181 00:07:46,220 --> 00:07:44,010 regions where planets are forming and so 182 00:07:49,850 --> 00:07:46,230 it can have a large impact on on what 183 00:07:51,980 --> 00:07:49,860 types of planets can form there and so 184 00:07:53,630 --> 00:07:51,990 the question we wanted to ask was can 185 00:07:55,340 --> 00:07:53,640 disk winds create the radial sub 186 00:07:58,100 --> 00:07:55,350 structures that we we are now observing 187 00:07:59,660 --> 00:07:58,110 in disks can they can can they be 188 00:08:03,470 --> 00:07:59,670 responsible for creating rings and gaps 189 00:08:07,430 --> 00:08:03,480 and protoplanetary disks so I have to 190 00:08:08,870 --> 00:08:07,440 mention that there are other mechanisms 191 00:08:13,510 --> 00:08:08,880 performing them specifically I'll just 192 00:08:17,060 --> 00:08:13,520 mention planets because it's the most 193 00:08:18,740 --> 00:08:17,070 wealth well developed idea that you can 194 00:08:22,220 --> 00:08:18,750 have a large planet sort of carving out 195 00:08:24,830 --> 00:08:22,230 its its own orbit and creating a gap but 196 00:08:27,770 --> 00:08:24,840 there there are a lot of really small 197 00:08:28,820 --> 00:08:27,780 rings too so there might be room for 198 00:08:31,370 --> 00:08:28,830 other things there are some other 199 00:08:35,450 --> 00:08:31,380 mechanisms that I won't that I'll just 200 00:08:38,510 --> 00:08:35,460 move on from though so um right so the 201 00:08:40,550 --> 00:08:38,520 question we want to ask is can MHD disk 202 00:08:43,040 --> 00:08:40,560 winds be responsible chemin it feels be 203 00:08:45,470 --> 00:08:43,050 responsible for creating substructure 204 00:08:47,540 --> 00:08:45,480 and disks and so how do we do how do we 205 00:08:52,250 --> 00:08:47,550 set up this problem well what we do we 206 00:08:53,820 --> 00:08:52,260 do MHD simulations in grid codes so what 207 00:08:57,480 --> 00:08:53,830 we do is we set a 208 00:08:58,800 --> 00:08:57,490 a static grid we define the mass tent 209 00:09:00,840 --> 00:08:58,810 you define all these parameters those 210 00:09:02,790 --> 00:09:00,850 are the MHD equations in the top right 211 00:09:04,920 --> 00:09:02,800 you define all those parameters in each 212 00:09:07,440 --> 00:09:04,930 grid cell in us in these static cells 213 00:09:10,980 --> 00:09:07,450 and as a function of time you evolve 214 00:09:13,680 --> 00:09:10,990 these equations and you can the the 215 00:09:15,930 --> 00:09:13,690 density the magnetic field are affected 216 00:09:19,620 --> 00:09:15,940 through the cells and so you have an 217 00:09:22,920 --> 00:09:19,630 idea of sort of the evolution of the 218 00:09:25,980 --> 00:09:22,930 problem that you're setting up so the 219 00:09:27,870 --> 00:09:25,990 code we use is the Zeus code now on the 220 00:09:29,550 --> 00:09:27,880 bottom right is just an example an 221 00:09:32,580 --> 00:09:29,560 initial setup of of one of our 222 00:09:35,040 --> 00:09:32,590 simulation so again an edge on disk just 223 00:09:36,630 --> 00:09:35,050 one hemisphere but you can see that the 224 00:09:39,210 --> 00:09:36,640 magenta lines are the other magnetic 225 00:09:40,830 --> 00:09:39,220 field that are vertically threading the 226 00:09:46,680 --> 00:09:40,840 disk which is going to allow for the 227 00:09:48,870 --> 00:09:46,690 launching of the winds right and we we 228 00:09:51,600 --> 00:09:48,880 do include one non-ideal effect so that 229 00:09:54,180 --> 00:09:51,610 is saying just that the magnetic field 230 00:09:58,620 --> 00:09:54,190 can that the matter can diffuse through 231 00:10:00,240 --> 00:09:58,630 the magnetic field right so I'm just 232 00:10:01,350 --> 00:10:00,250 gonna hopefully these movies work I'm 233 00:10:03,240 --> 00:10:01,360 just going to show it go right to the 234 00:10:12,410 --> 00:10:03,250 results of the one of the simulations 235 00:10:20,990 --> 00:10:18,949 oh um that's funny it's working out here 236 00:10:23,660 --> 00:10:21,000 I was had to click to the side of the 237 00:10:29,000 --> 00:10:23,670 button on the screen you guys think I'm 238 00:10:31,280 --> 00:10:29,010 just okay I'll try okay so the results 239 00:10:33,050 --> 00:10:31,290 of the simulation we have on the Left we 240 00:10:34,250 --> 00:10:33,060 have the surface density again the the 241 00:10:37,220 --> 00:10:34,260 white lines are magnetic field lines 242 00:10:38,000 --> 00:10:37,230 gray unit vectors are the velocity 243 00:10:39,710 --> 00:10:38,010 components 244 00:10:42,139 --> 00:10:39,720 the ploy Daleville ah sities of the 245 00:10:45,769 --> 00:10:42,149 velocity in the plane of the screen on 246 00:10:48,259 --> 00:10:45,779 the right is a DMD theta which is just 247 00:10:51,470 --> 00:10:48,269 like a sort of a mass flux it's just Rho 248 00:10:52,879 --> 00:10:51,480 times V plus a geometric term so just 249 00:10:54,949 --> 00:10:52,889 think of it as mass flux so if it's red 250 00:10:58,310 --> 00:10:54,959 it's moving outward blue it's moving 251 00:11:04,490 --> 00:10:58,320 inward and on the right is um a face on 252 00:11:05,990 --> 00:11:04,500 view of the surface density again it's 253 00:11:07,579 --> 00:11:06,000 only a 2d simulation so we're assuming 254 00:11:09,620 --> 00:11:07,589 it's actually symmetric here to make 255 00:11:11,900 --> 00:11:09,630 this the third plot but as you can see 256 00:11:15,009 --> 00:11:11,910 materials being is leaving the 257 00:11:17,449 --> 00:11:15,019 simulation domain through the wind 258 00:11:19,100 --> 00:11:17,459 materials in blue as you see in the disk 259 00:11:21,110 --> 00:11:19,110 is being accreted through the disk mid 260 00:11:22,790 --> 00:11:21,120 plane and then on the right you can see 261 00:11:26,660 --> 00:11:22,800 the formation of these these radial 262 00:11:29,060 --> 00:11:26,670 structures the Rings and gas and so I 263 00:11:31,280 --> 00:11:29,070 have a little a little made a little 264 00:11:32,990 --> 00:11:31,290 cartoon to describe the actual mechanism 265 00:11:35,750 --> 00:11:33,000 as to how you are really forming these 266 00:11:37,819 --> 00:11:35,760 rings and gaps in these simulations so 267 00:11:40,340 --> 00:11:37,829 the the idea is that you have you have 268 00:11:42,230 --> 00:11:40,350 matter creating through the disk so you 269 00:11:44,210 --> 00:11:42,240 have some mass accretion rate through 270 00:11:48,019 --> 00:11:44,220 the disk if some mess out flow rate in 271 00:11:50,900 --> 00:11:48,029 the wind I'm so in any one section of 272 00:11:52,550 --> 00:11:50,910 the disk the the magnetic flux in that 273 00:11:55,850 --> 00:11:52,560 section is just proportional to the 274 00:11:59,930 --> 00:11:55,860 vertical magnetic fields there so say 275 00:12:02,059 --> 00:11:59,940 for example you have a magnetic flux 276 00:12:04,130 --> 00:12:02,069 concentration at any one part of the 277 00:12:06,079 --> 00:12:04,140 disk what you're going to do is you can 278 00:12:08,960 --> 00:12:06,089 drive faster accretion through that the 279 00:12:10,970 --> 00:12:08,970 magnetic field applies a torque on the 280 00:12:13,370 --> 00:12:10,980 disk and so you can drive accretion 281 00:12:15,710 --> 00:12:13,380 through that region more efficiently 282 00:12:18,470 --> 00:12:15,720 than before and so you just have a 283 00:12:20,569 --> 00:12:18,480 buildup of mass interior to the gap that 284 00:12:24,110 --> 00:12:20,579 you just created where you'll have a 285 00:12:25,579 --> 00:12:24,120 ring right here and so what you see in 286 00:12:26,269 --> 00:12:25,589 this process is you see this anti 287 00:12:28,069 --> 00:12:26,279 correlation 288 00:12:30,639 --> 00:12:28,079 the surface density of this top plot and 289 00:12:33,439 --> 00:12:30,649 the vertical magnetic field strength 290 00:12:35,269 --> 00:12:33,449 right so in the in the Rings you have 291 00:12:37,550 --> 00:12:35,279 have a lot of mass and you don't have a 292 00:12:39,800 --> 00:12:37,560 lot of magnetic flux again the non-ideal 293 00:12:41,869 --> 00:12:39,810 effects are important here where you can 294 00:12:46,819 --> 00:12:41,879 have matter diffuse through the magnetic 295 00:12:49,340 --> 00:12:46,829 field and then so what you the criterion 296 00:12:52,429 --> 00:12:49,350 you need to form these the Rings and 297 00:12:54,650 --> 00:12:52,439 gaps in these simulations is just that 298 00:12:56,239 --> 00:12:54,660 you need the angular momentum removal 299 00:13:00,439 --> 00:12:56,249 rate which is provided by the magnetic 300 00:13:02,509 --> 00:13:00,449 fields in the wind to to vary as a 301 00:13:04,009 --> 00:13:02,519 function of radius so at any point you 302 00:13:06,949 --> 00:13:04,019 have an over dense you have more 303 00:13:09,439 --> 00:13:06,959 magnetic flux in some region for example 304 00:13:11,600 --> 00:13:09,449 that the mass accretion rate is going to 305 00:13:15,619 --> 00:13:11,610 be proportional to the vertical magnetic 306 00:13:17,509 --> 00:13:15,629 field B Phi or B Z as I had before you 307 00:13:20,600 --> 00:13:17,519 can efficiently clear that region out of 308 00:13:25,519 --> 00:13:20,610 mass and a Cree material just inside of 309 00:13:29,030 --> 00:13:25,529 that gap so another another mechanism 310 00:13:30,410 --> 00:13:29,040 for forming rings in in these 311 00:13:32,540 --> 00:13:30,420 simulations is that you have these 312 00:13:34,490 --> 00:13:32,550 things that we call surface accretion 313 00:13:37,790 --> 00:13:34,500 streams or avalanches as they might have 314 00:13:40,069 --> 00:13:37,800 been called previously the general idea 315 00:13:42,530 --> 00:13:40,079 here is that you have if you have any 316 00:13:44,059 --> 00:13:42,540 pinch on the surface of the pinch in the 317 00:13:45,199 --> 00:13:44,069 magnetic field on the surface of the 318 00:13:48,619 --> 00:13:45,209 disc as you can see our in the outer 319 00:13:51,319 --> 00:13:48,629 region you can drive mass accretion in 320 00:13:53,509 --> 00:13:51,329 this region very very quickly is because 321 00:13:55,639 --> 00:13:53,519 the pinch means that you have a very 322 00:13:57,290 --> 00:13:55,649 strong magnetic field there and so 323 00:13:59,030 --> 00:13:57,300 what's happening is you you're piling 324 00:14:05,059 --> 00:13:59,040 massive very quick through this stream 325 00:14:10,699 --> 00:14:05,069 on to a specific radius 0.5 au here and 326 00:14:12,829 --> 00:14:10,709 so I'll quickly show this happening in 327 00:14:18,860 --> 00:14:12,839 another movie again the same parameters 328 00:14:20,809 --> 00:14:18,870 as the previous movie and so you can see 329 00:14:23,119 --> 00:14:20,819 right here is where the stream is you 330 00:14:26,540 --> 00:14:23,129 have a large mass flux through this 331 00:14:37,930 --> 00:14:26,550 region piling up mass here and that can 332 00:14:44,080 --> 00:14:40,060 so that's a second mechanism for 333 00:14:46,510 --> 00:14:44,090 possibly forming rings and 334 00:14:51,700 --> 00:14:46,520 protoplanetary disks so I only have I 335 00:14:54,310 --> 00:14:51,710 have five seconds left yeah so just to 336 00:14:57,270 --> 00:14:54,320 bring it back to relate it back to the 337 00:14:59,650 --> 00:14:57,280 conference why is this important well 338 00:15:01,960 --> 00:14:59,660 the Rings are going to be dust traps 339 00:15:03,780 --> 00:15:01,970 that's where you could possibly so as 340 00:15:06,700 --> 00:15:03,790 you have dust drifting through the disk 341 00:15:08,290 --> 00:15:06,710 the the high surface density regions are 342 00:15:10,600 --> 00:15:08,300 we also have a pressure maximum and 343 00:15:13,090 --> 00:15:10,610 those pressure maximums can trap 344 00:15:15,820 --> 00:15:13,100 drifting dust grains and possibly that's 345 00:15:19,210 --> 00:15:15,830 where you can grow grow grains and form 346 00:15:23,860 --> 00:15:19,220 planets I'm out of time so I'm just 347 00:15:25,090 --> 00:15:23,870 going to leave that up there so okay 348 00:15:40,140 --> 00:15:25,100 thank you 349 00:15:46,570 --> 00:15:44,260 okay so um quick question on this with 350 00:15:49,990 --> 00:15:46,580 the size scales that you are looking at 351 00:15:52,180 --> 00:15:50,000 so it looked like these simulations that 352 00:15:55,240 --> 00:15:52,190 you're doing are on the the first au 353 00:15:57,190 --> 00:15:55,250 which from the Andrews paper we do see 354 00:15:59,200 --> 00:15:57,200 these sorts of rings on au scales right 355 00:16:01,480 --> 00:15:59,210 but there's also all of the outer rings 356 00:16:03,340 --> 00:16:01,490 so if you looked at how these it look 357 00:16:05,740 --> 00:16:03,350 like in the simulations that they're 358 00:16:07,150 --> 00:16:05,750 kind of propagating outwards how do you 359 00:16:09,070 --> 00:16:07,160 think this would affect the outer disk 360 00:16:11,380 --> 00:16:09,080 and would it propagate all the way out 361 00:16:14,110 --> 00:16:11,390 or are you mainly using this to describe 362 00:16:15,610 --> 00:16:14,120 like those those inner rings that they 363 00:16:18,070 --> 00:16:15,620 see in the Andrews paper right good 364 00:16:19,570 --> 00:16:18,080 question yeah so we initially you pick 365 00:16:21,460 --> 00:16:19,580 these size scales because it was the 366 00:16:23,320 --> 00:16:21,470 planet forming regions where we see a 367 00:16:27,130 --> 00:16:23,330 lot of Kepler planets 368 00:16:28,960 --> 00:16:27,140 and also the the one non ideal MHD 369 00:16:31,450 --> 00:16:28,970 effect is that that's actually where it 370 00:16:33,280 --> 00:16:31,460 is most important in less than one at 371 00:16:34,960 --> 00:16:33,290 you for example and so there are more 372 00:16:36,970 --> 00:16:34,970 effects when you've taken account as we 373 00:16:39,280 --> 00:16:36,980 do the same simulation in the outer 374 00:16:43,780 --> 00:16:39,290 regions of the disk which I was gonna 375 00:16:45,430 --> 00:16:43,790 show thanks for asking but so this is 376 00:16:47,920 --> 00:16:45,440 just included a little bit further out 377 00:16:49,390 --> 00:16:47,930 right so the small scales that I was 378 00:16:52,450 --> 00:16:49,400 showing aren't really that observable 379 00:16:54,570 --> 00:16:52,460 right that was like up to 0.02 au was 380 00:16:56,680 --> 00:16:54,580 was the inner boundary of our simulation 381 00:16:59,680 --> 00:16:56,690 but you can have the same mechanism 382 00:17:01,180 --> 00:16:59,690 happen further out this is some new work 383 00:17:04,450 --> 00:17:01,190 that we're working on with it with a 384 00:17:05,860 --> 00:17:04,460 different non ideal MHD effect and be 385 00:17:08,380 --> 00:17:05,870 polar fusion which will be more 386 00:17:09,330 --> 00:17:08,390 important around 10 au and so that's 387 00:17:18,289 --> 00:17:09,340 something we're looking into