Kress, Monika
<p>Jun 3, 2010 10:28 AM
 
MONIKA KRESS,  Assoc Prof  SJ State  (just got tenure)
 
Conservation of angul momentum  in accretion disks.
 
disks  have  temp > 500 K  at  1 AU
(so how do u get  planet accretion).
 
the compos of the interstellar material is v impt  for the compos of the planets.
 
Can  readily see young stellar disks by Hubble  in infrared.
 
how many stars have disks...  if star is < 1 MY old  then 80% have disks.
 
must have boulders to make planets.
 
Temperat (R)  =  2000 degr K   (R /  Rstar) -p
 
R  star is the stellar radius
 
p depends of the grain size of interstel med.
 
takes  1 M  years to lose angular momentum  but it does disappear  via
at least 4 mechs  (that is why accretion disks are < 1 MY old... if ur gonna
form planets u need to do it right away before  disk  loses momenturm.
 
Rayleigh-Taylor  instability.
 
magnetorotational instability
 
Chemistry of Disks
 
PAHs  polycyclic aromatic hydrocarbons  HCs.  eg  pyrene is  a PAH  see wiki.
 
carbonac chondrites in meterorites  have lots of carbon.
 
PAhs  are v  strong....  realy strong  pi-bonds.
 
in  ISmedium  1% is carbon  and 10 to 20% of that carbon is in  PAHs.
 
may be v important for OUR carbon on earth... CO  would've evaporated...  too hot in habit zone.
 
DISKS  cook up PAHs  they make them.
 
PAHs  are rapidly destoryed by higher temps.
 
?? how to make planet EArth out of  boulders....  why shud the boulders stick together
rather than just hanging out.
 
disk  dynamics...  shear is present...  depends on eccentricity and inclination.
 
see Sean Raymond  2010  paper.
 
planetsiimals  are  1 km
embryos are  1000 km
planets  are  104 km.
 
disks r a process
 
Q  hot jupiters
A   they are  formed  way out and then migrate in..
 
 
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