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SUMMARY:Disc dynamos -- from galaxies to compact binaries - Oliver Gressel
  (Queen Mary)
DTSTART:20100208T160000Z
DTEND:20100208T170000Z
UID:TALK21867@talks.cam.ac.uk
CONTACT:Dr Geoffroy Lesur
DESCRIPTION:Accretion discs are a common phenomenon in astrophysics. They 
 can be found in objects spanning a huge range in magnitude. I will start m
 y talk presenting results from simulations of interstellar turbulence driv
 en by SNe. The occurring galaxy dynamo can successfully be described by me
 ans of kinematic mean-field theory.\n\nWith magnetic fields becoming dynam
 ically important\, we leave the realms of kinematic theory. Going to small
 er scales\, as relevant for protoplanetary discs\, I will show that dynami
 cally quenched mean-field models can reasonably well reproduce the "butter
 fly" diagram seen in stratified MRI simulations.\n\nFinally\, in compact b
 inary systems\, we find strongly magnetised discs. Here the MRI will not b
 e the only player but will be intertwined with the Parker instability. I c
 onfirm recent results by Johansen and Levin\, and show that differentially
  rotating discs can in fact retain their azimuthal flux\, counteracting ma
 gnetic buoyancy.
LOCATION:MR14\, DAMTP\, Pav. F
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