BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Contributed talk: Angular momentum transport in astrophysical dyna
 mos: simulations and experiments. - Christophe Gissinger (École Normale S
 upérieure)
DTSTART:20221201T163000Z
DTEND:20221201T170000Z
UID:TALK192149@talks.cam.ac.uk
DESCRIPTION:The radial transport of angular momentum is a central quantity
  in astrophysics\, as it is an essential ingredient in the dynamics of man
 y objects\, among which the best known are accretion discs or radiative st
 ars. In both cases\, the mechanism that generates the turbulence and the a
 mount of angular momentum transported outward remain to be clearly identif
 ied. Because it is deeply related to the generation of magnetic fields\, u
 nderstanding angular momentum transport is essential to dynamo theory.\n&n
 bsp\;\nIn this talk\, I will first describe a new laboratory experiment ai
 ming to reproduce a black hole or proto-star accretion disk in the laborat
 ory. In this experiment\, a Couette flow is driven by an electromagnetic f
 orce rather than by the rotation of the boundaries. When the electromagnet
 ic force applied to the liquid metal is large enough\, it provides a confi
 guration analogous to astrophysical disks\, characterized by a fully turbu
 lent flow that exhibits Keplerian rotation rates. The angular momentum is 
 then transported through a non-dissipative regime\, yielding predictions f
 or the accretion rates of astrophysical disks.\n&nbsp\;\nIn a second part\
 , I will describe global numerical simulations aiming to model a radiative
  stellar layer. For some parameters\, we report the existence of a subcrit
 ical transition to turbulence due to the generation of a dynamo magnetic&e
 nsp\;field\, very similar to the Tayler-Spruit model. This regime signific
 antly enhances turbulent transport in radiative zones\, leading to a drast
 ic spin-down of the inner part of the star.\n&nbsp\;\nBibliography:\nVerne
 t\, Fauve\, Gissinger\, Phys. Rev. Lett. (2022) Petitdemange\, Marcotte\, 
 Gissinger\, Science (in revision\, 2022)
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR