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SUMMARY:Probing convection and magnetic dynamos deep within stars - Juri T
 oomre (ILA and Department of Astrophysical and Planetary Sciences\, Univer
 sity of Colorado Boulder)
DTSTART:20160318T143000Z
DTEND:20160318T153000Z
UID:TALK65037@talks.cam.ac.uk
CONTACT:Jean Teyssandier
DESCRIPTION:The rich magnetism displayed by many stars\, including our sun
 \, must have their origin in dynamo\naction proceeding within their convec
 tion zones involving highly turbulent flows influenced by\nrotation and st
 ratification. The striking advances in seismic probing of stars is providi
 ng guidance\nabout rotation states\, and possibly of magnetism\, deep with
 in a range of stars. This is\ncomplemented by supercomputing advances that
  now permit 3-D global simulations\, such as with\nour anelastic spherical
  harmonic (ASH) code\, of solar and stellar convection to study the nature
  of\nmagnetic dynamo action and differential rotation that can be achieved
  by complex flows involving\na hierarchy of scales and patterns. In rotati
 ng sun-like stars with convective envelopes\, we have\nfound using ASH mod
 eling that the resulting magnetic fields can exhibit remarkable large-scal
 e\nstructure involving wreaths of strong magnetism amidst the turbulent co
 nvection. These wreaths\ncan involve temporal flips and even quite regular
  cycles. In one prominent case that cycling with\nreversals was interrupte
 d by a more quiescent interval\, afterwhich the cycling resumed\, not unli
 ke a\nMaunder Minimum. In more massive B-type rotating stars that have con
 vective cores and\nradiative envelopes\, we find with our ASH studies that
  core dynamo action can yield super-\nequipartition magnetic fields withme
 ga-gauss strengths. These intense fields may have implications\nin later s
 tages of evolution\, whether in the cores of red giants or in the survivor
 s of supernova\nexplosions. These overlaps in observations and computation
 al theory make for a period of major\nadventures in stellar astrophysics.
LOCATION:MR2\,  Centre for Mathematical Sciences\, Wilberforce Road\, Camb
 ridge
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