[Todos] Coloquios del Departamento de Física (jueves 29/9 y extra viernes 30/9)

[pdmitruk en df.uba.ar]

                 COLOQUIOS DEL DEPARTAMENTO DE FÍSICA FCEyN - UBA

                                 http://coloquios.df.uba.ar/

                                 Charla, café y galletitas
                   En el Aula Federman, 1er piso, Pabellón I,
                                   Ciudad Universitaria

                               Jueves 29 de septiembre, 14hs,

                                      SPACE WEATHER

                                        Ramon Lopez

                       Dept. of Physics, Univ. of Texas at Arlington

   As our technological civilization becomes more dependent of space
technology, we become more vulnerable to changes in the space environment
in which that technology functions.  These environmental changes are known
as ?space weather.?  In this talk I will discuss what drives space weather
and how it affects human activities both in space and on the Earth.  I will
also discuss recent efforts by the Center for Integrated Space Weather
Modeling to create physics-based numerical simulations of the magnetosphere
to be used in forecasting space weather.  


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                                               COLOQUIO EXTRA
                                     
                                      Viernes 30/9,  11hs, Aula Federman

                 Negative effective magnetic pressure instability in
turbulence simulations

                                                Axel Brandenburg

                                                NORDITA, Suecia

   We present the first numerical demonstration of the negative effective
   magnetic pressure instability in direct numerical simulations of
   stably-stratified, externally-forced, isothermal hydromagnetic
   turbulence. By the action of this instability, initially uniform
   horizontal magnetic field forms flux concentrations whose scale is
   large compared to the turbulent scale. We further show that the magnetic
   energy of these large-scale structures is only weakly dependent on
   the magnetic Reynolds number. Our results support earlier mean-field
   calculations and analytic work which identified this instability.
   Applications to the formation of active regions in the Sun are
   discussed.
    
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