14 a 17 de novembro | Brasília
CAsB - Clube de Astronomia de Brasília
Enviado por admin em 27/out/2013

Turbulencia de Plasmas Espaciais e o Dínamo Solar

Autor(es): George Eduardo Oliveira

Área do Trabalho: Astronomia Profissional / Acadêmica

Modalidade: Palestra

Apenas o resumo é em inglês, a palestra será em português.

Diverse and numerous nonlinear phenomena occurring in the universe at all times. In turn, these events and their predictions are limited in understanding because of its complexity, however, in recent years many advances are mainly due to computational numerical simulations, emphasize to these large-scale phenomena and describing its future prospects occurrence. In level astrophysical plasmas are studied in various fields, such as cosmic rays (galactic and extragalactic), interstellar and intergalactic media, accretion disks and jets in active galaxies nuclei (AGNs), pulsars, comets, etc. There are well-defined models for the description of turbulence in plasmas (with spectra, power laws and well-defined probability distribution functions of non-Gaussian), e.g equations of magneto-hydrodynamics (MHD), the direct simulation of these models in turbulent regimes analytical task is still computationally infeasible, due to the large number of spatial scales involved. Strictly speaking, the approaches are based on dynamical systems, with emphasis on the analysis of nonlinear plasma waves, such as Alfven waves and NLSD. The numerical solutions of the MHD equations in 3D space are visible in the intensity of the triad of the magnetic field at a given instant of time and in a box with periodic boundary conditions. Thus, we use the Pencil Code, a Code resistive MHD and compressible extensively tested and measured parameters required for the simulations of the solar dynamo. Observations obtained with the 4-satellite Cluster mission has revealed that the transfer of energy and momentum from the solar wind to the magnetosphere occurs by turbulent processes. This fact will allow us to determine how turbulence affects the plasma heating and transport processes of magnetic flux. Robust phase transitions to turbulence in plasmas via deterministic chaos have also been diagnosed in other models of temporal dynamics. The process of transition to spatiotemporal chaos can be used in an attempt to explain the broken symmetry and spatial coherence typical of turbulent systems. The analysis of observational data through computer simulations on large-scale clusters has confirmed the theoretical results, which suggest the existence of deterministic chaos behind the turbulent processes that occur in nature, in particular in the Sun-Earth connection. At most, we discuss some recent results from simulations of high energy astrophysics in clusters of galaxies, emphasizing the development of the cosmic plasma and frontiers of current problems in cosmology.

Referências sugeridas:

Brandenburg, A.; Subramanian, K. Astrophysical magnetic fields and nonlinear dynamo theory, Phys. Rep.417, 1 (2005).

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