Analise espectral MHD em plasmas cilindricos de duas camadas. Aplicação a manchas solares

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

A cylindrical model is presented, in order to study the ideal magnetohydrodynamic (MHD) spectrum. We modeled a two-layered cylindrical plasma, where two regions are defined, an internal and an external one, with different aspects each other. A diffuse longitudinal current is present in the internal region, so, twisted magnetic fields with a small Bq / Bz ratio are assumed in both region. A numerical code as developed for this model, in order to get oscillations modes, originated from the plasma disturbances, via MHD theory. The various spectra, solutions of this code, are studied carefully. Due the double layer, it is verified combined modes (slow, Alfvén or fast ones) in the spectra. These combined modes are separated by continua regions. Sturmian and anti-Sturmian behaviour of the functions are proved numerically in a definite way. Connected with these discontinuities, surface waves are obtained. We suggest a large application of this model in the study of solar and astrophysical objects oscillations, as well in the thermonuclear fusion analysis. In particular, we apply the model to sunspots. It is noted that estimated periods obtained by our model are comparable to the periods obtained from observational data, mainly umbral oscillations and the running penumbral waves

ASSUNTO(S)

manchas solares ondas magnetoidrodinamicas

ACESSO AO ARTIGO

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