Busca avançada
Ano de início
Entree
Conteúdo relacionado
(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

ON THE ROLE OF TACHOCLINES IN SOLAR AND STELLAR DYNAMOS

Texto completo
Autor(es):
Guerrero, G. [1] ; Smolarkiewicz, P. K. [2] ; de Gouveia Dal Pino, E. M. [3] ; Kosovichev, A. G. [4] ; Mansour, N. N. [5]
Número total de Autores: 5
Afiliação do(s) autor(es):
[1] Univ Fed Minas Gerais, Dept Phys, Ave Antonio Carlos 6627, BR-31270901 Belo Horizonte, MG - Brazil
[2] European Ctr Medium Range Weather Forecasts, Shinfield Pk, Reading RG2 9AX, Berks - England
[3] Univ Sao Paulo, IAG, Dept Astron, Rua Mato 1226, BR-05508090 Sao Paulo, SP - Brazil
[4] New Jersey Inst Technol, Newark, NJ 07103 - USA
[5] NASA, Ames Res Ctr, Mountain View, CA 94040 - USA
Número total de Afiliações: 5
Tipo de documento: Artigo Científico
Fonte: ASTROPHYSICAL JOURNAL; v. 819, n. 2 MAR 10 2016.
Citações Web of Science: 28
Resumo

Rotational shear layers at the boundary between radiative and convective zones, tachoclines, play a key role in the process of magnetic field generation in solar-like stars. We present two sets of global simulations of rotating turbulent convection and dynamo. The first set considers a stellar convective envelope only; the second one, aiming at the formation of a tachocline, also considers the upper part of the radiative zone. Our results indicate that the resulting properties of the mean flows and dynamo, such as the growth rate, saturation energy, and mode, depend on the Rossby number (Ro). For the first set of models either oscillatory (with similar to 2 yr period) or steady dynamo solutions are obtained. The models in the second set naturally develop a tachocline, which in turn leads to the generation of a strong mean magnetic field. Since the field is also deposited in the stable deeper layer, its evolutionary timescale is much longer than in the models without a tachocline. Surprisingly, the magnetic field in the upper turbulent convection zone evolves on the same timescale as the deep field. These models result in either an oscillatory dynamo with a similar to 30 yr period or a steady dynamo depending on Ro. In terms of the mean-field dynamo coefficients computed using the first-order smoothing approximation, the field evolution in the oscillatory models without a tachocline seems to be consistent with dynamo waves propagating according to the Parker-Yoshimura sign rule. In the models with tachoclines the dynamics is more complex and involves other transport mechanisms as well as tachocline instabilities. (AU)

Processo FAPESP: 13/11679-4 - Campos magnéticos cósmicos: dos mecanismos de geração à atividade solar e a conexão Terra-Sol
Beneficiário:Gustavo Andres Guerrero Eraso
Linha de fomento: Bolsas no Brasil - Pós-Doutorado
Processo FAPESP: 09/54006-4 - Um cluster de computadores para o Departamento de Astronomia do IAG-USP e para o Núcleo de Astrofísica da UNICSUL
Beneficiário:Elisabete Maria de Gouveia Dal Pino
Linha de fomento: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
Processo FAPESP: 13/10559-5 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, simulações numéricas, observações e desenvolvimento de instrumentação para o Cherenkov Telescope Array (CTA)
Beneficiário:Elisabete Maria de Gouveia Dal Pino
Linha de fomento: Auxílio à Pesquisa - Temático