SELF-ASSEMBLY OF SHALLOW MAGNETIC SPOTS THROUGH STRONGLY STRATIFIED TURBULENCE

Brandenburg, AxelKTH,Stockholms universitet,Institutionen för astronomi,Nordiska institutet för teoretisk fysik (Nordita),Nordic Institute for Theoretical Physics NORDITA (author)

AuthorCount:3;
QC 20131107
Recent studies have demonstrated that in fully developed turbulence, the effective magnetic pressure of a large-scale field (non-turbulent plus turbulent contributions) can become negative. In the presence of strongly stratified turbulence, this was shown to lead to a large-scale instability that produces spontaneous magnetic flux concentrations. Furthermore, using a horizontal magnetic field, elongated flux concentrations with a strength of a few percent of the equipartition value were found. Here we show that a uniform vertical magnetic field leads to circular magnetic spots of equipartition field strengths. This could represent a minimalistic model of sunspot formation and highlights the importance of two critical ingredients: turbulence and strong stratification. Radiation, ionization, and supergranulation may be important for realistic simulations, but are not critical at the level of a minimalistic model of magnetic spot formation.

Kleeorin, NathanKTH,Stockholms universitet,Nordiska institutet för teoretisk fysik (Nordita),Ben-Gurion University of the Negev, Israel; N. I. Lobachevsky State University of Nizhny Novgorod, Russia,Nordic Institute for Theoretical Physics NORDITA(Swepub:kth)u10pszpw (author)
Rogachevskii, IgorKTH,Stockholms universitet,Nordiska institutet för teoretisk fysik (Nordita),Ben-Gurion University of the Negev, Israel; N. I. Lobachevsky State University of Nizhny Novgorod, Russia,Nordic Institute for Theoretical Physics NORDITA(Swepub:kth)u1d6noho (author)
Stockholms universitetInstitutionen för astronomi (creator_code:org_t)

By the author/editor: Brandenburg, Axe ...; Kleeorin, Nathan; Rogachevskii, Ig ...

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