SELF-ASSEMBLY OF SHALLOW MAGNETIC SPOTS THROUGH STRONGLY STRATIFIED TURBULENCE
2013 (English)In: Astrophysical journal. Letters, ISSN 2041-8205, Vol. 776, no 2, L23- p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2013. Vol. 776, no 2, L23- p.
magnetohydrodynamics (MHD), starspots, sunspots, turbulence
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-95742DOI: 10.1088/2041-8205/776/2/L23ISI: 000325490200006OAI: oai:DiVA.org:su-95742DiVA: diva2:662334