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Formation of sunspots: theory and observations
  Astronomy and astrophysics

Monday 03 April 2017
from 10:30 to 11:30
at FC61
Speaker : Illa R. Losada (Stockholm University)
Abstract : Sunspots are of basic interest in the solar studies from magnetic fields, as activity counter, to source of coronal mass ejections, flares, and motor of space weather. Still their formation is an unresolved problem in nowadays solar physics. Surface observations depict a 2D structure of the spots at the surface, but it is under debate how to infere deep structures and properties from local helioseismology. From the theoretical point of view, flux tubes theory manages to explain some of the observations, but with some drawbacks, like the magnetic field storage mechanism or the survival of a tube rising in a turbulent media. In this talk I will present another theoretical approach to the formation of sunspots: the negative effective magnetic pressure instability, which is able to concentrate magnetic fields in a turbulent stratified medium. This instability is able suppress turbulence and increase the gas pressure, which drags and concentrate the magnetic fields within. In this framework, sunspots ultimately form within the outermost layers of the Sun. From the observational point of view, I will also present some results and approaches from local helioseismology, where we use Hankel analysis to study the pre-emergence phase of sunspots to try to constraint its deep structures and formation mechanism.

AlbaNova  | Last modified 05 December 2017 10:13  |  HELP