Tracking a magnetic flux tube: from the Sun to the interplanetary medium

NAKWACKI M.S.; DASSO, S.; DEMOULIN, P.; MANDRINI, C. H.; GULISANO A.M.

mar del plata

Conferencia; 55ª Reunión Anual de la Asociación Argentina de Astronomía; 2012

Asociación argentina de astronomía

The interplanetary medium is filled with a low density plasma, the solar wind, that flows fromthe Sun. This wind transports the magnetic structures that are ejected from the solar corona (e.g.coronal mass ejections, CMEs). We study from a theoretical and observational point of view someaspects of the evolution of a particular CME in the interplanetary medium, a magnetic cloud observedin 1998 at 1 astronomical unit (AU) and at 5.4 AU. We model the dynamical evolution of this eventbased on a magnetohydrodynamic description of the plasma proposing a self similar evolution withdifferent expansion rates in each of their main directions. We quantify their expansion and we computethe global invariant quantities (flux, magnetic helicity and magnetic energy) that are relevant to acombined analysis of solar events and their interplanetary counterparts. From solar observations ofthe sources, we quantify the magnetic flux involved in the ejection and the magnetic helicity variationof the source active region. We follow the evolution of the above mentioned MC from its solar source,until farther than 5 AU providing an interpretation for the distorsion of the structure due to itsinteraction with the solar wind far from the Sun.