IAFE   05512
INSTITUTO DE ASTRONOMIA Y FISICA DEL ESPACIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Combined study of solar magnetic flux tubes eruptions and their interplanetary manifestation
Autor/es:
NAKWACKI, M. S.
Lugar:
São Paulo
Reunión:
Seminario; Seminários do Departamento de Astronomia IAG/USP; 2010
Resumen:
The interplanetary medium is filled with a low density plasma that
flows from the Sun and is called the solar wind. This wind transports
the magnetic structures that are ejected from the solar corona (e.g.
coronal mass ejections, CMEs). In this Thesis, we study from a
theoretical and observational point of view some aspects of the
evolution of CMEs in the interplanetary medium; in particular, of a
subset called magnetic clouds (MCs). We model the dynamical evolution of
several events that occurred between 1997 and 2004, we quantify their
expansion and we compute, using models developed as part of this Thesis,
the global invariant quantities (flux and magnetic helicity) that are
relevant to a combined analysis of solar events and their interplanetary
counterparts. The models we develop are based in a magnetohydrodynamic
description of the plasma. We propose a self similar evolution for the
cloud structures with different expansion rates in each of their main
directions (radial and axial). We start considering only a radial
expansion and we proceed to include an axial expansion. Finally, we
broaden the description towards a more general formalism, based on
observations, that is derived in a hierarchical order and can be applied
to more general structures. We show the robustness of global invariants
when computed using different expansion models. We quantify for the
first time the typical amount of energy lost per unit time in the
evolution of a MC. For some of the studied MCs we also analyze
observations of the associated solar event and of its source active
region. We identify the characteristics of the eruptive regions that
allow us to quantify the global invariants in the Sun. We quantify the
magnetic flux involved in the ejection and the magnetic helicity
variation of the source active region. Finally, we study the evolution
of a particular MC from its observation close to Earth until farther
than 5 astronomical units using data from two spacecraft aligned with
the Sun. We quantify the global invariants in both observational points.
We compare these quantities and we provide an interpretation for the
origin of the magnetic structure distorted because of its interaction
with the solar wind far from the Sun. We extend this comparison to the
Sun and we identify the solar source, in this way we achieve a complete
description of the MC evolution along the heliosphere.