INVESTIGADORES
LOPEZ FUENTES Marcelo Claudio
artículos
Título:
A Relationship Between Transition Region Brightenings, Abundances, and Magnetic Topology
Autor/es:
L. FLETCHER; M. C. LÓPEZ FUENTES; C. H. MANDRINI; B. SCHMIEDER; P. DÉMOULIN; H. MASON; P. YOUNG; N. NARIAKI
Revista:
SOLAR PHYSICS
Editorial:
Kluwer Academic Publishers
Referencias:
Año: 2001 vol. 203 p. 255 - 287
ISSN:
0038-0938
Resumen:
We present multi-instrument observations of active region (AR) 8048,
made between 3 June and 5 June 1997, as part of the SOHO Joint Observing
Program 33. This AR has a sigmoid-like global shape and undergoes
transient brightenings in both soft X-rays and transition region (TR)
lines. We compute a magneto-hydrostatic model of the AR magnetic field,
using as boundary condition the photospheric observations of SOHO/MDI.
The computed large-scale magnetic field lines show that the large-scale
sigmoid is formed by two sets of coronal loops. Shorter loops,
associated with the core of the SXT emission, coincide with the loops
observed in the hotter CDS lines. These loops reveal a gradient of
temperature, from 2 MK at the top to 1 MK at the ends. The field lines
most closely matching these hot loops extend along the quasi-separatrix
layers (QSLs) of the computed coronal field. The TR brightenings
observed with SOHO/CDS can also be associated with the magnetic field
topology, both QSL intersections with the photosphere, and places where
separatrices issuing from bald patches (sites where field lines coming
from the corona are tangent to the photosphere) intersect the
photosphere. There are, furthermore, suggestions that the element
abundances measured in the TR may depend on the type of topological
structure present. Typically, the TR brightenings associated with QSLs
have coronal abundances, while those associated with BP separatrices
have abundances closer to photospheric values. We suggest that this
difference is due to the location and manner in which magnetic
reconnection occurs in two different topological structures.