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CDS UV Brightenings Explained by Quasi-separatrices and Bald Patches in an S-shape Active Region

Published online by Cambridge University Press:  13 May 2016

B. Schmieder ,
P. Démoulin ,
L. Fletcher ,
M. C. López Fuentes ,
C. H. Mandrini ,
H. E. Mason ,
P. R. Young  and
N. Nitta
B. Schmieder
Affiliation:
Observatoire de Paris, 92195 Meudon, Cedex Principal, France
P. Démoulin
Affiliation:
Observatoire de Paris, 92195 Meudon, Cedex Principal, France
L. Fletcher
Affiliation:
Lockheed Martin Solar and Astrophysics Lab., Org L9-41, B252, 2351 Hanover Street, Palo Alto CA 94306, US
M. C. López Fuentes
Affiliation:
Instituto de Astronomía y Física del Espacio, IAFE, CC67, Suc28, 1428 Buenos Aires, Argentina
C. H. Mandrini
Affiliation:
Instituto de Astronomía y Física del Espacio, IAFE, CC67, Suc28, 1428 Buenos Aires, Argentina
H. E. Mason
Affiliation:
Department of Applied Mathematics and Theoretical Physics, Cambridge University, Silver Street, Cambridge CA, UK
P. R. Young
Affiliation:
Department of Applied Mathematics and Theoretical Physics, Cambridge University, Silver Street, Cambridge CA, UK
N. Nitta
Affiliation:
Lockheed Martin Solar and Astrophysics Lab., Org L9-41, B252, 2351 Hanover Street, Palo Alto CA 94306, US

Abstract

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We present multi-instrument observations of AR 8048, made between June 3 and June 5 1997 as part of SoHO JOP033. This active region (AR) has a sigmoid-like global shape and undergoes transient brightenings through which the stored energy is released.

Using a magneto-hydrostatic model, we compute coronal magnetic field. The large-scale magnetic lines confirm the sigmoidal characteristics of the AR. The field lines most closely matching the hotter SoHO/CDS loops extend along the quasi-separatrix-Iayers (QSLs) of the coronal field. Transition region (TR) brightenings observed with SoHO/CDS can be associated with both QSL intersections with the photosphere, and places where separatrices corresponding to bald patches (BPs, sites where field lines are tangent to the photosphere) lie at the photospheric plane. There are suggestions that the element abundances measured in the TR may depend on the type of topological structure present. TR brightenings associated with QSLs have coronal abundances, while those associated with BP separatrices have abundances closer to photospheric values.

Type
Session III: Active Region Structure and Dynamics
Information
Symposium - International Astronomical Union , Volume 203: Recent Insights into the Physics of the Sun and Heliosphere: Highlights from Soho and Other Space Missions , 2001 , pp. 314 - 317
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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