Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot

We study the flaring activity in a nest of sunspots in which two bipolar regions emerge inside a third one. These bipolar regions belong to a large complex of activity (McMath 15314) formed by five bipoles on its May 1978 rotation. The usual spreading action during the growth of the bipoles leads to...

Descripción completa

Guardado en:
Detalles Bibliográficos
Publicado: 1998
Materias:
Magnetic fields
MHD
Sun: corona
Sun: flares
Sun: magnetic fields
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v332_n1_p353_Gaizauskas
http://hdl.handle.net/20.500.12110/paper_00046361_v332_n1_p353_Gaizauskas
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00046361_v332_n1_p353_Gaizauskas
record_format dspace
spelling paper:paper_00046361_v332_n1_p353_Gaizauskas2025-07-30T17:10:53Z Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot Magnetic fields MHD Sun: corona Sun: flares Sun: magnetic fields We study the flaring activity in a nest of sunspots in which two bipolar regions emerge inside a third one. These bipolar regions belong to a large complex of activity (McMath 15314) formed by five bipoles on its May 1978 rotation. The usual spreading action during the growth of the bipoles leads to the formation of a δ-configuration: the preceding and following spots of the two interior regions overlap (p-f collision) into a single penumbra. While δ-configurations created in this way normally favor strong flaring activity, only very small flares occur during 5 days. Only when the following umbra in the δ-spot breaks into pieces, accompanied by rapid photospheric motions, do intense flares occur. The largest and best observed one in this sequence, a class 1B/X1 flare on 28 May 1978, is remarkable for the absence of ejecta and for the concentration of its emission in three widely spaced sites, a pattern which holds in general over two days for lesser flares. We take this pattern as evidence that the flare is confined to the low corona. We first compute the coronal magnetic field using subphotospheric sources to model the observed magnetic data and derive the location of separatrices. In this case the magnetic field topology is defined by the link between these discrete sources. The relevant generalization of separatrices in any kind of magnetic configuration are 'quasi-separatrix layers' (QSLs). We calculate them using the previous model, but also for a model obtained with a more classical extrapolation technique based on the fast Fourier transform method. We show, with both approaches, that the plage brightenings during the quiescent phase of the region and the flare kernels are located at the intersection of separatrices and QSLs with the photosphere. Moreover, they are magnetically linked. Bright and dark 'post'-flare loops which form in the maximum and gradual phases of the IB/X1 flare also highlight the location of the separatrices and the QSLs. This confirms previous studies on the importance of the magnetic field topology for flares and, with this study, we further constrain the underlying physical mechanism. We draw some conclusions about the role of magnetic reconnection in the solar corona; depending on the photospheric conditions that we identify, reconnection can lead to steady heating or flaring. 1998 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v332_n1_p353_Gaizauskas http://hdl.handle.net/20.500.12110/paper_00046361_v332_n1_p353_Gaizauskas
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Magnetic fields
MHD
Sun: corona
Sun: flares
Sun: magnetic fields
spellingShingle Magnetic fields
MHD
Sun: corona
Sun: flares
Sun: magnetic fields
Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot
topic_facet Magnetic fields
MHD
Sun: corona
Sun: flares
Sun: magnetic fields
description We study the flaring activity in a nest of sunspots in which two bipolar regions emerge inside a third one. These bipolar regions belong to a large complex of activity (McMath 15314) formed by five bipoles on its May 1978 rotation. The usual spreading action during the growth of the bipoles leads to the formation of a δ-configuration: the preceding and following spots of the two interior regions overlap (p-f collision) into a single penumbra. While δ-configurations created in this way normally favor strong flaring activity, only very small flares occur during 5 days. Only when the following umbra in the δ-spot breaks into pieces, accompanied by rapid photospheric motions, do intense flares occur. The largest and best observed one in this sequence, a class 1B/X1 flare on 28 May 1978, is remarkable for the absence of ejecta and for the concentration of its emission in three widely spaced sites, a pattern which holds in general over two days for lesser flares. We take this pattern as evidence that the flare is confined to the low corona. We first compute the coronal magnetic field using subphotospheric sources to model the observed magnetic data and derive the location of separatrices. In this case the magnetic field topology is defined by the link between these discrete sources. The relevant generalization of separatrices in any kind of magnetic configuration are 'quasi-separatrix layers' (QSLs). We calculate them using the previous model, but also for a model obtained with a more classical extrapolation technique based on the fast Fourier transform method. We show, with both approaches, that the plage brightenings during the quiescent phase of the region and the flare kernels are located at the intersection of separatrices and QSLs with the photosphere. Moreover, they are magnetically linked. Bright and dark 'post'-flare loops which form in the maximum and gradual phases of the IB/X1 flare also highlight the location of the separatrices and the QSLs. This confirms previous studies on the importance of the magnetic field topology for flares and, with this study, we further constrain the underlying physical mechanism. We draw some conclusions about the role of magnetic reconnection in the solar corona; depending on the photospheric conditions that we identify, reconnection can lead to steady heating or flaring.
title Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot
title_short Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot
title_full Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot
title_fullStr Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot
title_full_unstemmed Interactions between nested sunspots. II. A confined X1 flare in a delta-type sunspot
title_sort interactions between nested sunspots. ii. a confined x1 flare in a delta-type sunspot
publishDate 1998
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v332_n1_p353_Gaizauskas
http://hdl.handle.net/20.500.12110/paper_00046361_v332_n1_p353_Gaizauskas
_version_ 1840326042401636352

Ejemplares similares