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Astron. Astrophys. 329, 1138-1144 (1998)

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Interpreting the growth and destruction of a large long-duration solar active-region complex

V. Bumba 1, A. Garcia 2 and S. Jordan 3

1 Astronomical Institute, Academy of Sciences of the Czech Republic, CR-251 65 Ondejov, Czech Republic
2 Observatório Astronómico Universidade de Coimbra Santa Clara, 3040 Coimbra, Portugal
3 Laboratory for Astronomy and Solar Physics Goddard Space Flight Center, Greenbelt, MD, USA

Received 9 September 1996 / Accepted 3 September 1997

Abstract

In a companion paper, we show that the large limb flare and coronal mass ejection of July 9, 1982, and other energetic events that followed through September 4, 1982, represent the final phase in the evolution of a large active-region complex (Jordan et al. 1997).

In this paper, we review the long-duration evolution of this complex. We begin by showing that, before its final phase, new activity in the form of renewed flux continued to appear for nearly two years, progressively complicating the field topology. Observations suggest that the source of this flux rotated almost as a rigid body. Evidence is presented that, during the final phase of large-scale eruptions, either the connection with the underlying source of flux is broken, or the source itself has changed. After the flare and CME of September 4, 1982, the magnetic field topology of the entire complex was greatly simplified, and the area of former activity was replaced by a large coronal hole. We conclude that this evolution and destruction of a large long-duration active-region complex is a characteristic feature of how the global magnetic field of the Sun changes during the solar cycle.

Key words: Sun: magnetic field – Sun: activity – Sun: coronal hole – Sun: flares

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© European Southern Observatory (ESO) 1998

Online publication: December 16, 1997
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