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Delta spots and great flares

Zirin, Harold and Liggett, Margaret A. (1987) Delta spots and great flares. Solar Physics, 113 (1-2). pp. 267-283. ISSN 0038-0938. doi:10.1007/bf00147707.

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Using eighteen years of observations at Big Bear, we summarize the development of δ spots and the great flares they produce. We find δ groups to develop in three ways: eruption of a single complex active region formed below the surface, eruption of large satellite spots near (particularly in front of) a large older spot, or collision of spots of opposite polarity from different dipoles. Our sample of twenty-one δ spots shows that once they lock together, they never separate, although rarely an umbra is ejected. The δ spots are already disposed to their final form when they emerge. The driving force for the shear is spot motion, either flux emergence or the forward motion of p spots in an inverted magnetic configuration.

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Additional Information:© 1987 by D. Reidel Publishing Company. Published 01 January 1987. This work was supported by NASA under NGL 05-002-034, the NSF under ATM-8513577, and the AFOSR through AFOSR-87-0034. We are grateful to the Big Bear staff for gathering the data, and to Prof. K. Tanaka for many useful discussions.
Funding AgencyGrant Number
NASANGL 05 002 034
Air Force Office of Scientific Research (AFOSR)AFOSR-87-0034
Subject Keywords:Flare; Fibril; Active Region; Opposite Polarity; Forward Motion
Issue or Number:1-2
Record Number:CaltechAUTHORS:20200602-123444467
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Official Citation:Zirin, H., Liggett, M.A. Delta spots and great flares. Sol Phys 113, 267–283 (1987).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103637
Deposited By: Tony Diaz
Deposited On:02 Jun 2020 20:15
Last Modified:16 Nov 2021 18:23

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