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Title:
Evidence for Current-carrying Emerging Flux
Authors:
Leka, K. D.; Canfield, R. C.; McClymont, A. N.; van Driel-Gesztelyi, L.
Publication:
Astrophysical Journal v.462, p.547 (ApJ Homepage)
Publication Date:
05/1996
Origin:
APJ
Astronomy Keywords:
MAGNETOHYDRODYNAMICS: MHD, SUN: ACTIVITY, SUN: MAGNETIC FIELDS, SUN: SUNSPOTS
DOI:
10.1086/177171
Bibliographic Code:
1996ApJ...462..547L

Abstract

To determine the relationship between electric currents and magnetic flux in emerging sunspots, we use observations of the morphology, proper motion, magnetic flux, and currents associated with several well-observed growing bipoles. Our target was NOAA Active Region 7260, which included a preexisting large spot and a fast-growing area of new magnetic flux. Magnetic bipoles in this region are well documented by X-ray images from the Yohkoh spacecraft and optical images and vector magnetograms from several ground-based observatories.

In this paper we show that (1) the Hα and X-ray structures associated with these bipoles do not agree with potential-field extrapolations of magnetograms; (2) proper motions imply that the flux bundles that make up these new bipoles are twisted before they emerge; (3) these new bipoles are cospatial with significant vertical electric currents; (4) the morphology, proper motion, and measured currents of these bipoles all imply the same sense of twist; (5) this sense of twist is the same as the large-scale twist of the preexisting large spot; and (6) the increase of these currents, as new flux emerges, is not consistent with their generation by photospheric motions.

We conclude that the new magnetic flux that emerged in this active region carried currents generated below the photosphere.

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