Flare-related magnetic anomaly with a sign reversal

Document Type

Article

Publication Date

12-10-2003

Abstract

In this paper we report a significant magnetic anomaly, specifically an apparent sign reversal of magnetic polarities in small areas of Michelson Doppler Imager (MDI) magnetograms during the impulsive phase of an X5.6 flare on 2001 April 6. Three flare kernels were observed to emit ≥50 keV hard X-rays, which are located in strong magnetic fields of order ± 1000-1500 G. We find that the apparent sign reversal began and persisted for a few minutes in all three kernels, in precise temporal and spatial correspondence with the hard X-ray sources. We search for a combination of instrumental and flare-induced line profile effects that can account for this behavior. Our studies provide a viable scenario that the observed transient sign reversal is likely to be produced by distorted measurements when the Ni I 6768 Å line comes into emission or strong central reversal as a result of nonthermal beam impact on the atmosphere in regions of strong magnetic fields.

Identifier

0346937514 (Scopus)

Publication Title

Astrophysical Journal

External Full Text Location

https://doi.org/10.1086/379146

e-ISSN

15384357

ISSN

0004637X

First Page

615

Last Page

625

Issue

1 I

Volume

599

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