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Title: CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS

Abstract

Solar flare emissions in the chromosphere often appear as elongated ribbons on both sides of the magnetic polarity inversion line (PIL), which has been regarded as evidence of a typical configuration of magnetic reconnection. However, flares having a circular ribbon have rarely been reported, although it is expected in the fan-spine magnetic topology involving reconnection at a three-dimensional (3D) coronal null point. We present five circular ribbon flares with associated surges, using high-resolution and high-cadence H{alpha} blue wing observations obtained from the recently digitized films of Big Bear Solar Observatory. In all the events, a central parasitic magnetic field is encompassed by the opposite polarity, forming a circular PIL traced by filament material. Consequently, a flare kernel at the center is surrounded by a circular flare ribbon. The four homologous jet-related flares on 1991 March 17 and 18 are of particular interest, as (1) the circular ribbons brighten sequentially, with cospatial surges, rather than simultaneously, (2) the central flare kernels show an intriguing 'round-trip' motion and become elongated, and (3) remote brightenings occur at a region with the same magnetic polarity as the central parasitic field and are co-temporal with a separate phase of flare emissions. In another flare onmore » 1991 February 25, the circular flare emission and surge activity occur successively, and the event could be associated with magnetic flux cancellation across the circular PIL. We discuss the implications of these observations combining circular flare ribbons, homologous jets, and remote brightenings for understanding the dynamics of 3D magnetic restructuring.« less

Authors:
Publication Date:
OSTI Identifier:
22086262
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 760; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CHROMOSPHERE; ELECTRON EMISSION; ION EMISSION; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIC RECONNECTION; PLASMA JETS; SOLAR CORONA; SOLAR FLARES; SUN; TOPOLOGY

Citation Formats

Haimin, Wang, and Liu Chang, E-mail: haimin.wang@njit.edu. CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS. United States: N. p., 2012. Web. doi:10.1088/0004-637X/760/2/101.
Haimin, Wang, & Liu Chang, E-mail: haimin.wang@njit.edu. CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS. United States. https://doi.org/10.1088/0004-637X/760/2/101
Haimin, Wang, and Liu Chang, E-mail: haimin.wang@njit.edu. 2012. "CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS". United States. https://doi.org/10.1088/0004-637X/760/2/101.
@article{osti_22086262,
title = {CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS},
author = {Haimin, Wang and Liu Chang, E-mail: haimin.wang@njit.edu},
abstractNote = {Solar flare emissions in the chromosphere often appear as elongated ribbons on both sides of the magnetic polarity inversion line (PIL), which has been regarded as evidence of a typical configuration of magnetic reconnection. However, flares having a circular ribbon have rarely been reported, although it is expected in the fan-spine magnetic topology involving reconnection at a three-dimensional (3D) coronal null point. We present five circular ribbon flares with associated surges, using high-resolution and high-cadence H{alpha} blue wing observations obtained from the recently digitized films of Big Bear Solar Observatory. In all the events, a central parasitic magnetic field is encompassed by the opposite polarity, forming a circular PIL traced by filament material. Consequently, a flare kernel at the center is surrounded by a circular flare ribbon. The four homologous jet-related flares on 1991 March 17 and 18 are of particular interest, as (1) the circular ribbons brighten sequentially, with cospatial surges, rather than simultaneously, (2) the central flare kernels show an intriguing 'round-trip' motion and become elongated, and (3) remote brightenings occur at a region with the same magnetic polarity as the central parasitic field and are co-temporal with a separate phase of flare emissions. In another flare on 1991 February 25, the circular flare emission and surge activity occur successively, and the event could be associated with magnetic flux cancellation across the circular PIL. We discuss the implications of these observations combining circular flare ribbons, homologous jets, and remote brightenings for understanding the dynamics of 3D magnetic restructuring.},
doi = {10.1088/0004-637X/760/2/101},
url = {https://www.osti.gov/biblio/22086262}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 760,
place = {United States},
year = {Sat Dec 01 00:00:00 EST 2012},
month = {Sat Dec 01 00:00:00 EST 2012}
}