EXPLOSIVE CHROMOSPHERIC EVAPORATION IN A CIRCULAR-RIBBON FLARE

ABSTRACT In this paper, we report our multiwavelength observations of the C4.2 circular-ribbon flare in active region (AR) 12434 on 2015 October 16. The short-lived flare was associated with positive magnetic polarities and a negative polarity inside, as revealed by the photospheric line-of-sight ma...

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Bibliographic Details
Published in:The Astrophysical journal 2016-08, Vol.827 (1), p.27-27
Main Authors: Zhang, Q. M., Li, D., Ning, Z. J., Su, Y. N., Ji, H. S., Guo, Y.
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Blowouts
CHROMOSPHERE
Circularity
COSMIC ELECTRONS
EVAPORATION
Flares
GAMMA RADIATION
HARD X RADIATION
Line of sight
MAGNETIC RECONNECTION
Photosphere
PLASMA
Polarity
Ribbons
SOLAR CORONA
SOLAR FLARES
SUN
Sun: chromosphere
Sun: corona
Sun: flares
Sun: X-rays, gamma-rays
techniques: spectroscopic
VELOCITY
X-RAY SOURCES
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Summary:ABSTRACT In this paper, we report our multiwavelength observations of the C4.2 circular-ribbon flare in active region (AR) 12434 on 2015 October 16. The short-lived flare was associated with positive magnetic polarities and a negative polarity inside, as revealed by the photospheric line-of-sight magnetograms. Such a magnetic pattern is strongly indicative of a magnetic null point and spine-fan configuration in the corona. The flare was triggered by the eruption of a mini-filament residing in the AR, which produced the inner flare ribbon (IFR) and the southern part of a closed circular flare ribbon (CFR). When the eruptive filament reached the null point, it triggered null point magnetic reconnection with the ambient open field and generated the bright CFR and a blowout jet. Raster observations of the Interface Region Imaging Spectrograph show plasma upflow at speeds of 35-120 km s−1 in the Fe xxi λ1354.09 line ( ) and downflow at speeds of 10-60 km s−1 in the Si iv λ1393.77 line ( ) at certain locations of the CFR and IFR during the impulsive phase of the flare, indicating explosive chromospheric evaporation. Coincidence of the single hard X-ray source at 12-25 keV with the IFR and calculation based on the thick-target model suggest that the explosive evaporation was most probably driven by nonthermal electrons.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/827/1/27