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GREGOR observations of a small flare above a sunspot

Published online by Cambridge University Press:  09 September 2016

M. Sobotka
Affiliation:
Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165 Ondřejov, Czech Republic email: [email protected]
J. Dudík
Affiliation:
Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165 Ondřejov, Czech Republic email: [email protected]
C. Denker
Affiliation:
Leibniz Institute for Astrophysics Potsdam, An der Sternwarte 16, 14482 potsdam, Germany
H. Balthasar
Affiliation:
Leibniz Institute for Astrophysics Potsdam, An der Sternwarte 16, 14482 potsdam, Germany
J. Jurčák
Affiliation:
Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165 Ondřejov, Czech Republic email: [email protected]
W. Liu
Affiliation:
Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165 Ondřejov, Czech Republic email: [email protected]
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Abstract

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A small flare ribbon above a sunspot umbra in active region 12205 was observed on November 7, 2014, at 12:00 UT in the blue imaging channel of the 1.5-m GREGOR telescope, using a 0.1 nm Ca II H interference filter. Context observations from SDO/AIA, Hinode/SOT, and IRIS show that the ribbon is a part of a larger one that extends through the neighboring positive polarities and also participates in several other flares within the active region. A 140 second long time series of Ca II H images was reconstructed by means of the Multi-Frame Blind Deconvolution method, giving the respective spatial and temporal resolutions of 0”.1 and 1 s. Light curves and horizontal velocities of small-scale bright knots in the observed flare ribbon were measured. Some knots are stationary but three move along the ribbon with speeds of 7–11 km s−1. Two of them move in the opposite direction and exhibit highly correlated intensity changes, providing evidence for the presence of slipping reconnection at small spatial scales.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2016 

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