Statistical Properties of Ribbon Evolution and Reconnection Electric Fields in Eruptive and Confined Flares

Abstract

A statistical study of the chromospheric ribbon evolution in H two-ribbon flares was performed. The data set consists of 50 confined (62%) and eruptive (38%) flares that occurred from June 2000 to June 2015. The flares were selected homogeneously over the H and Geostationary Operational Environmental Satellite (GOES) classes, with an emphasis on including powerful confined flares and weak eruptive flares. H filtergrams from the Kanzelhöhe Observatory in combination with Michelson Doppler Imager (MDI) and Helioseismic and Magnetic Imager (HMI) magnetograms were used to derive the ribbon separation, the ribbon-separation velocity, the magnetic-field strength, and the reconnection electric field. We find that eruptive flares reveal statistically larger ribbon separation and higher ribbon-separation velocities than confined flares. In addition, the ribbon separation of eruptive flares correlates with the GOES SXR flux, whereas no clear dependence was found for confined flares. The maximum ribbon-separation velocity is not correlated with the GOES flux, but eruptive flares reveal on average a higher ribbon-separation velocity (by ≈ 10 km s−1). The local reconnection electric field of confined () and eruptive () flares correlates with the GOES flux, indicating that more powerful flares involve stronger reconnection electric fields. In addition, eruptive flares with higher electric-field strengths tend to be accompanied by faster coronal mass ejections.Electronic Supplementary MaterialThe online version of this article (10.1007/s11207-018-1253-1) contains supplementary material, which is available to authorized users.

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“…Meanwhile, the rising speed of the X point, i.e., the apex of the cusp structure reaches a maximum of about 40 km s −1 . Our simulated flare-ribbon distances, their separation speed as well as the rising speed of the cusp are all comparable to typical observed ones [52][53][54][55].…”

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“…The transverse expansion of the bottom of cusp, which corresponds to the separation of flare ribbons in observation, goes with a speed of 11 km s −1 , while the leading edge of the CME reaches a speed of ∼ 600 km s −1 . All these apparent motions are quantitatively comparable to observed values in typical eruptive flares [39,40,41].…”

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“…Hα data are in particular used for the study of energetic events such as solar flares (e.g. Wang et al, 2003;Veronig et al, 2006b;Vršnak et al, 2006b;Miklenic et al, 2007;Pötzi et al, 2015;Thalmann et al, 2015;Joshi et al, 2017;Temmer et al, 2017;Hinterreiter et al, 2018;Tschernitz et al, 2018), filament eruptions and dynamics (e.g. Maričić et al, 2004;Möstl et al, 2009;Zuccarello et al, 2012;Su et al, 2012;Filippov, 2013;Yardley et al, 2016;Aggarwal et al, 2018), Moreton waves (e.g.…”