Details

Autor(en) / Beteiligte

• Sun, Xudong
• Hoeksema, J Todd
• Liu, Yang
• Aulanier, Guillaume
• SU, YINGNA
• Hannah, Iain G
• Hock, Rachel A

Titel

HOT SPINE LOOPS AND THE NATURE OF A LATE-PHASE SOLAR FLARE

Ist Teil von

• The Astrophysical journal, 2013-12, Vol.778 (2), p.1-17

Ort / Verlag

United States: American Astronomical Society

Erscheinungsjahr

2013

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• The fan-spine magnetic topology is believed to be responsible for many curious features in solar explosive events. A spine field line links distinct flux domains, but direct observation of such a feature has been rare. Here we report a unique event observed by the Solar Dynamic Observatory where a set of hot coronal loops (over 10 MK) connected to a quasi-circular chromospheric ribbon at one end and a remote brightening at the other. Magnetic field extrapolation suggests that these loops are partly tracers of the evolving spine field line. Continuous slipping- and null-point-type reconnections were likely at work, energizing the loop plasma and transferring magnetic flux within and across the fan quasi-separatrix layer. We argue that the initial reconnection is of the "breakout" type, which then transitioned to a more violent flare reconnection with an eruption from the fan dome. Significant magnetic field changes are expected and indeed ensued. This event also features an extreme-ultraviolet (EUV) late phase, i.e., a delayed secondary emission peak in warm EUV lines (about 2-7 MK). We show that this peak comes from the cooling of large post-reconnection loops beside and above the compact fan, a direct product of eruption in such topological settings. The long cooling time of the large arcades contributes to the long delay; additional heating may also be required. Our result demonstrates the critical nature of cross-scale magnetic coupling-topological change in a sub-system may lead to explosions on a much larger scale.