Abstract
Abstract Over a four hour period between 2014 June 12–13 a series of three flares were observed within AR 12087. This sequence of flares started with a non-eruptive M-class flare, followed by a non-eruptive C-class flare, and finally ended with a second C-class flare that had an associated filament eruption. In this paper we combine spectroscopic analysis of Interface Region Imaging Spectrometer observations of the Si iv line during the three flares along with a series of nonlinear force-free field (NLFFF) extrapolations in order to investigate the conditions that lead the final flare to be eruptive. From this analysis it is found to be unlikely that the eruption was triggered by either kink instability or by tether-cutting reconnection, allowing the flux rope to rise into a region where it would be susceptible to the torus instability. The NLFFF modeling does, however, suggest that the overlying magnetic field has a fan-spine topology, raising the possibility that breakout reconnection occurring during the first two flares weakened the overlying field, allowing the flux rope to erupt in the subsequent third flare.
Highlights
Several decades of research both observational and theoretical have revealed a number of different processes and mechanisms through which solar flares and their associated eruptions can be triggered
It is important to note that while three flares are present in this lightcurve, the middle flare does not correspond to the second flare produced by active region (AR) 12087, but corresponds to an M 3.1 flare produced by AR 12085, situated in the lower western quadrant of the solar disk
What we find is that Sribbon/Sspot is smallest for the eruptive flare, counter to the conclusions of Toriumi et al (2017) who found that in general Sribbon/Sspot is larger for eruptive flares
Summary
Several decades of research both observational and theoretical have revealed a number of different processes and mechanisms through which solar flares and their associated eruptions can be triggered. Sequential flaring can provide an excellent test of flaretrigger models allowing us to investigate whether all flares in the sequence are triggered by the same process, and, whether there are consistent pre-flare signatures. Examples of this kind of study can be found in Nitta & Hudson (2001), Romano et al (2015), and Polito et al (2017).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
