SIMULATING THE FORMATION OF A SIGMOIDAL FLUX ROPE IN AR10977 FROMSOHO/MDI MAGNETOGRAMS

Abstract

The modeling technique of Mackay et al. is applied to simulate the coronal magnetic field of NOAA active region AR10977 over a seven day period (2007 December 2-10). The simulation is driven with a sequence of line-of-sight component magnetograms from SOHO/MDI and evolves the coronal magnetic field though a continuous series of non-linear force-free states. Upon comparison with Hinode/XRT observations, results show that the simulation reproduces many features of the active region's evolution. In particular, it describes the formation of a flux rope across the polarity inversion line during flux cancellation. The flux rope forms at the same location as an observed X-ray sigmoid. After five days of evolution, the free magnetic energy contained within the flux rope was found to be 3.9 × 10 30 erg. This value is more than sufficient to account for the B1.4 GOES flare observed from the active region on 2007 December 7. At the time of the observed eruption, the flux rope was found to contain 20% of the active region flux. We conclude that the modeling technique proposed in Mackay et al.-which directly uses observed magnetograms to energize the coronal field-is a viable method to simulate the evolution of the coronal magnetic field.

Transition from eruptive to confined flares in the same active region

“…Structures compatible with magnetic flux ropes have been observed on an active region scale (Canou & Amari 2010;Jing et al 2010;Guo et al 2010b;Green et al 2011;Savcheva et al 2012;Gibb et al 2014;Jiang et al 2014) and on a larger scale in coronal cavities (Gibson et al 2010;Rachmeler et al 2013;Gibson 2015;Bak-Steslicka et al 2016). The standard flare model requires a mechanism that triggers the onset of the flux rope eruption, resulting in the phenomenology observed during solar flares.…”

“…Structures compatible with magnetic flux ropes have been observed on an active region scale (Canou & Amari 2010;Jing et al 2010;Guo et al 2010b;Green et al 2011;Savcheva et al 2012;Gibb et al 2014;Jiang et al 2014) and on a larger scale in coronal Article published by EDP Sciences A26, page 1 of 11 A&A 601, A26 (2017) …”

The Relation Between Solar Eruption Topologies and Observed Flare Features. Ii. Dynamical Evolution

“…Kliem et al (2013) already showed that our unstable models evolve through these stages in the MHD sense, but here for the first time we show that an MF simulation is sufficient to look at the evolution of several flare features. And since data-constrained and even data-driven MF simulations (e.g., Gibb et al 2014) are much faster than dataconstrained and the non-existent data-driven MHD simulations, n = 70,000 n = 110,000 The iteration number of the models from which we have taken these field lines is marked on the corresponding plots. The magnetic flux distribution is shown with red (positive) and green (negative) contours.…”

Flux Emergence (Theory)

“…In the work of Cheung and DeRosa (2012), the evolution of AR 11158 was modeled by driving the simulation with a temporal sequence of magnetograms to capture the AR from emergence to eruption (Gibb et al, 2014, used a similar approached for modeling AR 10977). This was motivated by previous studies using the MF approach to model the evolution of the global corona (Yeates et al, 2007(Yeates et al, , 2008Yeates and Mackay, 2009a,b;Yeates et al, 2010).…”