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Abstract:
Recently, the Flux Accretion (FA) model of coronal mass ejection (CME) formation was proposed to explain the strong link reported between CME speeds and "ribbon flux" (the amount of photospheric magnetic flux covered by eruptions’ flare ribbons).The FA model quantitatively relates the magnetic flux added to a rising ejection by coronal magnetic reconnection to an increased, net outward Lorentz force on that ejection: reconnection both reduces inward magnetic tension force (consistent with the qualitative Tether Cutting model) and increases the outward hoop force. For both forces, the FA model predicts that the change in force, dF, due to reconnection of an amount of flux dPhi scales as the product (dPhi B), where B is the coronal field strength near the ejection. In addition to explaining the observed correlation between CME speed and ribbon flux, the FA model makes another prediction: the speeds of CMEs should, after accounting for their dependence on ribbon fluxes, be higher for source ARs with higher coronal B at the eruption site. To test this hypothesis, we (1) investigate relationships between coronal field strengths in CME source regions, determined by potential-field extrapolations, and CME speeds, and (2) assess the relative contributions from coronal B and ribbon flux.
