NSF Award
1560411
Solar eruptive phenomena, such as Coronal Mass Ejections (CMEs) and flares, cause some of the most severe space-weather effects. They are believed to result from an explosive release of magnetic energy in the solar corona, where the magnetic field cannot at present be measured directly. This research project is expected to lead to a better modeling and deeper understanding of the physical drivers of space weather. A physics-based understanding of the underlying cause(s) of CMEs can eventually lead to a better forecasting of space-weather events, which may allow mitigating steps to be taken to protect human and technological assets. To model solar eruptive phenomena, it is critical to have an efficient method for numerically constructing pre-eruptive configurations from photospheric magnetic data. The new method to be developed over the course of this project is expected to be highly competitive compared to the existing ones, such as the nonlinear force-free field reconstruction, or flux-rope insertion, especially in terms of the efficiency and control of the resulting flux-rope parameters. This investigation is timely, feasible, and directly related to the NSF's Solar Terrestrial Research Program that "supports research on the processes by which energy in diverse forms is generated by the Sun, transported to the Earth, and ultimately deposited in the terrestrial environment." Therefore, the project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research. <br/><br/>To date, analytical or semi-analytical flux-rope models are being used as the basis for the eruption in many of these models. This 3-year project aims to construct analytically approximate solutions of a force-free flux rope of flexible shape embedded in an ambient potential field, with photosphere flux distribution matching the observed fields. The near-equilibrium analytic solution will be relaxed further with line-tied MHD simulations to reach an approximate numerical stable equilibrium as the initial state for MHD simulations (with further driving) of realistic CME events. The project will improve upon the current Titov-Demoulin (TD) force-free flux rope model the PI has developed to allow for the flexibility of complex shapes/paths of the flux rope and preserve the flux distribution in the observed magnetograms. The computation of pre-eruptive configurations based on this technique will be simple, highly efficient, and the resulting model will be significantly more accurate than those used in CME simulations so far. As part of this investigation, the project team will provide formulas and a numerical code for producing equilibrium flux ropes, so that other researchers from the solar-heliospheric community will be able to experiment using these models in their own codes.
