On Modeling Flux Rope-type Small Interplanetary Transients by Non-Force Free Methods

Wednesday, 17 December 2014
Wenyuan Yu1, Charles J Farrugia1, NoƩ Lugaz1, Antoinette Broe Galvin2, Martin Leitner3, Christian Moestl4, Teresa Nieves-Chinchilla5, Janet G Luhmann6 and Lynn B Wilson III5, (1)University of New Hampshire Main Campus, Durham, NH, United States, (2)Univ of New Hampshire, Durham, NH, United States, (3)Institute of Physics, University of Graz, Graz, Austria, (4)Space Research Institute, Austrian Academy of Sciences, Graz, Austria, Graz, Austria, (5)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (6)University of California Berkeley, Berkeley, CA, United States
Small interplanetary transients can have the geometry of magnetic flux ropes. We show examples of these taken from STEREO and Wind observations. We then model these configurations using techniques which do not assume a force-free state. We do this because past work (Wenyuan et al., 2014) has shown statistically over a large sample that the ratio of the thermal (proton plus electron) pressure to the magnetic pressure, i.e., the plasma beta, can be of order unity. We apply two methods, one analytical and one based on Grad-Shafranov reconstruction. We then discuss and interpret the results obtained from this least-squares fitting approach. We also consider the results in the context of a comparison with what one would obtain from a linear force-free algorithm (Lundquist solution).