Multi-point magnetic flux rope analysis for the 2020 April 19 CME observed in situ by Solar Orbiter and Wind

Abstract:

We present the results of an analysis for the magnetic field measurements for the first CME observed by Solar Orbiter on 2020 April 19 using our 3D Coronal Rope Ejection (3DCORE) model. The model assumes an empirically motivated torus-like flux rope structure that expands self-similarly within the heliosphere, while influenced by a simplified interaction with the solar wind environment and carries along an embedded analytical magnetic field. We then combine the 3DCORE model with a Monte-Carlo based Bayesian inference algorithm (ABC-SMC) in order to fit the CME flux ropes and obtain error estimates for the parameters of our model. The same CME was also observed on April 20, a day later compared to Solar Orbiter, at the L1 point by the DSCOVR and Wind satellites, at a significant separation in radial distance (0.2 AU), and at a small longitudinal separation of 5 degree. This gives us the rare opportunity to perform a multi-point fitting analysis for both measurements. For this purpose, we modified our fitting technique so that it is capable of fitting both flux rope signatures simultaneously. This allows us to better verify the 3DCORE model on larger scales with respect to the magnetic field. Furthermore, we can measure the additional accuracy that is obtained by combining both measurements instead of using each on their own.