Magnetic Connectivity in the Time-Evolving Heliosphere

The solar magnetic field expands outward from the Sun with the solar wind and fills the heliosphere.  Understanding the structure, dynamics, and connectivity of this field underlies many unanswered questions in solar and heliospheric physics.  In the presence of ideal  flows and in the reference frame co-rotating with the Sun, the solar wind plasma flow is aligned with the magnetic field. In this approximation, tracing the magnetic connectivity of plasma parcels encountered in the heliosphere back to the Sun reveals their solar origin. The magnetic field is also important for the propagation of solar energetic particles (SEPs), guiding them along magnetic field lines from their generation near the Sun to locations in the heliosphere.  Models with varying degrees of complexity are used to estimate the magnetic field connectivity and interpret observations.  A standard approach is to use potential field models to describe the corona, and to ballistically map points in the heliosphere back to the corona with the in situ measured solar wind speed.  More advanced models couple the potential field corona with a heliospheric MHD model.  We test the strengths and limitations of these approaches by utilizing a data-driven time-evolving model of the corona and heliosphere, computed for a month of evolution surrounding the 2024 total solar eclipse.  The time-evolving model is highly dynamic, with many small-scale eruptions.  We treat the time-dependent model as the ``ground truth'' and investigate how well the standard approaches capture the time-varying magnetic connectivity.

Research Supported by NASA and NSF.  Computational resources provided by the NSF ACCESS program and the NASA Advanced Supercomputing division at Ames.