SHINE: How Does Surface Flux Evolution Determine the Structure and Dynamics of the Solar Corona and Inner Heliosphere?

About This Grant

There is a strong connection between the solar corona, which immediately surrounds the Sun and is visible during solar eclipses, and the heliosphere (the space extending further out, until the Sun’s influence terminates). So far we have studied these systems primarily with steady-state descriptions of the corona and heliosphere. In reality this system is constantly evolving. This project will allow us to better understand the coronal/heliosphere system and how it connects with the solar flux evolution. We will study how magnetic field lines are connected, the sources from which the solar wind (flow of particles that streams from the Sun into the heliosphere) emerges, and how the system is restructured through the evolution of the solar surface flux. We will study how the coupling between corona and heliosphere depends on the solar cycle. Because of these goals, our proposal is ideally suited for the NSF Solar, Heliospheric, and Interplanetary Environment (SHINE). The solar corona and the inner heliosphere form a dynamically tied system. Thus far, we have represented them mostly as steady-state magnetohydrodynamic (MHD) solutions. However, a new paradigm is emerging, as time-dependent coronal models are becoming increasingly available. It is now imperative to consider whether the continuous magnetic flux evolution at the solar surface fundamentally changes the picture. In particular, the following questions remain unanswered: (1) Does the nature of open flux change between the two paradigms? (2) What is the origin of large-scale switchbacks and are they related to small-scale phenomena observed by PSP? (3) Are in situ measurements determined more by rotating through a structured heliosphere or by inherent variability along a given flux tube? (4) What are the implications for our current state-of-the-art empirical operational models of the inner heliosphere? These questions will be addressed by comparing ballistic mapping and steady-state models with a time-dependent coronal/heliospheric calculation. We will compute magnetic field mappings in both paradigms and quantify the statistical level of fluctuations. We also plan to construct another time-dependent model for the late declining phase (e.g., a Carrington rotation in 2017) to study how the solar cycle changes the evolution. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.