SHINE: Physics-based and Statistical Studies Connecting Surface-field Distributions to the Magnetic Flux Rope Structure in the Corona and Heliosphere

Coronal mass ejections (CMEs) from the Sun are the driver of extreme space weather near Earth. This project addresses the Solar, Heliospheric, and Interplanetary Environment (SHINE) goal of understanding the origin and evolution of CMEs through an investigation of magnetic flux ropes. The project is led by scientists from under-represented groups in STEM, who will mentor undergraduate students from underrepresented ethnic minority groups or first-generation college students.

The project advances the participation of women in science. Outreach will also be conducted in preparation for the October 2023 and April 2024 solar eclipses.

The central goal of this project is to obtain a quantitative understanding of the structure and evolution of magnetic flux ropes from the solar photosphere to the inner heliosphere. The scientific objective of the work is to determine how the reconnected magnetic flux in the solar source region drives the CME flux rope structure in the corona and heliosphere.

The proposed objective will be achieved by answering the questions: 1) Do flux ropes exist prior to eruptions, or are they formed during eruptions, or some combination of the two? 2) How magnetic reconnection affect the magnetic properties and kinematics of CME flux ropes? A combination of photospheric and coronal observations combined with flux rope fitting form the basis for geometrical and magnetic characterization of the “flux rope from eruption data” (FRED).

The team will determine the direction of the axial magnetic field and magnetic flux rope (MFR) helicity by a combination of magnetogram data and EUV eruptive features (e.g., coronal arcade skews, Fe XII stalks, sigmoids, and magnetic tongues) in solar source regions. Since the flux rope legs are anchored in the photosphere within the EUV core dimming regions in the eruption site, the magnetic flux within the core dimming region corresponds to the flux rope’s axial flux.

The reconnected flux within the post eruption arcade corresponds to the poloidal flux of the flux rope. Thus, a MFR is fully defined in the corona and its evolution is tracked under the assumption of self-similar expansion, enabling the prediction of the Bz (out of the ecliptic field) component that encounters Earth. The coronal flux rope structure will be compared against the flux rope in the heliosphere fitted to in-situ observations at various heliocentric distances (Parker Solar Probe, Solar Orbiter, and spacecraft near 1 AU), including self-similar expansion, helicity and the orientation of the coronal and interplanetary flux ropes.

The team will use the elliptical flux rope and graduated cylindrical shell techniques for forward modeling of the CME flux ropes. Both the Lepping cylindrical force-free magnetic cloud fitting and Marubashi cylinder and torus fitting are used to derive the MFR structure in CMEs.

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.