| Presentation Title: | CMEx: Chromospheric Magnetism Explorer |
| Author(s): | Holly Gilbert, Alfred de Wijn, Rebecca Centeno, Paul Bryans, Donald Schmit, Roberto Casini, Matthias Rempel, Giuliana de Toma, Daniela Lacatus, and the CMEx team |
Abstract:
CMEx is a SMEX mission selected for Phase-A concept study in NASA's Heliophysics program. CMEx uses ultraviolet spectropolarimetry to diagnose magnetism from the solar photosphere to the transition region, leveraging the heritage of the Hinode and IRIS missions, and the CLASP sounding rockets. CMEx explores how the magnetic field evolves from the high-β photosphere (i.e., plasma pressure greatly exceeds magnetic pressure) to the low-β magnetically-dominated corona to form twisted non-potential flux ropes that are the energy storage devices for magnetic eruptions. This key β transition happens in the chromosphere. Recent advances in the understanding of the polarization chromospheric lines in the near-UV, which are not observable from the ground, have primed a space-based mission like CMEx for success. CMEx observes many near-UV spectral lines, including the well-known Mg II h and k lines as well as a series of Fe II lines, with full-Stokes polarimetry to provide quantitative diagnostics of plasma parameters densely sampling the 9 pressure scale heights in the chromosphere, thus enabling studies of how the magnetic field in and around active regions gets reconfigured leading up to the eruption process, how flares lead to persistent changes in photospheric and chromospheric magnetic fields, and what the large-scale magnetic structure is of prominences in their stable phase, and how it changes in the transition from equilibrium to eruption. If selected for implementation, CMEx will fly in 2029, concurrently with SOLAR-C EUVST and MUSE, to largely fulfill the recommendations from the joint NASA/ESA/JAXA Next-Generation Solar Physics Mission report.