The SunCET Mission: Unbroken 0-4 R☉ Observations for Tracking Full CME Acceleration Profiles

The Sun Coronal Ejection Tracker (SunCET) is a new CubeSat funded by NASA Heliophysics dedicated to figuring out how coronal mass ejections (CMEs) are accelerated. There are SO MANY theories and models about how stored up magnetic energy can be released to force massive amounts of plasma to escape its magnetic confinement. Perhaps the background magnetic field falls with height just steeply enough that even a small random expansion of a flux rope is enough to let it fly free (torus instability model). Or perhaps the boiling motion at the surface of the star twists the coronal magnetic field so much that the flux rope crosses a critical threshold (448°) and it’s suddenly kicked out (helical kink model). Magnetic energy release can continue to happen even after this initial phase, continuing to power the acceleration (e.g., varying velocity perturbations model). CMEs can also be deflected by the surrounding magnetic field they are passing through (e.g., ForeCAT model). All of these models produce unique predicted acceleration versus time profiles. The problem is we haven’t had the ideal observations to discriminate between them.

Enter SunCET, which solves the underlying technical hurdle that prevented prior observations from obtaining those complete acceleration profiles. The solar disk is 10 thousand to a billion times brighter than its surrounding corona, so prior observatories focused on only imaging one or the other, leaving a critical spatial gap between them… in exactly the place CMEs experience the bulk of their acceleration. SunCET observes the whole thing, from 0-4 solar radii with no gap. Our new simultaneous high dynamic range detector algorithm is SunCET’s enabling technology, which has broader applications for imaging and spectroscopy in astrophysics as well. The understanding we gain from SunCET CME observations and modeling efforts will inform our estimates of stellar CMEs and their impacts on the stellar environment. SunCET is expected to launch in early 2025.