Observations of Solar Eruptions On-Disk through the Low Corona out to 4 solar radii: Current Observations from SDO and Proposed Instruments to Fill the Gap

Coronal Mass Ejections (CMEs) are among the most energetic phenomena in the solar system and a major source of space weather at the Earth and other planets, yet only a few serendipitous observations of the complete CME time profile have been constructed from the surface through the low and middle corona - the region where most of the CME acceleration occurs. The Extreme ultraviolet Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) is able to measure the CME speed on-disk during the very initial stages of the eruption, while the Atmospheric Imaging Assembly (AIA), also on SDO, is able to track the acceleration up to its outer edge of its field-of-view (FOV) around 1.5 solar radii.

To fill the gap and provide complete measurements of the CME acceleration profile, the Sun's Coronal Eruption Tracker (SunCET) was developed. This instrument package was proposed both as a 6U standalone CubeSat mission, called SunCET, and as a larger instrument package that will observe the Sun from L5, called SunCET-L5. These compact instruments are optimized to track the speed, acceleration, and mass of CMEs from the start of the eruption near the surface out to 4 solar radii. Each SunCET contains two types of instrument channels: The Dimming Irradiance Measurement Spectrometer (DIMS) and the Solar EUV Wide-Field Imager (SEWFI). DIMS use coronal dimming in EUV irradiance spectral lines at 0.1 nm resolution to determine the CME speed and mass on-disk. The CME is then imaged from on-disk out to 4 solar radii by the Solar EUV Wide-Field Imager (SEWFI) at 4.8ʺ/pixel. SunCET has a single DIMS channel with a spectral range from 17-34 nm and single SEWFI imaging channel in a broad 17-20 nm passband. SunCET-L5 has twice the channels, starting with the same aforementioned CubeSat channels with an additional DIMS spectrograph channel with spectral range from 6-18nm and an additional SEWFI imaging channel at 30.4nm. SunCET and SunCET-L5 will perform the first routine measurements of the CME acceleration profile from on-disk through the low corona and into the outer corona. The measurements will span the region of the solar source surface used in models of the coronal magnetic field and constrain models of CME initiation and acceleration.