First Detection of Prominence Material Embedded within a 2 × 10⁶ K CME Front Streaming away at 100–1500 km s⁻¹ in the Solar Corona

Coronal mass ejections (CMEs) are the largest and most dynamic explosions detected in the million degree solar corona, with speeds reaching up to 3000 km s⁻¹ at Earth's orbit. Triggered by the eruption of prominences, in most cases, one of the outstanding questions pertaining to the dynamic CME-prominence system is the fate of the cool ${10}^4\text{--}{10}^{5}K$ ejected filaments. We present spectroscopic observations acquired during the 2015 March 20 total solar eclipse, which captured a plethora of redshifted plasmoids from Fe xiv emission at $2\times {10}^{6}K$. Approximately 10% of these plasmoids enshrouded the same neutral and singly ionized plasma below $2\times {10}^{5}K$, observed in prominences anchored at the Sun at that time. This discovery was enabled by the novel design of a dual-channel spectrometer and the exceptionally clear sky conditions on the island of Svalbard during totality. The Doppler redshifts corresponded to speeds ranging from under 100 to over 1500 km s⁻¹. These are the first comprehensive spectroscopic observations to unambiguously detect a $2\times {10}^{6}K$ filamentary CME front with inclusions of cool prominence material. The CME front covered a projected area of $2.5\times 1.5R_s^2$ starting from the solar surface. These observations imply that cool prominence inclusions within a CME front maintain their ionic composition during expansion away from the Sun.