2021-05-03: 3-Part CME
The Mauna Loa K-Coronagraph (K-Cor) recorded a 3-part CME (loop-cavity-core) on the west limb of the Sun on May 3, 2021 from 20:52 to ~22:43 UT. At the beginning of the eruption two loops (likely part of an arcade) were visible, a brighter loop from position angle ~239 to 266 degrees, and a fainter loop that extended south to 225 degrees position angle. The loops overlapped as the event moved outward, appearing as one broad structure in the optically thin corona. The CME front was moving at approximately 550 km/sec with a final acceleration of ~80 m/s^2 as it left the K-Cor field-of-view (FOV) at ~3 solar radii and appeared to be moving slightly equatorward. The acceleration was decreasing as the event moved through the FOV. The core structure appears to disconnect, pinching down at its base to form an apparent wide “V” shape. A current sheet may be forming below the ‘V’ shape but is only visible for a short time. The ‘V’ shape and possible current sheet are best seen in subtractions. The overall width of the CME at 21:39:39 is ~120 degrees at 1.2 solar radii and is narrower, ~80 degrees, higher in the corona. The 80 degree width was measured at 1.65 solar radii.
The event may have originated slightly behind the west limb. An active region visible a day earlier had rotated over the west limb; no GOES X-ray event was recorded with this CME.