Coronal Mass Ejections (CMEs): A novel method has been found to determine the instantaneous expansion speed and radial size of Coronal Mass Ejections (CMEs) from the Sun when it passes over a spacecraft at a single-point in the interplanetary medium.
o CME Expansion in Space: Expansion due to pressure differences with the solar wind affects their radial dimension, which has been inadequately studied.
o Existing Measurement Limitations: Previous single-point in situ methods are insufficient to estimate instantaneous expansion speed.
o Uses propagation speed of any two substructures to determine instantaneous expansion speed.
o Computes radial size and distance traveled by CME substructures at various points.
o CME’s aspect ratio first increases, remains constant, then decreases in interplanetary space.
o Helps in accurate prediction of CME arrival time and its effects on space weather.