On extracting plasma compression signatures from white light coronal images

Abstract

We offer the intriguing possibility that the divergence of the plasma velocity (∇·V) in outward-moving density features can be extracted directly from coronal and heliospheric white-light images of coronal mass ejections (CMEs). The relevant empirical formula is quite simple to apply. It follows directly from the conservation of electrons. We derive an approximate relation between the measured white-light intensities in the brightest image pixels and the dominant electron densities along the pixel line of sight by invoking the generalized mean value theorem for integrals. If the formula holds with acceptable accuracy, we then may have a measure of not only (∇·V) itself, but also the related compressive acceleration rate of solar energetic particles within the CME.