A geometrical model for polar plumes observed by STEREO SECCH

TL;DR

This paper presents a geometrical model for solar polar plumes observed by STEREO SECCHI, using polynomial functions to describe their expanding cross-sectional structure based on measured widths at various heights.

Contribution

It introduces a polynomial-based geometrical model to characterize the expansion of polar plumes, providing a new quantitative approach to their structure.

Findings

Derived polynomial parameters for 31 plumes at four heights

Quantified the cross-sectional expansion of polar plumes

Supported the expanding tube hypothesis for polar plume structure

Abstract

Solar polar plumes are bright radial rays rooted at the sun's polar areas. They are widely believed to have the structure of expanding tube. A four degree polynomial function was assumed to represent the change of cross section diameter as a function of height and four unknown parameters were calculated with measured average widths of total 31 plumes at 4 heights (1.04$R_s$,1.10$R_s$,1.16$R_s$,1.20$R_s$).