Alfvenic waves in polar spicules

TL;DR

This paper investigates the dynamic behavior of polar spicules using high-resolution Hinode/SOT observations, revealing helical motions, twisting, and untwisting phenomena that support a multi-component, surge-like interpretation of spicule dynamics.

Contribution

It provides new insights into the helical and twisting motions of polar spicules, supported by high-resolution space-based observations, enhancing understanding of their complex multi-component structure.

Findings

Spicules exhibit surge-like, untwisting multi-component behavior.

Presence of simultaneous left-handed and right-handed shearing motions.

Number of turns varies with spicule diameter, indicating twisting dynamics.

Abstract

Context. For investigating spicules from the photosphere to coronal heights, the new Hinode/SOT long series of high resolution observations from Space taken in CaII H line emission offers an improved way to look at their remarkable dynamical behavior using images free of seeing effects. They should be put in the context of the huge amount of already accumulated material from ground-based instruments, including high- resolution spectra of off-limb spicules. Results. The surge-like behavior of solar polar region spicules supports the untwisting multi-component interpretation of spicules exhibiting helical dynamics. Several tall spicules are found with (i) upward and downward flows similar at lower and middle-levels, the rate of upward motion being slightly higher at high levels; (ii) the left and right-hand velocities are also increasing with height; (iii) a large number of multi-component spicules show shearing motion of both left-handed and right-handed senses occurring simultaneously, which might be understood as twisting (or untwisting) threads. The number of turns depends on the overall diameter of the structure made of components and changes from at least one turn for the smallest structure to at most two or three turns for surge-like broad structures; the curvature along the spicule corresponds to a low turn number similar to a transverse kink mode oscillation along the threads.