6 research outputs found
Alfvenic waves in polar spicules
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.Comment: 8 pages, 10 figures, Accepted in Astronomy and Astrophysic