Spectroscopic Studies of Limb Spicules. I Radial and Turbulent Velocities

Abstract

We made high-resolution spectroscopic observations of limb spicules in Hα using the Vertical Spectrograph of Domeless Solar Telescope at Hida Observatory. While more than half of the observed spicules have Gaussian line-profiles, some spicules have distinctly asymmetric profiles, which can be fitted to two Gaussian components. The faster component has radial velocities of 10-40 km s^-1 and Doppler widths of ∼0.4 Å, which suggest that it is from a single spicule oriented nearly along the line-of-sight. Profiles of the slower components and the single-Gaussian type show very similar characteristics. Their radial velocities are less than 10 km s^-1, and the Doppler widths are 0.6-0.9 Å. Nonthermal ``macroturbulent'' velocities on the order of 30 km s^-1 are required so as to explain these width values.