About the directional properties of Solar Spicules from Hough Transform analysis

TL;DR

This study analyzes the directional properties of solar spicules using Hough Transform on high-resolution images, revealing how their orientation varies with solar latitude and magnetic field configurations.

Contribution

It introduces a novel statistical analysis of spicule orientations across different solar regions using Hough Transform on Hinode data.

Findings

Spicules are mostly radial in polar regions.

Tilt angles decrease in coronal holes with open magnetic fields.

Higher tilt angles are observed at lower latitudes.

Abstract

Spicules are intermittently rising above the surface of the Sun eruptions; EUV jets are now also reported in immediately above layers. The variation of spicule orientation with respect to the solar latitude, presumably reflecting the confinement and the focusing of ejecta by the surrounding global coronal magnetic field, is an important parameter to understand their dynamical properties. A wealth of high resolution images of limb spicules are made available in H CaII emission from the SOT Hinode mission. Furthermore, the Hough transform is applied to the resulting images for making a statistical analysis of spicule orientations in different regions around the solar limb, from the pole to the equator. Spicules are visible in a radial direction in the polar regions with a tilt angle (less than 200). The tilt angle is even reduced to 10 degrees inside the coronal hole with open magnetic field lines and at the lower latitude the tilt angle reaches values in excess of 50 degree.