Observation of the period ratio P_1/P_2 of transversal oscillations in solar macro-spicules

TL;DR

This study investigates the period ratios of transversal oscillations in solar macro-spicules using spectroscopic data, revealing deviations from expected values due to density stratification and magnetic twist.

Contribution

It provides the first detailed analysis of period ratios in macro-spicules using wavelet analysis of oxygen line profiles from SUMER/SOHO.

Findings

Period ratios deviate from the canonical value of 2.

Density stratification influences the period ratios.

Magnetic twist affects the observed oscillation periods.

Abstract

We analyze the time series of oxygen line profiles (O vi 1031.93 A and O vi 1037.61 A obtained from SUMER/SOHO on the solar south limb. We calculated Doppler shifts and consequently Doppler velocities in three heights 4", 14", and 24" from the limb on a coronal hole region. Then, we performed wavelet analysis with Morlet wavelet transform to determine the periods of fundamental mode and its first harmonic mode. The calculated period ratios have departures from its canonical value of $2$. The density stratification and magnetic twist are two main factors which may cause these departures.