Transverse oscillations in chromospheric mottles

TL;DR

This study investigates transverse oscillations in chromospheric mottles on the solar disk, revealing their properties and interpreting them as magnetohydrodynamic kink waves, which enhances understanding of wave phenomena in the solar chromosphere.

Contribution

It provides the first detailed analysis of transverse oscillations in quiet Sun mottles and interprets these as MHD kink waves, expanding knowledge beyond limb features.

Findings

Over 40 transverse oscillations detected in mottles

Oscillation periods range from 70 to 280 seconds, most common at ~165 seconds

Oscillations are consistent with phase mixing and resonant mode conversion

Abstract

A number of recent investigations have revealed that transverse waves are ubiquitous in the solar chromosphere. The vast majority of these have been reported in limb spicules and active region fibrils. We investigate long-lived, quiet Sun, on-disk features such as chromospheric mottles (jet-like features located at the boundaries of supergranular cells) and their transverse motions. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument at the Dunn Solar Telescope. The dataset comprises simultaneous imaging in the H$\alpha$ core, Ca II K, and G band of an on-disk quiet Sun region. Time-distance techniques are used to study the characteristics of the transverse oscillations. We detect over 40 transverse oscillations in both bright and dark mottles, with periods ranging from 70 to 280 s, with the most frequent occurrence at ~ 165 s. The velocity amplitudes and transverse displacements exhibit characteristics similar to limb spicules. Neighbouring mottles oscillating in-phase are also observed. The transverse oscillations of individual mottles are interpreted in terms of magnetohydrodynamic kink waves. Their estimated periods and damping times are consistent with phase mixing and resonant mode conversion.