Oscillations observed in Umbra, Plage, Quiet-Sun and the Polarity Inversion Line of Active Region 11158 using HMI/SDO Data

TL;DR

This study analyzes oscillations in various solar regions using HMI/SDO data, revealing wave modes, phase relations, and plasma motions that enhance understanding of solar magnetic activity and wave mechanics.

Contribution

It provides detailed phase and amplitude analysis of oscillations across different solar regions, identifying wave modes and plasma motions with high spatial and temporal resolution.

Findings

Detection of 5-minute oscillations with specific phase relations indicating wave modes.

Observation of Alfvénic waves along the polarity inversion line with propagation speeds of 2-6 km/s.

Identification of 3-minute waves in umbra regions, contributing to wave mode understanding.

Abstract

Using data from the Helioseismic Magnetic Imager, we report on the amplitudes and phase relations of oscillations in quiet-Sun, plage, umbra and the polarity inversion line (PIL) of an active region NOAA$\#$11158. We employ Fourier, wavelet and cross correlation spectra analysis. Waves with 5-minute periods are observed in umbra, PIL and plage with common phase values of ${\phi}(v,I)=\frac{\pi}{2}$, ${\phi}(v,B_{los})=-\frac{\pi}{2}$. In addition, ${\phi}(I,B_{los})=\pi$ in plage are observed. These phase values are consistent with slow standing or fast standing surface sausage wave modes. The line width variations, and their phase relations with intensity and magnetic oscillations, show different values within the plage and PIL regions, which may offer a way to further differentiate wave mode mechanics. Significant Doppler velocity oscillations are present along the PIL, meaning that plasma motion is perpendicular to the magnetic field lines, a signature of Alv\`enic waves. A time-distance diagram along a section of the PIL shows Eastward propagating Doppler oscillations converting into magnetic oscillations; the propagation speeds range between 2$-$6 km s$^{-1}$. Lastly, a 3-minute wave is observed in select regions of the umbra in the magnetogram data.