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

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 $\varphi (v,I)=\frac{\pi }{2}$, $\varphi (v,B_{los})=-\frac{\pi }{2}$. In addition, $\varphi (I,B_{los})=\pi$ 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 Alvènic 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.

20 pages, 12 figures

References in corpus (11)

• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Alfven Waves in the Lower Solar Atmosphere
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Optimization of the Spectral Line Inversion Code
• Channeling 5-min photospheric oscillations into the solar outer atmosphere through small-scale vertical magnetic flux tubes
• Surface-focused Seismic Holography of Sunspots: I. Observations
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Magnetohydrodynamics Simulation Module for the Global Solar Corona
• Hinode and IRIS observations of the magnetohydrodynamic waves propagating from the photosphere to the chromosphere in a sunspot
• Two-wave interaction in ideal magnetohydrodynamics
• Origin of the chromospheric three-minute oscillations in sunspot umbrae
• Numerical determination of the cutoff frequency in solar models
• Understanding the Fe I Line Measurements Returned by the Helioseismic and Magnetic Imager

Cited by in corpus (2)

• High-resolution wave dynamics in the lower solar atmosphere
• Exploring source region of 3-min slow magnetoacoustic waves observed in coronal fan loops rooted in sunspot umbra