Chapter 4

Oscillations in Ca II K₃ Observations of the Quiet-Sun Network

The spatial variation of chromospheric oscillations in network bright points (NBPs) is studied using high-resolution observations in Ca II K₃. Lightcurves, and hence power spectra, are created by isolating distinct regions of the NBP via a simple intensity thresholding technique. Using this technique, it is possible to identify peaks in the power spectra with particular spatial positions within each NBP. In particular, long-period oscillations (4-15 min; 1-4 mHz) were found in the central portions of each NBP, indicating that waves present are certainly not acoustic. These oscillations are possibly due to magneto-acoustic or magneto-gravity wave modes. We also show that spatially averaged or low spatial resolution power spectra can lead to an inability to detect such long-period waves.