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Characteristics of Chromospheric Oscillation Periods in Magnetic Bright Points (MBPs)

In this investigation oscillation periods in Mg II k line intensity, brightness temperature, and Doppler velocity obtained above Magnetic Bright Points (MBPs) are investigated. For that purpose, data from the Interface Region Imaging Spectrometer (IRIS) observing the higher chromosphere and transition region (TR) were analysed together with imaging and magnetogram data obtained by Solar Dynamics Observatory (SDO). The MBPs were identified in combining Si IV 1403 A Slit Jaw Images (SJIs) with the magnetogram information from the Heliospheric and Magnetic Imager (HMI). A time-slice analysis followed by a wavelet inspection were carried out on the Mg II k (2796 A and 10,000 K) resonance lines for the detection of the oscillation period. Finally, a power spectrum analysis was performed to characterise the oscillations with the result that network points feature a typical intensity, temperature, and velocity oscillation period of about 300 seconds; The internetwork points have a mean intensity oscillation period of about 180 seconds, mean temperature oscillation period of about 202, and mean velocity oscillation period of about 202 seconds. In addition, one BP was analysed in detail, which demonstrates intensity oscillation periods with a value of 500 seconds, obviously not related to the common 3- or 5-minute oscillations found typically elsewhere in chromospheric/photospheric structures.