Observations of sunspot oscillations in G band and CaIIHline with Solar Optical Telescope on Hinode

Exploiting high-resolution observations made by the Solar Optical Telescope on board Hinode, we investigate the spatial distribution of the power spectral density of the oscillatory signal in and around the active region NOAA 10935. The G-band data show that in the umbra the oscillatory power is suppressed in all frequency ranges. On the other hand, in Ca II H intensity maps oscillations in the umbra, so-called umbral flashes, are clearly seen with the power peaking around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with the spatial scale of the umbral flashes over most of the umbra, but there is a region with suppressed power at the center of the umbra. The origin and property of this node-like feature remain unexplained.