New Data and Models of Running Penumbral Waves in Sunspots

We present new data on running penumbral waves (RPWs) obtained by appliction of special filtering techniques to high-resolution CCD images. We find for the first time that the waves decelerate from an initial velocity of 25 to around 10 km s-1 at the outer edge and are azimuthally symmetric. They are more or less circular and are only seen in symmetric, radial sectors of sunspot penumbrae. We did not see any outward decrease in amplitude. If present, it is not large. There appears to be a connection between umbral flashes and RPWs, but we cannot define it with the present data.

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