2-DIMENSIONAL SPECTROSCOPY OF SUNSPOTS .1. INTENSITY, VELOCITY, AND VELOCITY POWER MAPS OF A SUNSPOT

A time series of two-dimensional spectra of a sunspot at theta approxi mate to 45 degrees has been obtained with a spectrometer based on a Fa bry-Perot interferometer. From our observations in the Fe I line at 70 9.04 nm we find that the gas plasma in the vicinity of the sunspot (th e moat) has a velocity of about 500 m/s directed outwards. Nevertheles s, the Evershed flow shows a sharp decrease by about 1000 m/s at the o uter boundary of the visible penumbra. The mean white-light image aver aged over 1(h)52(m) still shows radial structures in the penumbra, ind icating their long lifetime. Spatial variations of the velocities and continuum intensities have correlation coefficients of +0.66 for the c entre-side penumbra and -0.57 for the limb-side one. The correlation c oefficients increase to +/-0.75 for the line-centre intensities. This correlation confirms that the Evershed effect is related to the dark f ilaments. Outside the spot, the long-time average images of the contin uum and the line-centre intensities show a chain of bright dots with a size of about one arcsec and intensities up to 4.5% higher than their surroundings. These dots are related to the outer boundary of the vel ocity field in the moat. In the five-minute range, velocity power spec tra show a decrease in the umbra and in the penumbra, but no dependenc e on the radial structure. In the range between eight and twenty minut es, power is present in the centre-side penumbra; it resembles that of granular areas, but it has a radial structure. In the umbra or the li mb-side penumbra, the power values are much lower.