Author： Sütterlin P. Wiehr E. Stellmacher G.
Publisher： Springer Publishing Company
ISSN： 0038-0938
Source： Solar Physics, Vol.189, Iss.1, 1999-10, pp. : 57-68
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Abstract
We have determined absolute continuum intensities and brightness temperatures of individual facular grains at a spatial resolution limited by the φ=50 cm aperture of the SVST on La Palma. A facular region at &thgr;≈57° was observed simultaneously in three narrow continuum windows at 450.5, 658.7, and 863.5 nm. We corrected for image degradation by the Earth's atmosphere using the speckle masking method. The brightness temperatures do not exactly follow the Planck law. The differences of T_blue-T_red=220 K and T_ir-T_red=-42 K reflect the wavelength dependence of the continuum formation depth. The (red) temperatures of 250 facular grains show excesses between 250 and 450 K above their undisturbed neighborhood. The wavelength dependence of the relative intensity ratios C_&lgr;=[I^fac/I^phot]_&lgr; show a large scatter around mean values of C_blue/C_red=1.075 and C_ir/C_red=0.98. We determined the center-to-limb variation of the 863.5 nm continuum contrast for 0.17
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