A SOLAR SPICULE MODEL BASED UPON CALCIUM-II K LINE RADIATIVE TRANSFER STUDIES

Monte Carlo radiative transfer techniques are used to develop a height-dependent spicule model based upon a more realistic configuration than has hitherto been considered. The spicule is represented by a uniform cylinder, of finite length, standing vertically upon a plane chromosphere. The observed, limb-darkened, anisotropic chromospheric flux incident upon the cylinder is incorporated into the transfer calculations. The resulting model is characterized by a random, line broadening velocity of 20 km/sec, with electron temperature increasing from 6 × 103 K at the base to about 1.5 × 104 K at 11500 km above the solar surface. The corresponding values of electron density are 8 × 1011 cm-3 and 4 × 1010 cm-3. Contrast curves of the spicule model against the chromospheric background are computed and indicate that spicules should appear both bright and dark on the disk, depending upon their position with respect to the limb, the spectral frequency of observation and the viewing height. © 1969 D. Reidel Publishing Company.