SUBMILLIMETER SOLAR LIMB PROFILES DETERMINED FROM OBSERVATIONS OF THE TOTAL SOLAR ECLIPSE OF 1988 MARCH 18

Observations were made of the extreme solar limb in six far-infrared wavelength bands ranging from 30 to 670-mu-m using the Kuiper Airborne Observatory during the total eclipse of the Sun on 1988 March 18. By observations of the occultation of the solar limb by the Moon, it was possible to obtain a spatial resolution of 0."5 normal to the limb. The results at wavelengths of 100-mu-m and less were found to be essentially equivalent to those obtained in 1986 by Lindsey et al., and we discuss here in detail only the results of the 200, 360, and 670-mu-m observations. The solar limb was found to be extended with respect to the visible limb at all of these wavelengths, with the extension increasing with wavelength. Limb brightening was observed to increase slightly with increasing wavelength, and no sign of a sharp emission spike at the extreme limb was found at any of these wavelengths. The observations can be well fitted by a chromospheric model incorporating cool dense spicules in the lower chromosphere.